On the mechanism and inhibition of DNA cytosine methyltransferases.
We have presented some data from studies of two different DNA cytosine methyltransferases. The first enzyme, M.Hha I, was shown to catalyze 3H exchange from poly(dG.[5-3H]dC), at a rate that is 7 to 10 times greater than the rate of methylation. The exchange is inhibited by AdoHcy in an uncompetitive fashion. This pattern of inhibition suggests an ordered reaction sequence for M.Hha I catalyzed methylation. The second enzyme, M.Hpa II, was demonstrated to make an irreversible adduct with azaC-DNA. The results provide evidence that both enzymes form covalent dihydropyrimidine intermediates during catalysis.
D001483:Base Sequence; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D003850:Deoxyribonuclease I / Q000378:metabolism; D007700:Kinetics; D008745:Methylation; D011089:Polydeoxyribonucleotides; D012436:S-Adenosylmethionine / Q000378:metabolism; D013940:Thymidylate Synthase / Q000378:metabolism; D014316:Tritium
D011089:Polydeoxyribonucleotides; D014316:Tritium; D012436:S-Adenosylmethionine; D004248:DNA (Cytosine-5-)-Methyltransferases; D013940:Thymidylate Synthase; D003850:Deoxyribonuclease I