The influence of N7 substituents on the stability of N7-alkylated guanosines.
Guanosine alkylated at the 7-position readily decomposed by imidazole ring opening and depurination. There is a direct correlation between the electron-withdrawing effects, expressed as the Taft substituent constant sigma*, of various alkylsubstituents in 7-position and the respective acid dissociation constants and chemical stabilities of 7-alkylated guanosines. The respective values for the slopes of the regression lines were rho* = +1.89 for imidazole ring opening and rho* = +0.175 for the depurination reaction. Unknown Taft constants can be determined from the sigma*/pKa regression line.
D000478:Alkylation; D002384:Catalysis; D055598:Chemical Phenomena; D002621:Chemistry; D002851:Chromatography, High Pressure Liquid; D003500:Cyclization; D004583:Electrons; D006151:Guanosine / Q000031:analogs & derivatives*; D006863:Hydrogen-Ion Concentration; D007093:Imidazoles; D013329:Structure-Activity Relationship
D007093:Imidazoles; D006151:Guanosine