| Revision as of 07:37, 13 October 2011 editChuispastonBot (talk | contribs)100,206 editsm r2.7.1) (Robot: Adding eo:Hipoklorita acido← Previous edit |
Latest revision as of 13:29, 13 December 2024 edit undoDMacks (talk | contribs)Edit filter managers, Autopatrolled, Administrators186,984 edits Removing from Category:Oxoacids using Cat-a-lot |
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| verifiedrevid = 445366114 |
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| ImageFile = Hypochlorous-acid-2D-dimensions.png |
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| ImageFile = Hypochlorous-acid-2D-dimensions.svg |
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| ImageSize = 150px |
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| ImageSize = 150px |
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| ImageName = hypochlorous acid bonding |
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| ImageName = hypochlorous acid bonding |
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| ImageFile1 = Hypochlorous-acid-3D-vdW.png |
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| ImageFile1 = Hypochlorous-acid-3D-vdW.svg |
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| ImageSize1 = 150px |
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| ImageSize1 = 150px |
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| ImageName1 = hypochlorous acid space filling |
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| ImageName1 = hypochlorous acid space filling |
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| ImageCaption1 = {{legend|white|], H}}{{legend|red|], O}}{{legend|lime|], Cl}} |
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| IUPACName = hypochlorous acid, chloric(I) acid, chloranol, hydroxidochlorine |
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| IUPACName = Hypochlorous acid |
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| OtherNames = Hydrogen hypochlorite, Chlorine hydroxide |
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| OtherNames = {{ubl|Chloranol|Chloric(I) acid|Chlorine hydroxide|Chlorooxidane|Hydrogen hypochlorite|Hypochloric acid|Hydroxidochlorine}} |
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| Section1 = {{Chembox Identifiers |
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|Section1={{Chembox Identifiers |
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| ChEBI_Ref = {{ebicite|correct|EBI}} |
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| ChEBI_Ref = {{ebicite|correct|EBI}} |
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| ChEBI = 24757 |
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| ChEBI = 24757 |
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| SMILES = ClO |
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| SMILES = OCl |
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| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}} |
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| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}} |
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| ChemSpiderID = 22757 |
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| ChemSpiderID = 22757 |
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| Section2 = {{Chembox Properties |
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|Section2={{Chembox Properties |
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| Formula = HClO |
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| Formula = HOCl |
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| H=1|O=1|Cl=1 |
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| MolarMass = 52.46 g/mol |
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| Appearance = Colorless aqueous solns |
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| Appearance = Colorless aqueous solution |
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| Density = Variable |
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| Density = Variable |
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| Solubility = Soluble |
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| Solubility = Soluble |
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| BoilingPt = |
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| BoilingPt = |
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| ConjugateBase = ] |
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| pKa = 7.53<ref>{{Cite document|last = Harris|first = Daniel C.|year = 2009|title = Exploring Chemical Analysis, Fourth Edition|page = 538}}</ref> |
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| pKa = 7.53<ref>{{Cite book |last = Harris|first = Daniel C.|year = 2009|title = Exploring Chemical Analysis |edition=Fourth |page = 538}}</ref> |
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| Section3 = {{Chembox Structure |
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| Section7 = {{Chembox Hazards |
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|Section7={{Chembox Hazards |
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| MainHazards = Oxidizer |
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| MainHazards = corrosive, oxidizing agent |
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| RPhrases = |
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| NFPA-H = 3 |
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| SPhrases = |
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| NFPA-F = 0 |
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| NFPA-R = 4 |
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| NFPA-S = OX |
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| HPhrases = {{H-phrases|320|335}} |
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| PPhrases = {{P-phrases|301+330+331|302+352|304+340|305+351+338}} |
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| Section8 = {{Chembox Related |
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| OtherAnions = {{ubl|]|]|]}} |
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| OtherCompounds = {{ubl|]|]|]|]|]|]|]|]|]|]|]|]|]}} |
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| OtherCpds = ]<br/>]<br/>] |
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'''Hypochlorous acid''' is an ] with the ] {{chem2|ClOH|auto=1}}, also written as HClO, HOCl, or ClHO.<ref>{{cite web|title=Hypochlorous acid|url=https://commonchemistry.cas.org/detail?cas_rn=7790-92-3|id=CAS RN: 7790-92-3|website=CAS Common Chemistry|publisher=], a division of the ], n.d.|access-date=2022-04-12}}</ref><ref>{{cite web|title=hypochlorous acid|url=https://www.ebi.ac.uk/chebi/searchId.do?chebiId=CHEBI:24757|id=CHEBI:24757|website=]|publisher=]|access-date=2022-04-12}}</ref> Its structure is {{chem2|H\sO\sCl}}. It is an ] that forms when ] dissolves in ], and itself partially ], forming a ] ], {{chem2|ClO−}}. HClO and {{chem2|ClO−}} are ]s, and the primary ] agents of chlorine solutions.<ref>Sansebastiano, G. et al. Page 262 in Food Safety: A Practical and Case Study Approach (Ed: R. J. Marshall) 2006, Springer Science & Business Media, Berlin.</ref> HClO cannot be isolated from these solutions due to rapid ] with its ], ]. |
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'''Hypochlorous acid''' is a weak ] with the ] HClO. It forms when ] dissolves in water. It cannot be isolated in pure form due to rapid equilibration with its precursor. HClO is an ], and as its sodium salt ], (NaClO), or its calcium salt ], (Ca(CIO)<sub><sub>2</sub></sub>) is used as a ], a ], and a ]. |
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Because of its strong antimicrobial properties, the related compounds ] (NaOCl) and ] ({{chem2|Ca(OCl)2}}) are ingredients in many commercial ], ]s, and ]s.<ref name=":2">{{Cite journal|last1=Block|first1=Michael S.|last2=Rowan|first2=Brian G.|date=September 2020|title=Hypochlorous Acid: A Review|journal=Journal of Oral and Maxillofacial Surgery|volume=78|issue=9|pages=1461–1466|doi=10.1016/j.joms.2020.06.029|issn=0278-2391|pmc=7315945|pmid=32653307}}</ref> The ]s of ]s, such as ]s, also contain hypochlorous acid as a tool against ].<ref name=":0">{{Cite web|title=Treating Chronic Wounds With Hypochlorous Acid Disrupts Biofilm|url=https://www.todayswoundclinic.com/articles/treating-chronic-wounds-hypochlorous-acid-disrupts-biofilm|access-date=2021-02-08|website=Today's Wound Clinic|language=en}}</ref> In living ]s, HOCl is generated by the reaction of ] with ] ] under the ] of the ] ] ] (MPO).<ref name="pmid27178483">{{cite journal | vauthors = Ghoshal K, et al | title = A novel sensor to estimate the prevalence of hypochlorous (HOCl) toxicity in individuals with type 2 diabetes and dyslipidemia | journal = Clinica Chimica Acta | volume = 458 | pages = 144–153 | date = July 2016 | pmid = 27178483 | doi = 10.1016/j.cca.2016.05.006 }}</ref> |
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==Uses== |
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In ], HCIO converts ]s to ]s.<ref>Unangst, P. C. "Hypochlorous Acid" in ''Encyclopedia of Reagents for Organic Synthesis'' (Ed: L. Paquette) 2004, J. Wiley & Sons, New York. {{doi|10.1002/047084289}}</ref> |
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Like many other disinfectants, hypochlorous acid solutions will destroy ], such as ], absorbed on surfaces.<ref>{{Cite web|last=US EPA|first=OCSPP|date=2020-03-13|title=List N: Disinfectants for Coronavirus (COVID-19)|url=https://www.epa.gov/pesticide-registration/list-n-disinfectants-coronavirus-covid-19|access-date=2021-02-08|website=US EPA|language=en}}</ref> In low concentrations, such solutions can serve to disinfect ]s.<ref name=":1">{{Cite web|date=2020-11-05|title=Pure Hypochlorous Acid: A Primer on pH and Wound Solutions|url=http://www.woundsource.com/blog/pure-hypochlorous-acid-primer-ph-and-wound-solutions|access-date=2021-02-08|website=WoundSource|language=en}}.</ref> <!--This does ''not'' imply that, as a previous version of this article stated, hypochlorous acid is non-toxic. First, as the saying goes, "the dose makes the poison"; many disinfectant solutions are extremely dilute. Second, a (possibly) infected open wound is sufficiently dangerous that an applying toxic substances thereto is an acceptable loss.--> |
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In ], hypochlorous acid is generated in activated ]s by myeloperoxidase-mediated peroxidation of chloride ions, and contributes to the destruction of ].<ref>{{cite journal|author = Harrison, J. E., and J. Schultz|year = 1976|title = Studies on the chlorinating activity of myeloperoxidase|journal = Journal of Biological Chemistry|volume = 251|issue = 5|pages = 1371–1374|pmid = 176150}}</ref><ref name=ref93>{{cite journal|author = Thomas, E. L.|year = 1979|title = Myeloperoxidase, hydrogen peroxide, chloride antimicrobial system: Nitrogen-chlorine derivatives of bacterial components in bactericidal action against ''Escherichia coli''|journal = Infect. Immun.|volume = 23|issue = 2|pages = 522–531|pmid = 217834|pmc = 414195}}</ref><ref name=ref3/> |
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== History == |
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In water treatment, hypochlorous acid is the active sanitizer{{Citation needed|date=July 2010}} in hypochlorite-based products (e.g. used in swimming pools). |
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Hypochlorous acid was discovered in 1834 by the French chemist ] (1802–1876) by adding, to a flask of chlorine gas, a dilute suspension of ] in water.<ref>See: |
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In food service and water distribution, specialized equipment to generate weak solutions of HOCl from water and salt is sometimes used to generate adequate quantities of safe (unstable) disinfectant to treat food preparation surfaces and water supplies.<ref>.</ref><ref> ''Hyatt's New Disinfectant/Cleaner Comes from the Tap'', ''Bloomberg Businessweek''.</ref> |
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* {{cite journal |last1=Balard |first1=A. J. |title=Recherches sur la nature des combinaisons décolorantes du chlore |journal=Annales de Chimie et de Physique |date=1834 |volume=57 |pages=225–304 |url=https://babel.hathitrust.org/cgi/pt?id=ien.35556014128060;view=1up;seq=230 |series=2nd series |trans-title=Investigations into the nature of bleaching compounds of chlorine |language=fr}} From p. 246: ''" … il est beaucoup plus commode … environ d'eau distillée."'' ( … it is much easier to pour, into flasks full of chlorine, red mercury oxide reduced to a fine powder by grinding and diluted in about twelve times its weight of distilled water.) |
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* {{cite book |last1=Graham |first1=Thomas |title=Elements of Chemistry |volume=4 |date=1840 |publisher=H. Baillière |location=London, England |page=367 |url=https://books.google.com/books?id=UF5QAAAAcAAJ&pg=PA367}}</ref> He also named the acid and its compounds.<ref>(Balard, 1834), p. 293. From p. 293: ''"Quelle dénomination … appelées ''hypochlorites''."'' (What name should one assign to this compound? It's obvious that that of "chlorous acid" can hardly be retained for it, and that it is more appropriate to call it ''hypochlorous'' acid, a name that recalls its similarity of composition with hyposulfurous acid, hypophosphorous acid, etc., formed, like it, from 1 equivalent of their radical and 1 equivalent of oxygen. Its compounds will be called ''hypochlorites''.)</ref> |
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Despite being relatively easy to make, it is difficult to maintain a stable hypochlorous acid solution. It is not until recent years that scientists have been able to cost-effectively produce and maintain hypochlorous acid water for stable commercial use. |
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==Formation, stablity and reactions== |
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Addition of ] to ] gives both hydrochloric acid (HCl) and hypochlorous acid:<ref name=ref2>{{cite journal|author = Fair, G. M., J. Corris, S. L. Chang, I. Weil, and R. P. Burden|year = 1948|title = The behavior of chlorine as a water disinfectant|journal = J. Am. Water Works Assoc.|volume = 40|pages = 1051–1061}}</ref> |
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==Uses== |
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:Cl<sub>2</sub> + H<sub>2</sub>O {{eqm}} HClO + HCl |
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* In ], HClO converts ]s to ]s.<ref>Unangst, P. C. "Hypochlorous Acid" in ''Encyclopedia of Reagents for Organic Synthesis'' (Ed: L. Paquette) 2004, J. Wiley & Sons, New York. {{doi|10.1002/047084289X.rh073}}</ref> |
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* In ], hypochlorous acid is generated in activated ]s by ]-mediated peroxidation of chloride ions, and contributes to the destruction of ].<ref>{{cite journal|author1=Harrison, J. E. |author2=J. Schultz|year = 1976|title = Studies on the chlorinating activity of myeloperoxidase|journal = Journal of Biological Chemistry|volume = 251|issue = 5|pages = 1371–1374|doi=10.1016/S0021-9258(17)33749-3|pmid = 176150|doi-access = free}}</ref><ref name=ref93>{{cite journal|author = Thomas, E. L.|year = 1979|title = Myeloperoxidase, hydrogen peroxide, chloride antimicrobial system: Nitrogen-chlorine derivatives of bacterial components in bactericidal action against ''Escherichia coli''|journal = Infect. Immun.|volume = 23|issue = 2|pages = 522–531|doi = 10.1128/IAI.23.2.522-531.1979|pmid = 217834|pmc = 414195}}</ref><ref name=ref3/> |
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*In medicine, hypochlorous acid water has been used as a disinfectant and sanitiser.<ref name=":0" /><ref name=":1" /><ref name=":2" /> |
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*In ],<ref>Wang L et al. "Hypochlorous acid as a potential wound care agent. Part I Stabilized hypochlorous acid: a component of the inorganic armamentarium of innate immunity". ''J Burns and Wounds'' 2007; April: 65–79.</ref><ref>Robson MC et al. . ''Journal of Burns and Wounds'' 2007; April: 80–90.</ref><ref>{{cite journal|last1=Selkon|first1=JB|display-authors=etal|year=2006|title=Evaluation of hypochlorous acid washes in the treatment of venous leg ulcers|journal=J Wound Care|volume=2006|issue=15|pages=33–37|doi=10.12968/jowc.2006.15.1.26861|pmid=16669304}}</ref> and as of early 2016 the U.S. Food and Drug Administration has approved products whose main active ingredient is hypochlorous acid for use in treating wounds and various infections in humans and pets. It is also FDA-approved as a preservative for saline solutions. |
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*In disinfection, it has been used in the form of liquid spray, wet wipes and aerosolised application. Recent studies have shown hypochlorous acid water to be suitable for fog and aerosolised application for disinfection chambers and suitable for disinfecting indoor settings such as offices, hospitals and healthcare clinics.<ref>{{Cite journal|last1=Nguyen|first1=Kate|last2=Bui|first2=Dinh|last3=Hashemi|first3=Mahak|last4=Hocking|first4=Dianna M|last5=Mendis|first5=Priyan|last6=Strugnell|first6=Richard A|last7=Dharmage|first7=Shyamali C|date=2021-01-22|title=The Potential Use of Hypochlorous Acid and a Smart Prefabricated Sanitising Chamber to Reduce Occupation-Related COVID-19 Exposure|journal=Risk Management and Healthcare Policy|volume=14|pages=247–252|doi=10.2147/RMHP.S284897|issn=1179-1594|pmc=7837568|pmid=33519249 |doi-access=free }}</ref> |
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* In food service and water distribution, specialized equipment to generate weak solutions of HClO from water and salt is sometimes used to generate adequate quantities of safe (unstable) disinfectant to treat food preparation surfaces and water supplies.<ref> {{Webarchive|url=https://web.archive.org/web/20190122201156/http://www.h2oxide.com/downloads/pdf/Disinfection%20of%20Facility%20H2O.pdf |date=2019-01-22 }}.</ref><ref>, ''Bloomberg Businessweek''.</ref> It is also commonly used in restaurants due to its non-flammable and nontoxic characteristics. |
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* In water treatment, hypochlorous acid is the active sanitizer in hypochlorite-based products (e.g. used in swimming pools).<ref>{{cite book |last1=Gonick |first1=Larry |last2=Criddle |first2=Craig |title=The cartoon guide to chemistry |chapter-url=https://archive.org/details/cartoonguidetoch00gonirich |chapter-url-access=registration |publisher=HarperResource |isbn=9780060936778 |page= |edition=1st |language=en |chapter=Chapter 9 Acid Basics |quote=Similarly, we add HOCl to swimming pools to kill bacteria.|date=2005-05-03 }}</ref> |
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* Similarly, in ships and yachts, marine sanitation devices<ref></ref> use electricity to convert seawater into hypochlorous acid to disinfect macerated faecal waste before discharge into the sea. |
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*In deodorization, hypochlorous acid has been tested to remove up to 99% of foul odours including garbage, rotten meat, toilet, stool, and urine odours.{{Citation needed|date=July 2022}} |
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==Formation, stability and reactions== |
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When acids are added to aqueous salts of hypochlorous acid (such as sodium hypochlorite in commercial bleach solution), the resultant reaction is driven to the left, and chlorine gas is evolved. Thus, the formation of stable hypochlorite bleaches is facilitated by dissolving chlorine gas into basic water solutions, such as ]. |
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Addition of ] to ] gives both ] (HCl) and hypochlorous acid (HClO):<ref name=ref2>{{cite journal|author = Fair, G. M., J. Corris, S. L. Chang, I. Weil, and R. P. Burden|year = 1948|title = The behavior of chlorine as a water disinfectant|journal = J. Am. Water Works Assoc.|volume = 40|issue = 10|pages = 1051–1061|doi = 10.1002/j.1551-8833.1948.tb15055.x|pmid = 18145494| bibcode=1948JAWWA..40j1051F }}</ref> |
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:{{chem2|Cl2 + H2O ⇌ HClO + HCl}} |
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The acid can also be prepared by dissolving ] in water; under standard aqueous conditions, anhydrous hypochlorous acid is impossible to prepare due to the readily reversible equilibrium between it and its anhydride<ref name="b2">''Inorganic chemistry'', Egon Wiberg, Nils Wiberg, Arnold Frederick Holleman , "Hypochlorous acid" p.442 , section 4.3.1</ref>: |
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:{{chem2|Cl2 + 4 OH− ⇌ 2 ClO− + 2 H2O + 2 e−}} |
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:{{chem2|Cl2 + 2 e− ⇌ 2 Cl−}} |
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When acids are added to aqueous salts of hypochlorous acid (such as sodium hypochlorite in commercial bleach solution), the resultant reaction is driven to the left, and chlorine gas is formed. Thus, the formation of stable hypochlorite bleaches is facilitated by dissolving chlorine gas into basic water solutions, such as ]. |
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:2 HOCl {{eqm}} Cl<sub>2</sub>O + H<sub>2</sub>O K(0°C) = 3.55{{e|-3}} dm<sup>3</sup>mol<sup>−1</sup> |
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The acid can also be prepared by dissolving ] in water; under standard aqueous conditions, anhydrous hypochlorous acid is currently impossible to prepare due to the readily reversible equilibrium between it and its anhydride:<ref name="b2" /> |
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The presence of light or transition metal oxides of copper, nickel, or cobalt accelerates the exothermic decomposition into ] and ]:<ref name="b2"/> |
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:{{chem2|2 HClO ⇌ Cl2O + H2O}}, ''K'' = 3.55 × 10<sup>−3</sup> dm<sup>3</sup>/mol (at 0 °C) |
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:2 Cl<sub>2</sub> + 2 H<sub>2</sub>O → 4 HCl + O<sub>2</sub> |
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The presence of light or transition metal oxides of ], ], or ] accelerates the exothermic{{dubious|date=September 2022}} decomposition into hydrochloric acid and ]:<ref name="b2" /> |
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===Chemical reactions=== |
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In ] solution, hypochlorous acid partially dissociates into the anion ''hypochlorite'' OCl<sup>−</sup>: |
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:{{chem2|2 Cl2 + 2 H2O → 4 HCl + O2}} |
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:HClO{{eqm}} OCl<sup>−</sup> + H<sup>+</sup> |
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===Fundamental reactions=== |
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]s of hypochlorous acid are called ]s. One of the best-known hypochlorites is ], the active ingredient in bleach. |
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In ] solution, hypochlorous acid partially dissociates into the anion ''hypochlorite'' {{chem2|ClO−}}: |
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:{{chem2|HClO ⇌ ClO− + H+}} |
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]s of hypochlorous acid are called ]s. One of the best-known hypochlorites is ], the active ingredient in bleach. |
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HClO is a stronger oxidant than chlorine under standard conditions. |
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HClO is a stronger oxidant than chlorine under standard conditions. |
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:{{hs|Cl}} 2{{hsp}}HClO(''aq'') + 2{{H+}} + 2{{e-}} {{eqm}} Cl<sub>2</sub>(''g'') + 2{{H2O}} E = +1.63 V |
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:{{chem2|2 HClO(aq) + 2 H+ + 2 e− ⇌ Cl2(g) + 2 H2O}}, ''E'' = +1.63 V |
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HClO reacts with HCl to form chlorine gas: |
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HClO reacts with HCl to form chlorine: |
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:{{chem2|HClO + HCl → H2O + Cl2}} |
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HClO reacts with ammonia to form ]: |
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:HClO + HCl → H<sub>2</sub>O + Cl<sub>2</sub> |
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:{{chem2|NH3 + HClO → NH2Cl + H2O}} |
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HClO can also react with organic ], forming ''N''-chloroamines. |
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Hypochlorous acid exists in equilibrium with its ], ].<ref name="b2">''Inorganic chemistry'', Egon Wiberg, Nils Wiberg, Arnold Frederick Holleman, "Hypochlorous acid", p. 442, section 4.3.1</ref> |
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:{{chem2|2 HClO ⇌ Cl2O + H2O}}, ''K'' = 3.55 × 10<sup>−3</sup> dm<sup>3</sup>/mol (at 0 °C) |
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===Reactivity of HClO with biomolecules=== |
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===Reactivity of HClO with biomolecules=== |
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Hypochlorous acid reacts with a wide variety of biomolecules including DNA, RNA,<ref name=ref3>{{cite journal|doi = 10.1073/pnas.78.1.210|author = Albrich, J. M., C. A. McCarthy, and J. K. Hurst|year = 1981|title = Biological reactivity of hypochlorous acid: Implications for microbicidal mechanisms of leukocyte myeloperoxidase|journal = Proc. Natl. Acad. Sci.|volume = 78|issue = 1|pages = 210–214|pmid = 6264434|pmc = 319021}}</ref><ref name=ref21>{{cite journal|doi = 10.1016/0043-1354(79)90023-X|author = Dennis, W. H., Jr, V. P. Olivieri, and C. W. Krusé|year = 1979|title = The reaction of nucleotides with aqueous hypochlorous acid|journal = Water Res|volume = 13|issue = 4|pages = 357–362}}</ref><ref name=ref45>Jacangelo, J. G., and V. P. Olivieri. 1984. Aspects of the mode of action of monochloramine. In R. L. Jolley, R. J. Bull, W. P. Davis, S. Katz, M. H. Roberts, Jr., and V. A. Jacobs (ed.), Water Chlorination, vol. 5. Lewis Publishers, Inc., Williamsburg.</ref><ref name=ref69>{{cite journal|last1=Prütz|first1=WA|title=Interactions of hypochlorous acid with pyrimidine nucleotides, and secondary reactions of chlorinated pyrimidines with GSH, NADH, and other substrates.|journal=Archives of biochemistry and biophysics|volume=349|issue=1|pages=183–91|year=1998|pmid=9439597|doi=10.1006/abbi.1997.0440}}</ref> fatty acid groups, cholesterol<ref name=ref7>{{cite journal|last1=Arnhold|first1=J|last2=Panasenko|first2=OM|last3=Schiller|first3=J|last4=Vladimirov|first4=YuA|last5=Arnold|first5=K|title=The action of hypochlorous acid on phosphatidylcholine liposomes in dependence on the content of double bonds. Stoichiometry and NMR analysis.|journal=Chemistry and physics of lipids|volume=78|issue=1|pages=55–64|year=1995|pmid=8521532|doi=10.1016/0009-3084(95)02484-Z}}</ref><ref name=ref16>{{cite journal|last1=Carr|first1=AC|last2=Van Den Berg|first2=JJ|last3=Winterbourn|first3=CC|title=Chlorination of cholesterol in cell membranes by hypochlorous acid|journal=Archives of biochemistry and biophysics|volume=332|issue=1|pages=63–9|year=1996|pmid=8806710|doi=10.1006/abbi.1996.0317}}</ref><ref name=ref23>{{cite journal|last1=Carr|first1=AC|last2=Vissers|first2=MC|last3=Domigan|first3=NM|last4=Winterbourn|first4=CC|title=Modification of red cell membrane lipids by hypochlorous acid and haemolysis by preformed lipid chlorohydrins|journal=Redox report : communications in free radical research|volume=3|issue=5–6|pages=263–71|year=1997|pmid=9754324}}</ref><ref name=ref37>{{cite journal|author=Hazell, L. J., J. V. D. Berg, and R. Stocker|year=1994|pmid=8068018|pmc=1137223|title= Oxidation of low density lipoprotein by hypochlorite causes aggregation that is mediated by modification of lysine residues rather than lipid oxidation|journal= Biochem. J.|pages= 297–304|volume=302}}</ref><ref name=ref39>{{cite journal|last1=Hazen|first1=SL|last2=Hsu|first2=FF|last3=Duffin|first3=K|last4=Heinecke|first4=JW|title=Molecular chlorine generated by the myeloperoxidase-hydrogen peroxide-chloride system of phagocytes converts low density lipoprotein cholesterol into a family of chlorinated sterols|journal=The Journal of biological chemistry|volume=271|issue=38|pages=23080–8|year=1996|pmid=8798498|doi=10.1074/jbc.271.38.23080}}</ref><ref name=ref97>{{cite journal|last1=Vissers|first1=MC|last2=Carr|first2=AC|last3=Chapman|first3=AL|title=Comparison of human red cell lysis by hypochlorous and hypobromous acids: insights into the mechanism of lysis|journal=The Biochemical journal|volume=330 ( Pt 1)|pages=131–8|year=1998|pmid=9461501|pmc=1219118}}</ref><ref name=ref98>{{cite journal|last1=Vissers|first1=MC|last2=Stern|first2=A|last3=Kuypers|first3=F|last4=Van Den Berg|first4=J|last5=Winterbourn|first5=CC|title=Membrane changes associated with lysis of red blood cells by hypochlorous acid|journal=Free radical biology & medicine|volume=16|issue=6|pages=703–12|year=1994|pmid=8070673|doi=10.1016/0891-5849(94)90185-6}}</ref><ref name=ref104>{{cite journal|last1=Winterbourn|first1=CC|last2=Van Den Berg|first2=JJ|last3=Roitman|first3=E|last4=Kuypers|first4=FA|title=Chlorohydrin formation from unsaturated fatty acids reacted with hypochlorous acid|journal=Archives of biochemistry and biophysics|volume=296|issue=2|pages=547–55|year=1992|pmid=1321589|doi=10.1016/0003-9861(92)90609-Z}}</ref> and proteins.<ref name=ref2>{{cite journal|last1=Albrich|first1=JM|last2=Hurst|first2=JK|title=Oxidative inactivation of Escherichia coli by hypochlorous acid. Rates and differentiation of respiratory from other reaction sites|journal=FEBS letters|volume=144|issue=1|pages=157–61|year=1982|pmid=6286355 | doi = 10.1016/0014-5793(82)80591-7 }}</ref><ref name=ref37/><ref name=ref9>{{cite journal|last1=Barrette Jr|first1=WC|last2=Hannum|first2=DM|last3=Wheeler|first3=WD|last4=Hurst|first4=JK|title=General mechanism for the bacterial toxicity of hypochlorous acid: abolition of ATP production|journal=Biochemistry|volume=28|issue=23|pages=9172–8|year=1989|pmid=2557918|doi=10.1021/bi00449a032}}</ref><ref name=ref46>{{cite journal|last1=Jacangelo|first1=J|last2=Olivieri|first2=V|last3=Kawata|first3=K|title=Oxidation of sulfhydryl groups by monochloramine|journal=Water Research|volume=21|pages=1339|year=1987|doi=10.1016/0043-1354(87)90007-8|issue=11}}</ref><ref name=ref48>{{cite journal|last1=Knox|first1=WE|last2=Stumpf|first2=PK|last3=Green|first3=DE|last4=Auerbach|first4=VH|title=The Inhibition of Sulfhydryl Enzymes as the Basis of the Bactericidal Action of Chlorine|journal=Journal of bacteriology|volume=55|issue=4|pages=451–8|year=1948|pmid=16561477|pmc=518466}}</ref><ref name=ref99>{{cite journal|last1=Vissers|first1=MC|last2=Winterbourn|first2=CC|title=Oxidative damage to fibronectin. I. The effects of the neutrophil myeloperoxidase system and HOCl|journal=Archives of biochemistry and biophysics|volume=285|issue=1|pages=53–9|year=1991|pmid=1846732|doi=10.1016/0003-9861(91)90327-F}}</ref><ref name=ref103>{{cite journal|last1=Winterbourn|first1=CC|title=Comparative reactivities of various biological compounds with myeloperoxidase-hydrogen peroxide-chloride, and similarity of the oxidant to hypochlorite|journal=Biochimica et biophysica acta|volume=840|issue=2|pages=204–10|year=1985|pmid=2986713}}</ref> |
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{{primary sources|date=January 2020}}Hypochlorous acid reacts with a wide variety of biomolecules, including ], ],<ref name=ref3>{{cite journal|doi = 10.1073/pnas.78.1.210|author = Albrich, J. M., C. A. McCarthy, and J. K. Hurst|year = 1981|title = Biological reactivity of hypochlorous acid: Implications for microbicidal mechanisms of leukocyte myeloperoxidase|journal = Proc. Natl. Acad. Sci.|volume = 78|issue = 1|pages = 210–214|pmid = 6264434|pmc = 319021|bibcode = 1981PNAS...78..210A|doi-access = free}}</ref><ref name=ref21>{{cite journal|doi = 10.1016/0043-1354(79)90023-X|author = Dennis, W. H., Jr, V. P. Olivieri, and C. W. Krusé|year = 1979|title = The reaction of nucleotides with aqueous hypochlorous acid|journal = Water Res|volume = 13|issue = 4|pages = 357–362| bibcode=1979WatRe..13..357D }}</ref><ref name=ref45>Jacangelo, J. G., and V. P. Olivieri. 1984. Aspects of the mode of action of monochloramine. In R. L. Jolley, R. J. Bull, W. P. Davis, S. Katz, M. H. Roberts, Jr., and V. A. Jacobs (ed.), Water Chlorination, vol. 5. Lewis Publishers, Inc., Williamsburg.</ref><ref name=ref69>{{cite journal|last1=Prütz|first1=WA|title=Interactions of hypochlorous acid with pyrimidine nucleotides, and secondary reactions of chlorinated pyrimidines with GSH, NADH, and other substrates.|journal=Archives of Biochemistry and Biophysics|volume=349|issue=1|pages=183–91|year=1998|pmid=9439597|doi=10.1006/abbi.1997.0440}}</ref> fatty acid groups, cholesterol<ref name=ref7>{{cite journal|last1=Arnhold|first1=J|last2=Panasenko|first2=OM|last3=Schiller|first3=J|last4=Vladimirov|first4=YuA|last5=Arnold|first5=K|title=The action of hypochlorous acid on phosphatidylcholine liposomes in dependence on the content of double bonds. Stoichiometry and NMR analysis|journal=Chemistry and Physics of Lipids|volume=78|issue=1|pages=55–64|year=1995|pmid=8521532|doi=10.1016/0009-3084(95)02484-Z}}</ref><ref name=ref16>{{cite journal|last1=Carr|first1=AC|last2=Van Den Berg|first2=JJ|last3=Winterbourn|first3=CC|title=Chlorination of cholesterol in cell membranes by hypochlorous acid|journal=Archives of Biochemistry and Biophysics|volume=332|issue=1|pages=63–9|year=1996|pmid=8806710|doi=10.1006/abbi.1996.0317}}</ref><ref name=ref23>{{cite journal|last1=Carr|first1=AC|last2=Vissers|first2=MC|last3=Domigan|first3=NM|last4=Winterbourn|first4=CC|title=Modification of red cell membrane lipids by hypochlorous acid and haemolysis by preformed lipid chlorohydrins|journal=Redox Report: Communications in Free Radical Research|volume=3|issue=5–6|pages=263–71|year=1997|pmid=9754324|doi=10.1080/13510002.1997.11747122|doi-access=free}}</ref><ref name=ref37>{{cite journal|author=Hazell, L. J., J. V. D. Berg, and R. Stocker|year=1994|pmid=8068018|pmc=1137223|title= Oxidation of low density lipoprotein by hypochlorite causes aggregation that is mediated by modification of lysine residues rather than lipid oxidation|journal= Biochem. J.|pages= 297–304|volume=302|issue=Pt 1 |doi=10.1042/bj3020297}}</ref><ref name=ref39>{{cite journal|last1=Hazen|first1=SL|last2=Hsu|first2=FF|last3=Duffin|first3=K|last4=Heinecke|first4=JW|title=Molecular chlorine generated by the myeloperoxidase-hydrogen peroxide-chloride system of phagocytes converts low density lipoprotein cholesterol into a family of chlorinated sterols|journal=The Journal of Biological Chemistry|volume=271|issue=38|pages=23080–8|year=1996|pmid=8798498|doi=10.1074/jbc.271.38.23080|doi-access=free}}</ref><ref name=ref97>{{cite journal|last1=Vissers|first1=MC|last2=Carr|first2=AC|last3=Chapman|first3=AL|title=Comparison of human red cell lysis by hypochlorous and hypobromous acids: insights into the mechanism of lysis|journal=The Biochemical Journal|volume=330|pages=131–8|year=1998|pmid=9461501|pmc=1219118|issue=1|doi=10.1042/bj3300131}}</ref><ref name=ref98>{{cite journal|last1=Vissers|first1=MC|last2=Stern|first2=A|last3=Kuypers|first3=F|last4=Van Den Berg|first4=J|last5=Winterbourn|first5=CC|title=Membrane changes associated with lysis of red blood cells by hypochlorous acid|journal=Free Radical Biology & Medicine|volume=16|issue=6|pages=703–12|year=1994|pmid=8070673|doi=10.1016/0891-5849(94)90185-6}}</ref><ref name=ref104>{{cite journal|last1=Winterbourn|first1=CC|last2=Van Den Berg|first2=JJ|last3=Roitman|first3=E|last4=Kuypers|first4=FA|title=Chlorohydrin formation from unsaturated fatty acids reacted with hypochlorous acid|journal=Archives of Biochemistry and Biophysics|volume=296|issue=2|pages=547–55|year=1992|pmid=1321589|doi=10.1016/0003-9861(92)90609-Z}}</ref> and proteins.<ref name=ref37/><ref name=albrich>{{cite journal|last1=Albrich|first1=JM|last2=Hurst|first2=JK|title=Oxidative inactivation of ''Escherichia coli'' by hypochlorous acid. Rates and differentiation of respiratory from other reaction sites|journal=FEBS Letters|volume=144|issue=1|pages=157–61|year=1982|pmid=6286355 | doi = 10.1016/0014-5793(82)80591-7 |s2cid=40223719|doi-access=free|bibcode=1982FEBSL.144..157A }}</ref><ref name=ref9>{{cite journal|last1=Barrette Jr|first1=WC|last2=Hannum|first2=DM|last3=Wheeler|first3=WD|last4=Hurst|first4=JK|title=General mechanism for the bacterial toxicity of hypochlorous acid: abolition of ATP production|journal=Biochemistry|volume=28|issue=23|pages=9172–8|year=1989|pmid=2557918|doi=10.1021/bi00449a032}}</ref><ref name=ref46>{{cite journal|last1=Jacangelo|first1=J|last2=Olivieri|first2=V|last3=Kawata|first3=K|title=Oxidation of sulfhydryl groups by monochloramine|journal=Water Research|volume=21|pages=1339–1344|year=1987|doi=10.1016/0043-1354(87)90007-8|issue=11|bibcode=1987WatRe..21.1339J}}</ref><ref name=ref48>{{cite journal|last1=Knox|first1=WE|last2=Stumpf|first2=PK|last3=Green|first3=DE|last4=Auerbach|first4=VH|title=The Inhibition of Sulfhydryl Enzymes as the Basis of the Bactericidal Action of Chlorine|journal=Journal of Bacteriology|volume=55|issue=4|pages=451–8|year=1948|doi=10.1128/JB.55.4.451-458.1948|pmid=16561477|pmc=518466}}</ref><ref name=ref99>{{cite journal|last1=Vissers|first1=MC|last2=Winterbourn|first2=CC|title=Oxidative damage to fibronectin. I. The effects of the neutrophil myeloperoxidase system and HOCl|journal=Archives of Biochemistry and Biophysics|volume=285|issue=1|pages=53–9|year=1991|pmid=1846732|doi=10.1016/0003-9861(91)90327-F}}</ref><ref name=ref103>{{cite journal|last1=Winterbourn|first1=CC|title=Comparative reactivities of various biological compounds with myeloperoxidase-hydrogen peroxide-chloride, and similarity of the oxidant to hypochlorite|journal=Biochimica et Biophysica Acta (BBA) - General Subjects|volume=840|issue=2|pages=204–10|year=1985|pmid=2986713|doi=10.1016/0304-4165(85)90120-5}}</ref> |
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====Reaction with protein sulfhydryl groups==== |
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====Reaction with protein sulfhydryl groups==== |
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Knox ''et al.''<ref name=ref48/> first noted that HClO is a ] inhibitor that, in sufficient quantity, could completely inactivate proteins containing ]. This is because HClO oxidises ], leading to the formation of ]s<ref name=ref67>{{cite journal|last1=Pereira|first1=WE|last2=Hoyano|first2=Y|last3=Summons|first3=RE|last4=Bacon|first4=VA|last5=Duffield|first5=AM|title=Chlorination studies. II. The reaction of aqueous hypochlorous acid with alpha-amino acids and dipeptides|journal=Biochimica et biophysica acta|volume=313|issue=1|pages=170–80|year=1973|pmid=4745674}}</ref> that can result in crosslinking of ]s. The HClO mechanism of ] oxidation is similar to that of ], and may only be bacteriostatic, because, once the residual chlorine is dissipated, some ] function can be restored.<ref name=ref46/> One ]-containing amino acid can scavenge up to four molecules of HOCl.<ref name=ref103/> Consistent with this, it has been proposed that ] of sulfur-containing ]s can be oxidized a total of three times by three HClO molecules, with the fourth reacting with the α-amino group. The first reaction yields ] (R-SOH) then ] (R-SO<sub>2</sub>H) and finally R-SO<sub>3</sub>H. Each of those intermediates can also condense with another ], causing cross-linking and aggregation of proteins. ] and R-SO<sub>3</sub>H derivatives are produced only at high molar excesses of HClO, and disulfides are formed primarily at bacteriocidal levels.<ref name=ref69/> Disulfide bonds can also be oxidized by HClO to sulfinic acid.<ref name=ref67/> Because the oxidation of ] and ] evolves ],<ref name=ref69/> this process results in the depletion HClO. |
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Knox ''et al.''<ref name=ref48/> first noted that HClO is a ] inhibitor that, in sufficient quantity, could completely inactivate proteins containing ]. This is because HClO oxidises sulfhydryl groups, leading to the formation of ]s<ref name=ref67>{{cite journal|last1=Pereira|first1=WE|last2=Hoyano|first2=Y|last3=Summons|first3=RE|last4=Bacon|first4=VA|last5=Duffield|first5=AM|title=Chlorination studies. II. The reaction of aqueous hypochlorous acid with alpha-amino acids and dipeptides|journal=Biochimica et Biophysica Acta|volume=313|issue=1|pages=170–80|year=1973|pmid=4745674|doi=10.1016/0304-4165(73)90198-0}}</ref> that can result in crosslinking of ]s. The HClO mechanism of sulfhydryl oxidation is similar to that of ], and may only be bacteriostatic, because once the residual chlorine is dissipated, some sulfhydryl function can be restored.<ref name=ref46/> One sulfhydryl-containing amino acid can scavenge up to four molecules of HClO.<ref name=ref103/> Consistent with this, it has been proposed that sulfhydryl groups of sulfur-containing ]s can be oxidized a total of three times by three HClO molecules, with the fourth reacting with the α-amino group. The first reaction yields ] ({{chem2|R\sS\sOH}}) then ] ({{chem2|R\sS(\dO)\sOH}}) and finally {{chem2|R\sS(\dO)2\sOH}}. Sulfenic acids form disulfides with another protein sulfhydryl group, causing cross-linking and aggregation of proteins. Sulfinic acid and {{chem2|R\sS(\dO)2\sOH}} derivatives are produced only at high molar excesses of HClO, and disulfides are formed primarily at bacteriocidal levels.<ref name=ref69/> Disulfide bonds can also be oxidized by HClO to sulfinic acid.<ref name=ref67/> Because the oxidation of sulfhydryls and ] evolves ],<ref name=ref69/> this process results in the depletion HClO. |
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====Reaction with protein amino groups==== |
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====Reaction with protein amino groups==== |
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Hypochlorous acid reacts readily with amino acids that have ] side-chains, with the chlorine from HClO displacing a hydrogen, resulting in an organic chloramine.<ref name=ref27>Dychdala, G. R. 1991. , pp. 131–151. In S. S. Block (ed.), Disinfection, Sterilization and Preservation. Lea & Febiger, Philadelphia. ISBN 0683307401</ref> Chlorinated ]s rapidly decompose, but ] chloramines are longer-lived and retain some oxidative capacity.<ref name=ref93/><ref name=ref103/> Thomas ''et al.''<ref name=ref93/> concluded from their results that most organic chloramines decayed by internal rearrangement and that fewer available ] groups promoted attack on the ], resulting in cleavage of the ]. McKenna and Davies<ref name=ref60>{{cite journal|last1=McKenna|first1=SM|last2=Davies|first2=KJ|title=The inhibition of bacterial growth by hypochlorous acid. Possible role in the bactericidal activity of phagocytes|journal=The Biochemical journal|volume=254|issue=3|pages=685–92|year=1988|pmid=2848494|pmc=1135139}}</ref> found that 10 mM or greater HClO is necessary to fragment proteins in vivo. Consistent with these results, it was later proposed that the chloramine undergoes a molecular rearrangement, releasing ] and ] to form an ].<ref name=ref38>{{cite journal|last1=Hazen|first1=SL|last2=D'avignon|first2=A|last3=Anderson|first3=MM|last4=Hsu|first4=FF|last5=Heinecke|first5=JW|title=Human neutrophils employ the myeloperoxidase-hydrogen peroxide-chloride system to oxidize alpha-amino acids to a family of reactive aldehydes. Mechanistic studies identifying labile intermediates along the reaction pathway|journal=The Journal of biological chemistry|volume=273|issue=9|pages=4997–5005|year=1998|pmid=9478947|doi=10.1074/jbc.273.9.4997}}</ref> The ] can further react with another ] to form a ], causing cross-linking and aggregation of proteins.<ref name=ref37/> |
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Hypochlorous acid reacts readily with amino acids that have ] side-chains, with the chlorine from HClO displacing a hydrogen, resulting in an organic chloramine.<ref name=ref27>Dychdala, G. R. 1991. , pp. 131–151. In S. S. Block (ed.), Disinfection, Sterilization and Preservation. Lea & Febiger, Philadelphia. {{ISBN|0-683-30740-1}}</ref> Chlorinated ]s rapidly decompose, but ] chloramines are longer-lived and retain some oxidative capacity.<ref name=ref93/><ref name=ref103/> Thomas ''et al.''<ref name=ref93/> concluded from their results that most organic chloramines decayed by internal rearrangement and that fewer available ] groups promoted attack on the ], resulting in cleavage of the ]. McKenna and Davies<ref name=ref60>{{cite journal|last1=McKenna|first1=SM|last2=Davies|first2=KJ|title=The inhibition of bacterial growth by hypochlorous acid. Possible role in the bactericidal activity of phagocytes|journal=The Biochemical Journal|volume=254|issue=3|pages=685–92|year=1988|pmid=2848494|pmc=1135139|doi=10.1042/bj2540685}}</ref> found that 10 mM or greater HClO is necessary to fragment proteins in vivo. Consistent with these results, it was later proposed that the chloramine undergoes a molecular rearrangement, releasing ] and ] to form an ].<ref name=ref38>{{cite journal|last1=Hazen|first1=SL|last2=D'Avignon|first2=A|last3=Anderson|first3=MM|last4=Hsu|first4=FF|last5=Heinecke|first5=JW|title=Human neutrophils employ the myeloperoxidase-hydrogen peroxide-chloride system to oxidize alpha-amino acids to a family of reactive aldehydes. Mechanistic studies identifying labile intermediates along the reaction pathway|journal=The Journal of Biological Chemistry|volume=273|issue=9|pages=4997–5005|year=1998|pmid=9478947|doi=10.1074/jbc.273.9.4997|doi-access=free}}</ref> The ] can further react with another ] to form a ], causing cross-linking and aggregation of proteins.<ref name=ref37/> |
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====Reaction with DNA and nucleotides==== |
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====Reaction with DNA and nucleotides==== |
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Hypochlourous acid reacts slowly with DNA and RNA as well as all nucleotides in vitro.<ref name=ref21/><ref name=ref68>{{cite journal|last1=Prütz|first1=WA|title=Hypochlorous acid interactions with thiols, nucleotides, DNA, and other biological substrates|journal=Archives of biochemistry and biophysics|volume=332|issue=1|pages=110–20|year=1996|pmid=8806715|doi=10.1006/abbi.1996.0322}}</ref> ] is the most reactive because HClO reacts with both the heterocyclic NH group and the amino group. In similar manner, ] with only a heterocyclic NH group that is reactive with HClO is the second-most reactive. ] and ], which have only a slowly reactive amino group, are less reactive with HClO.<ref name=ref68/> ] has been reported to be reactive only at a very slow rate.<ref name=ref3/><ref name=ref21/> The heterocyclic NH groups are more reactive than amino groups, and their secondary chloramines are able to donate the chlorine.<ref name=ref69/> These reactions likely interfere with DNA base pairing, and, consistent with this, Prütz<ref name=ref68/> has reported a decrease in viscosity of DNA exposed to HClO similar to that seen with heat denaturation. The sugar moieties are unreactive and the DNA backbone is not broken.<ref name=ref68/> NADH can react with chlorinated TMP and UMP as well as HClO. This reaction can regenerate UMP and TMP and results in the 5-hydroxy derivative of NADH. The reaction with TMP or UMP is slowly reversible to regenerate HClO. A second slower reaction that results in cleavage of the pyridine ring occurs when excess HClO is present. NAD+ is inert to HClO.<ref name=ref69/><ref name=ref68/> |
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Hypochlorous acid reacts slowly with DNA and RNA as well as all nucleotides in vitro.<ref name=ref21/><ref name=ref68>{{cite journal|last1=Prütz|first1=WA|title=Hypochlorous acid interactions with thiols, nucleotides, DNA, and other biological substrates|journal=Archives of Biochemistry and Biophysics|volume=332|issue=1|pages=110–20|year=1996|pmid=8806715|doi=10.1006/abbi.1996.0322}}</ref> ] is the most reactive because HClO reacts with both the heterocyclic NH group and the amino group. In similar manner, ] with only a heterocyclic NH group that is reactive with HClO is the second-most reactive. ] and ], which have only a slowly reactive amino group, are less reactive with HClO.<ref name=ref68/> ] has been reported to be reactive only at a very slow rate.<ref name=ref3/><ref name=ref21/> The heterocyclic NH groups are more reactive than amino groups, and their secondary chloramines are able to donate the chlorine.<ref name=ref69/> These reactions likely interfere with DNA base pairing, and, consistent with this, Prütz<ref name=ref68/> has reported a decrease in viscosity of DNA exposed to HClO similar to that seen with heat denaturation. The sugar moieties are nonreactive and the DNA backbone is not broken.<ref name=ref68/> NADH can react with chlorinated TMP and UMP as well as HClO. This reaction can regenerate UMP and TMP and results in the 5-hydroxy derivative of NADH. The reaction with TMP or UMP is slowly reversible to regenerate HClO. A second slower reaction that results in cleavage of the pyridine ring occurs when excess HClO is present. {{chem2|NAD+}} is inert to HClO.<ref name=ref69/><ref name=ref68/> |
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====Reaction with lipids==== |
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====Reaction with lipids==== |
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Hypochlorous acid reacts with ]s in ]s, but not ]s, and the ] ion does not participate in this reaction. This reaction occurs by ] with addition of ] to one of the carbons and a ] to the other. The resulting compound is a chlorhydrin.<ref name=ref7/> The polar ] disrupts ]s and could increase permeability.<ref name=ref16/> When chlorhydrin formation occurs in ]s of red blood cells, increased permeability occurs. Disruption could occur if enough chlorhydrin is formed.<ref name=ref7/><ref name=ref98/> The addition of preformed chlorhydrins to ]s can affect permeability as well.<ref name=ref23/> ] chlorhydrins have also been observed,<ref name=ref16/><ref name=ref39/> but do not greatly affect permeability, and it is believed that ] is responsible for this reaction.<ref name=ref39/> |
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Hypochlorous acid reacts with ]s in ]s, but not ]s, and the ] ion does not participate in this reaction. This reaction occurs by ] with addition of ] to one of the carbons and a ] to the other. The resulting compound is a chlorohydrin.<ref name=ref7/> The polar chlorine disrupts ]s and could increase permeability.<ref name=ref16/> When chlorohydrin formation occurs in lipid bilayers of red blood cells, increased permeability occurs. Disruption could occur if enough chlorohydrin is formed.<ref name=ref7/><ref name=ref98/> The addition of preformed chlorohydrin to red blood cells can affect permeability as well.<ref name=ref23/> ] chlorohydrin have also been observed,<ref name=ref16/><ref name=ref39/> but do not greatly affect permeability, and it is believed that ] is responsible for this reaction.<ref name=ref39/> Hypochlorous acid also reacts with a subclass of ]s called ]s, yielding chlorinated fatty ]s which are capable of protein modification and may play a role in inflammatory processes such as ] aggregation and the formation of ].<ref>{{cite journal |last1=Albert |first1=Carolyn J. |last2=Crowley |first2=Jan R. |last3=Hsu |first3=Fong-Fu |last4=Thukkani |first4=Arun K. |last5=Ford |first5=David A. |title=Reactive Chlorinating Species Produced by Myeloperoxidase Target the Vinyl Ether Bond of Plasmalogens |journal=Journal of Biological Chemistry |date=June 2001 |volume=276 |issue=26 |pages=23733–23741 |doi=10.1074/jbc.M101447200 |pmid=11301330 |doi-access=free }}</ref><ref>{{cite journal |last1=Yu |first1=Hong |last2=Wang |first2=Meifang |last3=Wang |first3=Derek |last4=Kalogeris |first4=Theodore J. |last5=McHowat |first5=Jane |last6=Ford |first6=David A. |last7=Korthuis |first7=Ronald J. |title=Chlorinated Lipids Elicit Inflammatory Responses in vitro and in vivo |journal=Shock |date=January 2019 |volume=51 |issue=1 |pages=114–122 |doi=10.1097/SHK.0000000000001112|pmid=29394241 |pmc=6070441 }}</ref><ref>{{cite journal |last1=Palladino |first1=ElisaN.D. |last2=Katunga |first2=Lalage A. |last3=Kolar |first3=Grant R. |last4=Ford |first4=David A. |title=2-Chlorofatty acids: lipid mediators of neutrophil extracellular trap formation |journal=Journal of Lipid Research |date=August 2018 |volume=59 |issue=8 |pages=1424–1432 |doi=10.1194/jlr.M084731 |doi-access=free |pmid=29739865 |pmc=6071778 }}</ref> |
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==Mode of disinfectant action== |
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==Mode of disinfectant action== |
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'']'' exposed to hypochlorous acid lose ] in less than 100 ms due to inactivation of many vital systems.<ref name="ref2"/><ref name=ref70>{{cite journal|last1=Rakita|first1=RM|last2=Michel|first2=BR|last3=Rosen|first3=H|title=Differential inactivation of Escherichia coli membrane dehydrogenases by a myeloperoxidase-mediated antimicrobial system|journal=Biochemistry|volume=29|issue=4|pages=1075–80|year=1990|pmid=1692736|doi=10.1021/bi00456a033}}</ref><ref name=ref71>{{cite journal|last1=Rakita|first1=RM|last2=Michel|first2=BR|last3=Rosen|first3=H|title=Myeloperoxidase-mediated inhibition of microbial respiration: damage to Escherichia coli ubiquinol oxidase|journal=Biochemistry|volume=28|issue=7|pages=3031–6|year=1989|pmid=2545243|doi=10.1021/bi00433a044}}</ref><ref name=ref76>{{cite journal|author=Rosen, H., and S. J. Klebanoff|year= 1985|title= Oxidation of microbial iron-sulfur centers by the myeloperoxidase-H2O2-halide antimicrobial system|journal= Infect. Immun.|volume= 47|issue=3|pages=613–618|pmid=2982737|pmc=261335}}</ref><ref name=ref79>{{cite journal|author=Rosen, H., R. M. Rakita, A. M. Waltersdorph, and S. J. Klebanoff|year= 1987|title= Myeloperoxidase-mediated damage to the succinate oxidase system of Escherichia coli|journal= J. Biol. Chem. |volume=242|pages=15004–15010}}</ref> Hypochlorous acid has a reported {{LD50}} of 0.0104–0.156 ppm<ref name=ref17>{{cite journal|last1=Chesney|first1=JA|last2=Eaton|first2=JW|last3=Mahoney Jr|first3=JR|title=Bacterial glutathione: a sacrificial defense against chlorine compounds|journal=Journal of bacteriology|volume=178|issue=7|pages=2131–5|year=1996|pmid=8606194|pmc=177915}}</ref> and 2.6 ppm caused 100% growth inhibition in 5 minutes.<ref name=ref60/> However it should be noted that the concentration required for bactericidal activity is also highly dependent on bacterial concentration.<ref name=ref48/> |
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'']'' exposed to hypochlorous acid ] in less than 0.1 seconds due to inactivation of many vital systems.<ref name="ref2"/><ref name=ref70>{{cite journal|last1=Rakita|first1=RM|last2=Michel|first2=BR|last3=Rosen|first3=H|title=Differential inactivation of ''Escherichia coli'' membrane dehydrogenases by a myeloperoxidase-mediated antimicrobial system|journal=Biochemistry|volume=29|issue=4|pages=1075–80|year=1990|pmid=1692736|doi=10.1021/bi00456a033}}</ref><ref name=ref71>{{cite journal|last1=Rakita|first1=RM|last2=Michel|first2=BR|last3=Rosen|first3=H|title=Myeloperoxidase-mediated inhibition of microbial respiration: damage to ''Escherichia coli'' ubiquinol oxidase|journal=Biochemistry|volume=28|issue=7|pages=3031–6|year=1989|pmid=2545243|doi=10.1021/bi00433a044}}</ref><ref name=ref76>{{cite journal|author1=Rosen, H. |author2=S. J. Klebanoff|year= 1985|title= Oxidation of microbial iron-sulfur centers by the myeloperoxidase-H2O2-halide antimicrobial system|journal= Infect. Immun.|volume= 47|issue=3|pages=613–618|doi=10.1128/IAI.47.3.613-618.1985|pmid=2982737|pmc=261335}}</ref><ref name=ref79>{{cite journal|author=Rosen, H., R. M. Rakita, A. M. Waltersdorph, and S. J. Klebanoff|year= 1987|title= Myeloperoxidase-mediated damage to the succinate oxidase system of ''Escherichia coli''|journal= J. Biol. Chem. |volume=242|pages=15004–15010|doi= 10.1016/S0021-9258(18)48129-X|doi-access= free}}</ref> Hypochlorous acid has a reported {{LD50}} of 0.0104–0.156 ppm<ref name=ref17>{{cite journal|last1=Chesney|first1=JA|last2=Eaton|first2=JW|last3=Mahoney Jr|first3=JR|title=Bacterial glutathione: a sacrificial defense against chlorine compounds|journal=Journal of Bacteriology|volume=178|issue=7|pages=2131–5|year=1996|pmid=8606194|pmc=177915|doi=10.1128/jb.178.7.2131-2135.1996}}</ref> and 2.6 ppm caused 100% growth inhibition in 5 minutes.<ref name=ref60/> However, the concentration required for bactericidal activity is also highly dependent on bacterial concentration.<ref name=ref48/> |
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===Inhibition of glucose oxidation=== |
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===Inhibition of glucose oxidation=== |
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In 1948, Knox ''et al.''<ref name=ref48/> proposed the idea that inhibition of ] oxidation is a major factor in the bacteriocidal nature of chlorine solutions. He proposed that the active agent or agents diffuse across the cytoplasmic membrane to inactivate key ]-containing ]s in the ]. This group was also the first to note that chlorine solutions (HOCl) inhibit ] ]s. Later studies have shown that, at bacteriocidal levels, the ] components do not react with HOCl.<ref name=ref1>{{Cite journal|last = Morris|first = J. C.|year = 1966|title = The acid ionization constant of HClO from 5 to 35 °|journal = ]|volume = 70|issue = 12|pages = 3798–3805|doi = 10.1021/j100884a007}}</ref> In agreement with this, McFeters and Camper<ref name=ref59>{{cite journal|last1=McFeters|first1=GA|last2=Camper|first2=AK|title=Enumeration of indicator bacteria exposed to chlorine|journal=Advances in applied microbiology|volume=29|pages=177–93|year=1983|pmid=6650262|doi=10.1016/S0065-2164(08)70357-5|chapter=Enumeration of Indicator Bacteria Exposed to Chlorine|series=Advances in Applied Microbiology|isbn=9780120026296}}</ref> found that ], an ] that Knox ''et al.''<ref name=ref48/> proposes would be inactivated, was unaffected by HOCl ]. It has been further shown that loss of ]s does not correlate with inactivation.<ref name=ref46/> That leaves the question concerning what causes inhibition of ] oxidation. The discovery that HOCl blocks induction of ] by added ]<ref name=ref8>{{cite journal|last1=Barrette Jr|first1=WC|last2=Albrich|first2=JM|last3=Hurst|first3=JK|title=Hypochlorous acid-promoted loss of metabolic energy in Escherichia coli|journal=Infection and immunity|volume=55|issue=10|pages=2518–25|year=1987|pmid=2820883|pmc=260739}}</ref> led to a possible answer to this question. The uptake of radiolabeled substrates by both ATP hydrolysis and proton ] may be blocked by exposure to HOCl preceding loss of viability.<ref name=ref1/> From this observation, it proposed that HOCl blocks uptake of nutrients by inactivating transport proteins.<ref name=ref9/><ref name=ref1/><ref name=ref59/><ref name=ref13>{{cite journal|last1=Camper|first1=AK|last2=McFeters|first2=GA|title=Chlorine injury and the enumeration of waterborne coliform bacteria|journal=Applied and environmental microbiology|volume=37|issue=3|pages=633–41|year=1979|pmid=378130|pmc=243267}}</ref> The question of loss of glucose oxidation has been further explored in terms of loss of respiration. Venkobachar ''et al.''<ref name=ref96>{{cite journal|last1=Venkobachar|first1=C|last2=Iyengar|first2=L|last3=Prabhakararao|first3=A|title=Mechanism of disinfection☆|journal=Water Research|volume=9|pages=119|year=1975|doi=10.1016/0043-1354(75)90160-8}}</ref> found that succinic dehydrogenase was inhibited in vitro by HOCl, which led to the investigation of the possibility that disruption of ] could be the cause of bacterial inactivation. Albrich ''et al.''<ref name=ref3/> subsequently found that HOCl destroys ]s and ]s and observed that oxygen uptake is abolished by HOCl and adenine nucleotides are lost. It was also observed that irreversible oxidation of ]s paralleled the loss of respiratory activity. One way of addressing the loss of oxygen uptake was by studying the effects of HOCl on succinate-dependent ].<ref name=ref43>{{cite journal|last1=Hurst|first1=JK|last2=Barrette Jr|first2=WC|last3=Michel|first3=BR|last4=Rosen|first4=H|title=Hypochlorous acid and myeloperoxidase-catalyzed oxidation of iron-sulfur clusters in bacterial respiratory dehydrogenases|journal=European journal of biochemistry / FEBS|volume=202|issue=3|pages=1275–82|year=1991|pmid=1662610|doi=10.1111/j.1432-1033.1991.tb16500.x}}</ref> Rosen ''et al.''<ref name=ref79/> found that levels of reductable ]s in HOCl-treated cells were normal, and these cells were unable to reduce them. Succinate dehydrogenase was also inhibited by HOCl, stopping the flow of electrons to oxygen. Later studies<ref name=ref71/> revealed that Ubiquinol oxidase activity ceases first, and the still-active ]s reduce the remaining quinone. The ]s then pass the ]s to ], which explains why the ]s cannot be reoxidized, as observed by Rosen ''et al.''<ref name=ref79/> However, this line of inquiry was ended when Albrich ''et al.''<ref name=ref2/> found that cellular inactivation precedes loss of respiration by using a flow mixing system that allowed evaluation of viability on much smaller time scales. This group found that cells capable of respiring could not divide after exposure to HOCl. |
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In 1948, Knox ''et al.''<ref name=ref48/> proposed the idea that inhibition of ] oxidation is a major factor in the bacteriocidal nature of chlorine solutions. They proposed that the active agent or agents diffuse across the cytoplasmic membrane to inactivate key ]-containing ]s in the ]. This group was also the first to note that chlorine solutions (HClO) inhibit ] ]s. Later studies have shown that, at bacteriocidal levels, the ] components do not react with HClO.<ref name=ref1>{{Cite journal|last = Morris|first = J. C.|year = 1966|title = The acid ionization constant of HClO from 5 to 35 °|journal = ]|volume = 70|issue = 12|pages = 3798–3805|doi = 10.1021/j100884a007}}</ref> In agreement with this, McFeters and Camper<ref name=ref59>{{cite book |last1=McFeters |first1=GA |last2=Camper |first2=AK |title=Enumeration of indicator bacteria exposed to chlorine |journal=Advances in Applied Microbiology |volume=29 |pages= |year=1983 |pmid=6650262 |doi=10.1016/S0065-2164(08)70357-5 |isbn=978-0-12-002629-6 |url=https://archive.org/details/advancesinapplie0029unse/page/177 }}</ref> found that ], an ] that Knox ''et al.''<ref name=ref48/> proposes would be inactivated, was unaffected by HClO ]. It has been further shown that loss of ]s does not correlate with inactivation.<ref name=ref46/> That leaves the question concerning what causes inhibition of ] oxidation. The discovery that HClO blocks induction of ] by added ]<ref name=ref8>{{cite journal|last1=Barrette Jr|first1=WC|last2=Albrich|first2=JM|last3=Hurst|first3=JK|title=Hypochlorous acid-promoted loss of metabolic energy in ''Escherichia coli''|journal=Infection and Immunity|volume=55|issue=10|pages=2518–25|year=1987|doi=10.1128/IAI.55.10.2518-2525.1987|pmid=2820883|pmc=260739}}</ref> led to a possible answer to this question. The uptake of radiolabeled substrates by both ATP hydrolysis and proton ] may be blocked by exposure to HClO preceding loss of viability.<ref name=ref1/> From this observation, it proposed that HClO blocks uptake of nutrients by inactivating transport proteins.<ref name=ref9/><ref name=ref1/><ref name=ref59/><ref name=ref13>{{cite journal|last1=Camper|first1=AK|last2=McFeters|first2=GA|title=Chlorine injury and the enumeration of waterborne coliform bacteria|journal=Applied and Environmental Microbiology|volume=37|issue=3|pages=633–41|year=1979|doi=10.1128/AEM.37.3.633-641.1979|pmid=378130|pmc=243267|bibcode=1979ApEnM..37..633C}}</ref> The question of loss of glucose oxidation has been further explored in terms of loss of respiration. Venkobachar ''et al.''<ref name=ref96>{{cite journal|last1=Venkobachar|first1=C|last2=Iyengar|first2=L|last3=Prabhakararao|first3=A|title=Mechanism of disinfection☆|journal=Water Research|volume=9|pages=119–124|year=1975|issue=1|doi=10.1016/0043-1354(75)90160-8|bibcode=1975WatRe...9..119V}}</ref> found that succinic dehydrogenase was inhibited in vitro by HClO, which led to the investigation of the possibility that disruption of ] could be the cause of bacterial inactivation. Albrich ''et al.''<ref name=ref3/> subsequently found that HClO destroys ]s and ]s and observed that oxygen uptake is abolished by HClO and adenine nucleotides are lost. It was also observed that irreversible oxidation of ]s paralleled the loss of respiratory activity. One way of addressing the loss of oxygen uptake was by studying the effects of HClO on succinate-dependent ].<ref name=ref43>{{cite journal|last1=Hurst|first1=JK|last2=Barrette Jr|first2=WC|last3=Michel|first3=BR|last4=Rosen|first4=H|title=Hypochlorous acid and myeloperoxidase-catalyzed oxidation of iron-sulfur clusters in bacterial respiratory dehydrogenases|journal=European Journal of Biochemistry|volume=202|issue=3|pages=1275–82|year=1991|pmid=1662610|doi=10.1111/j.1432-1033.1991.tb16500.x|doi-access=free}}</ref> Rosen ''et al.''<ref name=ref79/> found that levels of reductable ]s in HClO-treated cells were normal, and these cells were unable to reduce them. Succinate dehydrogenase was also inhibited by HClO, stopping the flow of electrons to oxygen. Later studies<ref name=ref71/> revealed that Ubiquinol oxidase activity ceases first, and the still-active ]s reduce the remaining quinone. The ]s then pass the ]s to ], which explains why the ]s cannot be reoxidized, as observed by Rosen ''et al.''<ref name=ref79/> However, this line of inquiry was ended when Albrich ''et al.''<ref name=albrich/> found that cellular inactivation precedes loss of respiration by using a flow mixing system that allowed evaluation of viability on much smaller time scales. This group found that cells capable of respiring could not divide after exposure to HClO. |
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===Depletion of adenine nucleotides=== |
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===Depletion of adenine nucleotides=== |
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Having eliminated loss of respiration Albrich ''et al.''<ref name=ref2/> proposes that the cause of death may be due to metabolic dysfunction caused by depletion of adenine nucleotides. Barrette ''et al.''<ref name=ref8/> studied the loss of adenine nucleotides by studying the energy charge of HOCl-exposed cells and found that cells exposed to HOCl were unable to step up their energy charge after addition of nutrients. The conclusion was that exposed cells have lost the ability to regulate their adenylate pool, based on the fact that metabolite uptake was only 45% deficient after exposure to HOCl and the observation that HOCl causes intracellular ATP hydrolysis. It was also confirmed that, at bacteriocidal levels of HOCl, cytosolic components are unaffected. So it was proposed that modification of some membrane-bound protein results in extensive ATP hydrolysis, and this, coupled with the cells inability to remove AMP from the cytosol, depresses metabolic function. One protein involved in loss of ability to regenerate ATP has been found to be ].<ref name=ref9/> Much of this research on respiration reconfirms the observation that relevant bacteriocidal reactions take place at the cell membrane.<ref name=ref9/><ref name=ref8/><ref name=ref75>{{cite journal|last1=Rosen|first1=H|last2=Klebanoff|first2=SJ|title=Oxidation of Escherichia coli iron centers by the myeloperoxidase-mediated microbicidal system|journal=The Journal of biological chemistry|volume=257|issue=22|pages=13731–35|year=1982|pmid=6292201}}</ref> |
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Having eliminated loss of respiration, Albrich ''et al.''<ref name=albrich/> proposes that the cause of death may be due to metabolic dysfunction caused by depletion of adenine nucleotides. Barrette ''et al.''<ref name=ref8/> studied the loss of adenine nucleotides by studying the energy charge of HClO-exposed cells and found that cells exposed to HClO were unable to step up their energy charge after addition of nutrients. The conclusion was that exposed cells have lost the ability to regulate their adenylate pool, based on the fact that metabolite uptake was only 45% deficient after exposure to HClO and the observation that HClO causes intracellular ATP hydrolysis. It was also confirmed that, at bacteriocidal levels of HClO, cytosolic components are unaffected. So it was proposed that modification of some membrane-bound protein results in extensive ATP hydrolysis, and this, coupled with the cells inability to remove AMP from the cytosol, depresses metabolic function. One protein involved in loss of ability to regenerate ATP has been found to be ].<ref name=ref9/> Much of this research on respiration reconfirms the observation that relevant bacteriocidal reactions take place at the cell membrane.<ref name=ref9/><ref name=ref8/><ref name=ref75>{{cite journal|last1=Rosen|first1=H|last2=Klebanoff|first2=SJ|title=Oxidation of ''Escherichia coli'' iron centers by the myeloperoxidase-mediated microbicidal system|journal=The Journal of Biological Chemistry|volume=257|issue=22|pages=13731–35|year=1982|doi=10.1016/S0021-9258(18)33509-9|pmid=6292201|doi-access=free}}</ref> |
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===Inhibition of DNA replication=== |
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===Inhibition of DNA replication=== |
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Recently it has been proposed that bacterial inactivation by HOCl is the result of inhibition of ] replication. When bacteria are exposed to HOCl, there is a precipitous decline in ] that precedes inhibition of ] synthesis, and closely parallels loss of viability.<ref name=ref60/><ref name=ref78>{{cite journal|last1=Rosen|first1=H|last2=Orman|first2=J|last3=Rakita|first3=RM|last4=Michel|first4=BR|last5=Vandevanter|first5=DR|title=Loss of DNA-membrane interactions and cessation of DNA synthesis in myeloperoxidase-treated Escherichia coli|journal=Proceedings of the National Academy of Sciences of the United States of America|volume=87|issue=24|pages=10048–52|year=1990|pmid=2175901|pmc=55312|doi=10.1073/pnas.87.24.10048}}</ref> During bacterial genome replication, the ] (oriC in ''E. coli'') binds to proteins that are associated with the cell membrane, and it was observed that HOCl treatment decreases the affinity of extracted membranes for oriC, and this decreased affinity also parallels loss of viability. A study by Rosen ''et al.''<ref name=ref77>{{cite journal|last1=Rosen|first1=H|last2=Michel|first2=BR|last3=Vandevanter|first3=DR|last4=Hughes|first4=JP|title=Differential effects of myeloperoxidase-derived oxidants on Escherichia coli DNA replication|journal=Infection and immunity|volume=66|issue=6|pages=2655–9|year=1998|pmid=9596730|pmc=108252}}</ref> compared the rate of HOCl inhibition of DNA replication of plasmids with different replication origins and found that certain plasmids exhibited a delay in the inhibition of replication when compared to plasmids containing oriC. Rosen’s group proposed that inactivation of membrane proteins involved in DNA replication are the mechanism of action of HOCl. |
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Recently it has been proposed that bacterial inactivation by HClO is the result of inhibition of ] replication. When bacteria are exposed to HClO, there is a precipitous decline in ] that precedes inhibition of ] synthesis, and closely parallels loss of viability.<ref name=ref60/><ref name=ref78>{{cite journal|last1=Rosen|first1=H|last2=Orman|first2=J|last3=Rakita|first3=RM|last4=Michel|first4=BR|last5=Vandevanter|first5=DR|title=Loss of DNA-membrane interactions and cessation of DNA synthesis in myeloperoxidase-treated ''Escherichia coli''|journal=Proceedings of the National Academy of Sciences of the United States of America|volume=87|issue=24|pages=10048–52|year=1990|pmid=2175901|pmc=55312|doi=10.1073/pnas.87.24.10048|bibcode=1990PNAS...8710048R|doi-access=free}}</ref> During bacterial genome replication, the ] (oriC in ''E. coli'') binds to proteins that are associated with the cell membrane, and it was observed that HClO treatment decreases the affinity of extracted membranes for oriC, and this decreased affinity also parallels loss of viability. A study by Rosen ''et al.''<ref name=ref77>{{cite journal|last1=Rosen|first1=H|last2=Michel|first2=BR|last3=Vandevanter|first3=DR|last4=Hughes|first4=JP|title=Differential effects of myeloperoxidase-derived oxidants on ''Escherichia coli'' DNA replication|journal=Infection and Immunity|volume=66|issue=6|pages=2655–9|year=1998|doi=10.1128/IAI.66.6.2655-2659.1998|pmid=9596730|pmc=108252}}</ref> compared the rate of HClO inhibition of DNA replication of plasmids with different replication origins and found that certain plasmids exhibited a delay in the inhibition of replication when compared to plasmids containing oriC. Rosen's group proposed that inactivation of membrane proteins involved in DNA replication are the mechanism of action of HClO. |
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===Protein unfolding and aggregation=== |
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===Protein unfolding and aggregation=== |
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HOCl is known to cause post-translational modifications to ], the notable ones being ] and ] oxidation. A recent examination of HOCl's bactericidal role revealed it to be a potent inducer of protein aggregation.<ref>{{cite journal|last1=Winter|first1=J.|last2=Ilbert|first2=M.|last3=Graf|first3=P.C.F.|last4=Özcelik|first4=D.|last5=Jakob|first5=U.|title=Bleach Activates a Redox-Regulated Chaperone by Oxidative Protein Unfolding|journal=Cell|volume=135|issue=4|pages=691|year=2008|pmid=19013278|pmc=2606091|doi=10.1016/j.cell.2008.09.024}}</ref> Hsp33, a chaperone known to be activated by oxidative heat stress, protects bacteria from the effects of HOCl by acting as a holdase, effectively preventing protein aggregation. Strains of E. coli and Vibrio cholerae lacking Hsp33 were rendered especially sensitive to HOCl. Hsp33 protected many essential proteins from aggregation and inactivation due to HOCl, which is a probable mediator of HOCl's bactericidal effects. |
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HClO is known to cause post-translational modifications to ], the notable ones being ] and ] oxidation. A recent examination of HClO's bactericidal role revealed it to be a potent inducer of protein aggregation.<ref>{{cite journal|last1=Winter|first1=J.|last2=Ilbert|first2=M.|last3=Graf|first3=P.C.F.|last4=Özcelik|first4=D.|last5=Jakob|first5=U.|title=Bleach Activates a Redox-Regulated Chaperone by Oxidative Protein Unfolding|journal=Cell|volume=135|issue=4|pages=691–701|year=2008|pmid=19013278|pmc=2606091|doi=10.1016/j.cell.2008.09.024}}</ref> Hsp33, a chaperone known to be activated by oxidative heat stress, protects bacteria from the effects of HClO by acting as a ], effectively preventing protein aggregation. Strains of '']'' and '']'' lacking Hsp33 were rendered especially sensitive to HClO. Hsp33 protected many essential proteins from aggregation and inactivation due to HClO, which is a probable mediator of HClO's bactericidal effects. |
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==Hypochlorites== |
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==Hypochlorites== |
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===Production of hypochlorites using electrolysis=== |
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===Production of hypochlorites using electrolysis=== |
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{{See also|Chloralkali process}} |
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{{See also|Chloralkali process}} |
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Solutions of hypochlorites can be produced by electrolysis of an aqueous chloride solution. Chlorine gas is produced at the anode, while hydrogen forms at the cathode. Some of the chlorine gas produced will dissolve forming hypochlorite ions. Hypochlorites are also produced by the ] of chlorine gas in alkaline solutions. |
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Solutions of hypochlorites can be produced in-situ by electrolysis of an aqueous sodium chloride solution in both batch and flow processes.<ref>{{Cite journal|last1=Migliarina|first1=Franco|last2=Ferro|first2=Sergio|date=December 2014|title=A Modern Approach to Disinfection, as Old as the Evolution of Vertebrates|journal=Healthcare|language=en|volume=2|issue=4|pages=516–526|doi=10.3390/healthcare2040516|pmc=4934573|pmid=27429291|doi-access=free}}</ref> The composition of the resulting solution depends on the pH at the anode. In acid conditions the solution produced will have a high hypochlorous acid concentration, but will also contain dissolved gaseous chlorine, which can be corrosive, at a neutral pH the solution will be around 75% hypochlorous acid and 25% hypochlorite. Some of the chlorine gas produced will dissolve forming hypochlorite ions. Hypochlorites are also produced by the ] of chlorine gas in alkaline solutions. |
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==Safety== |
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==Safety== |
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HClO is classified as non-hazardous by the ] in the US. As an oxidising agent, it can be corrosive or irritant depending on its concentration and pH. |
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HOCl is a strong oxidizer and can form explosive mixtures. |
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In a clinical test, hypochlorous acid water was tested for eye irritation, skin irritation, and toxicity. The test concluded that it was non-toxic and non-irritating to the eye and skin.<ref>{{Cite journal|last1=Wang|first1=L|last2=Bassiri|first2=M|last3=Najafi|first3=R|last4=Najafi|first4=K|last5=Yang|first5=J|last6=Khosrovi|first6=B|last7=Hwong|first7=W|last8=Barati|first8=E|last9=Belisle|first9=B|last10=Celeri|first10=C|last11=Robson|first11=MC|date=2007-04-11|title=Hypochlorous Acid as a Potential Wound Care Agent|journal=Journal of Burns and Wounds|volume=6|pages=e5|issn=1554-0766|pmc=1853323|pmid=17492050}}</ref> |
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In a 2017 study, a saline hygiene solution preserved with pure hypochlorous acid was shown to reduce the bacterial load significantly without altering the diversity of bacterial species on the eyelids. After 20 minutes of treatment, there was more than 99% reduction of the ''Staphylococci'' bacteria.<ref>{{Cite journal|last1=Stroman|first1=D. W|last2=Mintun|first2=K|last3=Epstein|first3=A. B|last4=Brimer|first4=C. M|last5=Patel|first5=C. R|last6=Branch|first6=J. D|last7=Najafi-Tagol|first7=K|year=2017|title=Reduction in bacterial load using hypochlorous acid hygiene solution on ocular skin|journal=Clinical Ophthalmology|volume=11|pages=707–714|doi=10.2147/OPTH.S132851|pmc=5402722|pmid=28458509 |doi-access=free }}</ref> |
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==Commercialisation== |
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Commercial disinfection applications remained elusive for a long time after the discovery of hypochlorous acid because the stability of its solution in water is difficult to maintain. The active compounds quickly deteriorate back into salt water, losing the solution its disinfecting capability, which makes it difficult to transport for wide use. It is less commonly used as a disinfectant compared to bleach and alcohol due to cost, despite its stronger disinfecting capabilities. |
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Technological developments have reduced manufacturing costs and allow for manufacturing and bottling of hypochlorous acid water for home and commercial use. However, most hypochlorous acid water has a short shelf life. Storing away from heat and direct sunlight can help slow the deterioration. The further development of continuous flow electrochemical cells has been implemented in new products, allowing the commercialisation of domestic and industrial continuous flow devices for the in-situ generation of hypochlorous acid for disinfection purposes.<ref>{{Cite web|title=In situ generation: Active substances vs biocidal products|url=https://www.hse.gov.uk/biocides/in-situ-generation.htm|access-date=2021-07-12|website=www.hse.gov.uk}}</ref> |
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==See also== |
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==References== |
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* : a summary of the municipal tapwater treatment process |
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{{Hydrogen compounds}} |
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{{Hydrogen compounds}} |
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{{Hypochlorites}} |
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{{Authority control}} |
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