Activity of Bovine Pancreatic Ribonuclease A in Mixed Solvent Systems

Abstract

IT has been shown that bovine pancreatic ribonuclease may be dissolved in organic solvents with full recovery of the activity after removal of the solvent1. We have found that ribonuclease A retains its activity in the presence of high concentrations of many organic solvents and have utilized this property for investigating its mode of action. If the solvent used is methanol then the products of the action of ribonuclease on cytidine-2′,3′-phosphate are cytidine-3′-phosphate and cytidine-3′-phosphate methyl ester as previously observed by Heppel and Whitfeld2. As the mole fraction of methanol is raised, methanolysis increases and hydrolysis decreases as shown in Fig. 1. This behaviour is consistent with competition between methanol and water for a site on the enzyme.