Some properties of decomposition products of potato virus X

The small surface potential of potato virus X (PVX) probably accounts for its tendency to become insoluble during purification. The protein produced by splitting the virus with alkali (at about pH 10) has a higher surface potential than the virus: electrophoretic mobility of the protein in pH 7.0 phosphate buffer is −0.15 μ/sec/volt/cm, compared with −0.04 for that of the virus. The nucleic acid, mobility −1.7, is not infective when it is separated electrophoretically from alkali-split virus. The protein, but not the nucleic acid, precipitates with PVX antiserum. Material with the same electrophoretic mobility as protein produced by splitting the virus with alkali is sometimes detectable in sap from infected plants. Treatments that aggregate protein fragments from tobacco mosaic virus into viruslike rods produce amorphous precipitates of PVX protein that do not redissolve; this difference may reflect the different ways in which surface charges are distributed on the protein from the two viruses. The nucleic acid seems not to contribute to the surface potential of either virus. Disrupting PVX with phenol gives water-soluble material consisting predominantly of nucleic acid; freshly made preparations have some infectivity, which is not conferred by residual intact virus particles.