<unk>  catalyzes the second reaction of the Leloir pathway of<unk>  metabolism through ping pong bi-bi kinetics with a double displacement mechanism. This means that the net reaction consists of two reactants and two products (see the reaction above) and it proceeds by the following mechanism: the enzyme reacts with one substrate to generate one product and a modified enzyme, which goes on to react with the second substrate to make the second product while regenerating the original enzyme. In the case of<unk> , the His166 residue acts as a potent nucleophile to facilitate transfer of a nucleotide between UDP-hexoses and hexose-1-phosphates. #UDP-glucose + E-His Glucose-1-phosphate + E-His-UMP<unk> -1-phosphate + E-His-UMP UDP-galactose + E-His Two-step action of<unk> . Image adapted from
Galactose-1-phosphate uridylyltransferase
Iduronate-2-sulfatase
Galactosylceramidase
Xanthine oxidase
Glucuronosyltransferase
Asparaginase
Thymidine phosphorylase
Phenylalanine hydroxylase