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In enzymology, a xanthine phosphoribosyltransferase (EC 2.4.2.22) is an enzyme that catalyzes the chemical reaction

XMP + diphosphate ${\displaystyle \rightleftharpoons }$ 5-phospho-alpha-D-ribose 1-diphosphate + xanthine

Thus, the two substrates of this enzyme are XMP and diphosphate, whereas its two products are 5-phospho-alpha-D-ribose 1-diphosphate and xanthine.

This enzyme belongs to the family of glycosyltransferases, specifically the pentosyltransferases. The systematic name of this enzyme class is XMP:diphosphate 5-phospho-alpha-D-ribosyltransferase. Other names in common use include Xan phosphoribosyltransferase, xanthosine 5'-phosphate pyrophosphorylase, xanthylate pyrophosphorylase, xanthylic pyrophosphorylase, XMP pyrophosphorylase, 5-phospho-alpha-D-ribose-1-diphosphate:xanthine, phospho-D-ribosyltransferase, 9-(5-phospho-beta-D-ribosyl)xanthine:diphosphate, and 5-phospho-alpha-D-ribosyltransferase. This enzyme participates in purine metabolism.

Structural studies

As of late 2007, 6 structures have been solved for this class of enzymes, with PDB accession codes 1A95, 1A96, 1A97, 1A98, 1NUL, and 2FXV.

References

• Krenitsky TA, Neil SM, Miller RL (1970). "Guanine and xanthine phosphoribosyltransfer activities of Lactobacillus casei and Escherichia coli. Their relationship to hypoxanthine and adenine phosphoribosyltransfer activities". J. Biol. Chem. 245 (10): 2605–11. doi:10.1016/S0021-9258(18)63113-8. PMID 4910918.

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