In enzymology, a thiamine-phosphate diphosphorylase () is an enzyme that catalyzes the chemical reaction 2-methyl-4-amino-5-hydroxymethylpyrimidine diphosphate + 4-methyl-5-(2-phosphono-oxyethyl)thiazole diphosphate + thiamine monophosphate The two substrates of this enzyme are 2-methyl-4-amino-5-hydroxymethylpyrimidine diphosphate and 4-methyl-5-(2-phosphono-oxyethyl)thiazole; its two products are diphosphate and thiamine monophosphate. This enzyme belongs to the family of transferases, specifically those transferring aryl or alkyl groups other than methyl groups. This enzyme is on the biosynthetic pathway to thiamine. Nomenclature The systematic name of this enzyme class is 2-methyl-4-amino-5-hydroxymethylpyrimidine-diphosphate:4-methyl-5-(2 -phosphoethyl)thiazole 2-methyl-4-aminopyrimidine-5-methenyltransferase. Other names in common use include thiamine phosphate synthase, thiamine phosphate pyrophosphorylase, thiamine monophosphate pyrophosphorylase, and TMP-PPase. Structural studies As of late 2007, 9 structures have been solved for this class of enzymes, with PDB accession codes , , , , , , , , and . References Further reading EC 2.5.1 Enzymes of known structure