Guanosine 5'-Monophosphate Catalyzed Hydrolisis of Diastereomeric Benzopyrene-7,8-diol 9,10-Epoxides

Article abstract of DOI:10.1021/ja00375a026

The rates of reaction of 7β, 8α-dihydroxy-9β,10β-epoxy-7,8,9,10-tetrahydrobenzopyrene and 7β,8α-dihydroxy-9α,10α-epoxy-7,8,9,10-tetrahydrobenzopyrene in aqueous dioxane solutions in the presence of 5'-guanosine monophosphate (5'-GMP) and guanosine (G) have been determined. 5'-GMP in the monohydrogen form (GMPH(-)) exhibits pronounced general acid catalysis in the hydrolysis of these epoxides under conditions where the corresponding nucleoside G is unreactive.Although the pK_a values for GMPH(-) and inorganic dihydrogen phosphate ion (H2PO4(-)) are very similar, GMPH(-) is 60-80 times more efficient than H2PO4(-) in catalyzing the hydrolysis of the diol epoxides.Significant solvent effects on both GMPH(-) and H2PO4(-) have been observed.