Interactions of turnip yellow mosaic virus with quaternary ammonium salts

Abstract

In the presence of quaternary ammonium salts of the general structure C n H 2 n+1 N · Me 3Br, rapid degradation of turnip yellow mosaic virus takes place at pH 9 and 20°C. In contrast, nucleic acid free protein shells of the virus are much more stable under the same conditions. The way in which the rate of the reaction depends on the pH and on the temperature of the reaction mixture and on the concentration and the structure of the quaternary ammonium salts used has been investigated. A large increase of the rate was found when n = 6, while only insignificant increases could be detected when n < 6. The degradation by means of the quaternary salts has been compared with the behaviour of the virus in solutions of alkali salts. Interaction of the virus with sodium dodecyl sulphate, spermine, a primary and a tertiary amine, have been studied; as with the quaternary ammonium salts with n < 6 no significant increases of the rate were found. As to the mechanism of the degradation, it is suggested that the quaternary ammonium ions cause conformational changes of the nucleic acid inside the virus particles, resulting ultimately in degradation of the virus. This view is based among other considerations on the sedimentation behaviour of free virus nucleic acid in solutions of quaternary ammonium salts.