<p> Xanthine-guanine phosphoribosyltransferases catalyse the transfer of the phosphoribosyl group from 5-phospho-alpha-D-ribosyl 1-pyrophosphate to xanthine, guanine and (to a leser extent) hypoxanthine to form GMP, XMP, and IMP, respectively [<cite idref="PUB00037289"/>]. These enzyme uses magnesium as a cofactor and belong to the wider purine/pyrimidinephosphoribosyltransferase family.</p> Xanthine-guanine phosphoribosyltransferase