25] Isolation of the major envelope glycoprotein of avian myeloblastosis virus

Abstract

Several glycoproteins associated with virus envelopes have been shown to possess an amphipathic structure, similar to that proposed for human erythrocyte glycophorin. These proteins contain hydrophobic regions rich in amino acids with lipophilic side chains, and hydrophilic regions, which are usually glycosylated. The solubilization of these proteins show different degrees of difficulties depending on the hydrophobic interactions between the proteins and other components of the membranes. Several methods involving the use of detergents, guanidine hydrochloride, and chloroform–methanol mixtures can be used to achieve purification of the major glycoproteins of avian oncornaviruses. For the isolation of the major envelope glycoprotein of avian myeloblastosis virus, the original method of Marchesi and Andrews is applied to extract the glycoprotein with lithium diiodosalicylate followed by ion-exchange chromatography in the presence of nonionic detergent. The procedure is reproducible and results in almost quantitative recovery of the glycoprotein in a biologically active water-soluble form.