DEGRADATION OF TURNIP YELLOW MOSAIC VIRUS BY FREEZING AND THAWING IN VITRO - A NEW METHOD FOR STUDIES ON INTERNAL ORGANIZATION OF VIRAL COMPONENTS AND FOR ISOLATING NATIVE RNA

Turnip yellow mosaic virus (TYMV) in water solution was degraded into its constituent RNA and protein components after freezing at -75° and subsequent thawing. This behavior of the virus has been utilized to develop a rapid and simple method for preparative isolation of its RNA. TYMV-RNA prepared by this new method was centrifugally more homogeneous than RNA prepared by phenol extraction before brief heating at 65°. After heating, the percentages of homogeneous, rapidly sedimenting RNA were the same. The preparations were also equally infectious. It has furthermore been demonstrated that the freezing degradation method is particularly suitable for use in studies of the macromolecular organization of the virion. Potentiometric titrations of TYMV and its protein capsids, before and after freezing, demonstrated the presence of prototropic groups on the RNA and protein, which are normally involved in, or hidden because of, the integration of these components as the virion. © 1969.