Isolation of proteins by gel filtration in 6 m guanidinium chloride: Application to RNA tumor viruses

Abstract

Separation of RNA tumor virus proteins by gel filtration in 6 m guanidinium chloride indicates that this method will effectively separate polypeptides in milligram amounts whose molecular weights differ by as little as 15 percent. Such separations are achieved because proteins in 6 m guanidinium chloride have a random coil conformation with diffusion coefficients considerably smaller than the corresponding native proteins. Consequently, protein bands that emerge from a gel filtration column in 6 m guanidinium chloride are remarkably sharp. A 60–70% yield of renatured RNA tumor virus proteins could be obtained following dialysis against a dilute solution of mercaptoethanol. The major proteins of avian RNA tumor viruses were obtained as pure components by gel filtration in 6 m guanidinium chloride. Mammalian RNA tumor viruses appear to have a more complex protein structure, since, in some cases, additional purification was required to obtain the pure proteins. This method of protein separation might be used as the initial stop in the isolation of components from other biological macrostructures.