What is involved in formation of d-TMP from d-UMP: (PGI June 2007): (A) N5, N10- methylene tetra hydrofolate, (B) Form imino folate, (C) N5 formyl folate, (D) Dihydro folate
Answer is A. Ans: A (N5, N10, Methylene tetrahydrofolate) Lippincott 4th/303-04: SaysdUMP is converted to dTMP by thymidylate synthase, which uses N5;N10'-methylene tetrahydrofoiate Q as the source of the methyl group. This is u nasal reaction in that tetrahydrofoiate {THF) contributes not only a one carbon unit but also fwo hydrogen atoms from the pteridine ring, resulting in the oxidation of THF to dihydrofolate (DHFJ.Inhibitors of thymidylate syn those includes thymine a nalogs such as 5-fluroruracil(DHF) can be reduced to THF by dihvdrofolate reductaseQ an enzyme that is inhibited in the presence of drugs such as methotrexateQ