Physicochemical basis of the recognition process in nucleic acid interactions. I. Interactions of polyuridylic acid and nucleosides.

摘要: Interaction of adenosine and poly U† was studied by equilibrium dialysis, solubility, optical rotation, ultracentrifugation viscosity measurements. Only when a threshold concentration is reached does binding to U take place in co-operative manner, with stacking energy 5 6 kcal. estimated from the adsorption isotherm. The complex thus formed has an ordered structure, presumably helical, and, as expected, molecular weight higher than that U. stability complex, besides being highly dependent on adenosine, influenced ionic strength temperature manner similar system polynucleotide interaction. stoichiometry 1A 2U at 5°C becomes 1U 20°C. This interaction specific, possible involvement N-1,6-amino N-7 hydrogen-bonding scheme, while pentose moiety relatively insignificant role. Other studies our laboratories have shown both purines nucleosides associate form stacks aqueous solution result hydrophobic energy. It proposed these are bound through specific hydrogen bonding. Thus, bonding co-operate complement each other providing driving forces for this