Reactions of nucleic acids and their components. Part V. The reaction of acid imino groups of purine, thymine, and adenine with formaldehyde

Abstract

Ionisation and thermodynamic constants of the acid imino groups of purine, thymine, and adenine have been evaluated, and the reaction of these groups with formaldehyde followed using the pH elevation and pH-statting methods and spectrophotometry. The free-energy changes, entropy changes, and heats of reaction have been evaluated over the temperature range of 20–50°. The reaction attained equilibrium rapidly. The results are interpretable in terms of a reversible reaction of one formaldehyde molecule with the respective acid imino group.