Amino acid composition of the protein components of influenza virus A

Abstract

A study has been made of the amino acid composition of the three protein components, soluble antigen, hemagglutinin, and membrane protein released from influenza virus particles by treatment with ether. The results are compared with analyses of similar proteins present in cytoplasmic particles released from normal cells. In all the proteins analyzed eighteen amino acids were found, and nine of these (alanine, aspartic acid, glycine, isoleucine, leucine, methionine, phenylalanine, serine, and tyrosine) were present in all the proteins in amounts that did not differ by more than the experimental error (±10%) of the method. Significant differences were found in the content of arginine, cystine, glutamic acid, histidine, lysine, proline, threonine, tryptophan, and valine in the various proteins examined. The soluble antigen protein differed from all the other proteins tested in its content of arginine (9.8%), which was almost double that found in any of the others. The virus hemagglutinin and membrane proteins appeared to have the same composition. This closely resembled the composition of normal cell membrane protein but differed from it in having a much higher content of histidine.