Pyrimidine ring, opening, review

Pyrimidinediones s. Uracils Pyrimidine ring, opening, review 31, 463... 

A key enzyme in pyrimidine biosynthesis, thymidylate synthetase, catalyzes the reductive methylation of 2 -deoxyuridylate (dUMP) to thymidylate (dTMP) with the concomitant conversion of 5,10-methylene-H4-folate to 7,8-dihydrofolate. The cofactor serves both as a 1-carbon carrier and a reductant. There is substantive evidence based on direct and indirect studies with the inhibitor 5 -fluoro-2 -deoxyuridylate, which will not be reviewed here, that the dUMP is covalently bound to the enzyme, possibly through a thiol group [59]. The intermediate ternary complex is hypothesized to have the following structure (10), where the CH2 unit is attached through the N-5 of H4-folate. The ring opening of the 5,10-methylene-H4-folate is... 

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