Thymidylate Synthase

Thymidylate synthase (TS) is an enzyme catalyzing the sole de novo pathway for the biosynthesis of deoxythymidine monophosphate (dTMP) in which deoxyuridine monophosphate (dUMP) is reductively methylated by 5,10-methylenetetrahydrofolate (CH2H4folate) with the generation of dTMP and dihydrofolate (H2folate). TS has been found in a wide range of sources, including bacteria, bacteriophage, yeast, viruses and vertebrates, where it is usually a dimer consisting of identical subunits (30 to 35 kDa each). However, protozoal TS is a bifunctional protein with dihydrofolate reductase (DHFR) on the same polypeptide chain, where TS and DHFR domains are located on the carboxy terminus and amino terminus respectively.