Elektrophoretische Untersuchungen der Α-Proteine dreier Tabakmosaikvirus-Stämme

Abstract

In the present paper we studied the relations between the mobility of the RNA-free proteins of three strains of tobacco mosaic virus and the pH. The proteins were prepared by alcaline degradation of the native virus. We used a carefully purified degradation product for the electrophoretic measurements, the so-called Α-protein (sedimentation constant 4,6 S; molecular weight about 90 000). We verified by sedimentation measurements and electron microscopy that this protein within the pH-range of about 2,5 - 6,0 ist reaggregated into rods. The electrophoretic mobility of these RNA-free rods is identical with that of the respective native virus (fig. 1). Below pH 2,5 and above pH 6,0 the mobility differs greatly from that of the native virus (fig. 1 and 2). To explain these results it is presumed, that the electrophoretic mobility is determined only by those acid and basic groups which are situated on or near the surface of the migrating particle. Since in this case the RNA would be unable to influence the mobility of the native virus particles, the identical mobility of the complete virus and that of the respective RNA-free rod-like aggregates of Α-protein becomes understandable. The changes in the mobility of the RNA-free proteins at about pH 2,5 and 6,0 are thus explained by a non homogeneous distribution principally of the basic groups. According to this assumption the basic groups would be situated mainly inside and not near the surface of the rods.