Temperature dependence of the hydrogen ion equilibria in poly(riboadenylic acid)

Abstract

Abstract Hydrogen ion titration curves have been obtained for poly (riboadenylic acid) (poly A) at temperatures of 0–40°C, and ionic strengths of 0.001, 0.01, and 0.15. Where comparable, the data are in general agreement with those previously reported by other investigators. Correlations between the titration data and thermal denaturation curves have been obtained. Formation of a two‐stranded helix is catalyzed by the uptake of protons by the adenine base. Partial protonation of the base is required for formation of the two‐stranded helix, but under appropriate conditions it is stable at degrees of ionization less than 0.2. The degree of ionization required for formation of the two‐stranded helix increases with temperature and decreases with ionic strength.