Guanine and 7-methylguanine amino proton exchange rates as a function of buffer pK: implications for the exchange mechanism.
Using the stopped-flow kinetic method we have measured the deuteration rate of the amino protons in 2'deoxyguanosine 5'monophosphate and 7-methylguanosine 5'monophosphate. For both compounds the exchange rates are accelerated with increasing concentration of a large number of buffers with widely differing pKs. The results obtained, in conjunction with a theoretical model study, give rise to serious doubts concerning the normally accepted mechanism of amino proton exchange involving a pre-protonation at N7.
D002021:Buffers; D003848:Deoxyguanine Nucleotides; D006147:Guanine / Q000031:analogs & derivatives*; D007700:Kinetics; D011522:Protons; D013816:Thermodynamics
D002021:Buffers; D003848:Deoxyguanine Nucleotides; D011522:Protons; D006147:Guanine; C008450:7-methylguanine; C007257:2'-deoxyguanosine 5'-phosphate