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The enzyme xanthan lyase (EC 4.2.2.12) catalyzes the following process:

Eliminative cleavage of the terminal β-D-mannosyl-(1→4)-β-D-glucuronosyl linkage of the side-chain of the polysaccharide xanthan, leaving a 4-deoxy-α-L-threo-hex-4-enuronosyl group at the terminus of the side-chain

It belongs to the family of lyases, specifically those carbon-oxygen lyases acting on polysaccharides. Xanthan lyase was first identified and partially purified in 1987.

Xanthan is a polysaccharide secreted by several different bacterial taxa, such as the plant pathogen Xanthomonas campestris, and it consists of a main linear chain based on cellulose with side chains attached to alternate glucosyl (glucose) residues. These side chains contain three monosaccharide residues. Xanthan lyase is produced by bacteria that degrade this polysaccharide, such as Bacillus, Corynebacterium, Bacteroides, Ruminococcaceae, and Paenibacillus species.

Industrial applications

Xanthan is used in industry as a thickening agent in foods and drinks, as a stabilizing agent for foams, as a means of enhancing oil recovery and in the manufacture of good such as paints, cosmetics and explosives. The use of xanthan lyase as a means of altering the physical properties of xanthans is an area of current research in biotechnology.

Structural studies

As of late 2007, 7 structures have been solved for this class of enzymes, with PDB accession codes 1J0M, 1J0N, 1X1H, 1X1I, 1X1J, 2E22, and 2E24. The enzyme from Bacillus is a monomer consisting of two domains: an alpha helical N-terminal domain, and a C-terminal domain composed of beta sheets. The active site is a deep cleft located between these two domains.

References

1. Sutherland IW (1987). "Xanthan lyases--novel enzymes found in various bacterial species". J. Gen. Microbiol. 133 (11): 3129–34. doi:10.1099/00221287-133-11-3129. PMID 3446747.
2. ^ Hashimoto W, Miki H, Tsuchiya N, Nankai H, Murata K (1 October 1998). "Xanthan lyase of Bacillus sp. strain GL1 liberates pyruvylated mannose from xanthan side chains". Appl. Environ. Microbiol. 64 (10): 3765–8. Bibcode:1998ApEnM..64.3765H. doi:10.1128/AEM.64.10.3765-3768.1998. PMC 106543. PMID 9758797.
3. ^ Ruijssenaars HJ, de Bont JA, Hartmans S (1 June 1999). "A pyruvated mannose-specific xanthan lyase involved in xanthan degradation by Paenibacillus alginolyticus XL-1". Appl. Environ. Microbiol. 65 (6): 2446–52. Bibcode:1999ApEnM..65.2446R. doi:10.1128/AEM.65.6.2446-2452.1999. PMC 91360. PMID 10347025.
4. Ostrowski, Matthew P.; La Rosa, Sabina Leanti; Kunath, Benoit J.; Robertson, Andrew; Pereira, Gabriel; Hagen, Live H.; Varghese, Neha J.; Qiu, Ling; Yao, Tianming; Flint, Gabrielle; Li, James; McDonald, Sean P.; Buttner, Duna; Pudlo, Nicholas A.; Schnizlein, Matthew K.; Young, Vincent B.; Brumer, Harry; Schmidt, Thomas M.; Terrapon, Nicolas; Lombard, Vincent; Henrissat, Bernard; Hamaker, Bruce; Eloe-Fadrosh, Emiley A.; Tripathi, Ashootosh; Pope, Phillip B.; Martens, Eric C. (April 2022). "Mechanistic insights into consumption of the food additive xanthan gum by the human gut microbiota". Nature Microbiology. 7 (4): 556–569. doi:10.1038/s41564-022-01093-0. hdl:11250/3003739. PMID 35365790. S2CID 247866305.
5. Hashimoto W, Nankai H, Mikami B, Murata K (2003). "Crystal structure of Bacillus sp. GL1 xanthan lyase, which acts on the side chains of xanthan". J. Biol. Chem. 278 (9): 7663–73. doi:10.1074/jbc.M208100200. PMID 12475987.

• Sutherland IW (1987). "Xanthan lyases--novel enzymes found in various bacterial species". J. Gen. Microbiol. 133 (11): 3129–34. doi:10.1099/00221287-133-11-3129. PMID 3446747.

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