HYDROPHOBIC STACKING OF BASES AND THE SOLVENT DENATURATION OF DNA*

作者：O. Sínanoĝlu, Suheil F. Abdulnur · 发表于：Photochemistry and Photobiology · 年份：1964 · DOI：10.1111/j.1751-1097.1964.tb08156.x · 被引用次数：129 · 研究领域：DNA and Nucleic Acid Chemistry、Electrostatics and Colloid Interactions、Advanced Chemical Physics Studies

Summary The DNA double helix stable in water is denatured by solvents with widely varing properties. To understand quantitatively the role of water in keeping the helix together, the solvent contributions to the unitary free energy difference between random single strands and the helix are calculated for water, MeOH, glycol, formamide, glycerol, ethanol, n‐propanol, and n‐butanol. The property of solvent crucial in denaturation is found to be mainly the enthalpy part of surface tension. The number of molecules solvating the A, T, G, C bases, hence their energy is drastically reduced in going from random coils to the helix. ‘Hydrophobic bonding’ thus results to a large extent from the large surface enthalpy of water. The same interactions may cause the ‘stacking’ of adjacent bases in a single strand of DNA in water. Such stacking may be what makes thymine photodimerization under the action of uv favorable in some thymine hydrate crystals and in aqueous single strand DNA.