Springer Online Journal Archives 1860-2000
Chemistry and Pharmacology
Abstract The thermodynamic quantities associated with ionization of the N1 and N9 protons of adenine have been calorimetrically determined as a function of temperature. The ΔH values for proton dissociation of these groups, with pK values of 4.19 and 9.92, were found to be 5.1 and 9.1 kcal/mole, respectively, at 25°C, μ=0.025. The ΔC p values for proton dissociation of these groups were estimated to be −11 and −17 cal/mole-deg. These results indicate that the large heat capacity changes observed during conformational transitions of polynucleotides are not the result of ionization of the bases.
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