Initial Kinetics of Degradation of MS2 Ribonucleic Acid by Ribonuclease, Heat and Alkali and the Presence of Configurational Restraints in this Ribonucleic Acid

Abstract

The initial kinetics of degradation of MS2 RNA by ribonuclease, heat and alkali were followed by the exponential decline in RNA infectivity. The turnover number of pancreatic ribonuclease is independent of RNA concentration between 10^(11) and 10^(15) RNA molecules per ml. Inactivation at high pH is almost proportional to the hydroxyl ion concentration between pH 11 and 12·3. The activation energy for thermal inactivation at neutral pH is 22 kcal./mole. MS2 RNA possesses no covalent configurational restraints, as shown by the correspondence between the decline in infectivity produced by ribonuclease and the production of RNA fragments, by the coincident sedimentation of the RNA infective material and the bulk RNA under a variety of conditions, and by the presence of only one component when the RNA is sedimented under denaturing conditions. The RNA chain does form intramolecular hydrogen bonds, which under certain conditions give rise to a multiplicity of discrete, infective components.