The Structure of the Small Polypeptide Chain of the Hemagglutinin of an Asian Influenza Virus Japan 305/57 — Bellamy/42 (H2N1)

Summary

The hemagglutinin of the influenza virus variant A/Japan/305/57 — A/Bellamy/42 (H2N1) was isolated from virus particles following digestion with Bromelain (EC 3.4.22.4) and purified by sucrose density gradient centrifugation. The 2 component polypeptide chains BHA₁ and BHA₂ were separated, following full reduction and alkylation of cysteine residues by molecular sieving on Sephadex G-100. The smaller polypeptide chain BHA₂ was shown to contain 165 amino acid residues including 3 cysteine, 5 methionine, 6 arginine and 12 lysine residues. Six cyanogen bromide (CNBr) peptides which account for the total composition of the polypeptide have been purified by molecular sieving and ion exchange chromatography. These peptides have been aligned by sequence analysis of the CNBr peptides and by structural analysis of methionine containing protease generated overlap peptides. The amino terminal 9 residues of BHA₂ are shown to be hydrophobic. Residues 14–26 contain 2 tryptophan and 3 tyrosine residues. Glycine residues are located at positions 1, 4, 8, 12, 13, 16, 20, 23, 31 and 33. The 3 cysteine residues are located near the carboxyl terminus of the polypeptide.