The mechanism of decomposition of N-methyl-N-nitrosourea (MNU) in water and a study of its reactions with 2′-deoxyguanosine, 2′-deoxyguanosine 5′-monophosphate and d(GTGCAC)

Add time:07/29/2019    Source:sciencedirect.com

The carcinogenicity of N-methyl-N-nitrosourea (MNU) arises from its ability to methylate DNA. This occurs in an aqueous environment and therefore an appreciation of the mode of decomposition of MNU in water is essential to understanding the mechanism of DNA methylation and its base sequence dependence. The kinetics of MNU hydrolyses are shown to be first order in MNU with a steep rise in rate above pH 8. Using NMR for in situ monitoring of reaction intermediates and products from hydrolyses of [13CO]MNU, [15NH2]MNU and [13CH3]MNU, it is proved that base-induced hydrolysis of MNU is initiated by deprotonation at the carbamoyl group. The critical reactive species are shown to be the methyldiazonium ion (Me-N2+) and cyanate (NCO−). Investigations of reactions of [13CH3]MNU with 2′-deoxyguanosine (dGuo) and 2′-deoxyguanosine 5′-monophosphate (dGuo-5P) showed that: a) the site of methylation of dGuo is highly pH-dependent (relatively more N-1 and O6-methylation compared to N-7 occurs at higher pH); b) the principal site of methylation of dGuo-5P by MNU is at phosphate; c) incorporation of deuterium into methyl groups occurs in D2O at higher pH. Methylation of the oligonucleotide d(GT[15N]GCAC) by MNU in D2O showed partial deuteriation of the N7-methyl groups of the guanines, whilst methylation by MNU in water indicated no significant preference for either guanine with respect to N7-methylation.

We also recommend Trading Suppliers and Manufacturers of 7-methyl-2'-deoxyguanosine 3'-monophosphate (cas 123497-14-3). Pls Click Website Link as below: cas 123497-14-3 suppliers

Prev:The crystal and molecular structrue of 8-methyladenosine 3′-monophosphate dihydrate
Next:Biosynthesis of (deoxy)guanosine-5′-triphosphate by GMP kinase and acetate kinase fixed on the surface of E. coli)