The amino acid sequence of a Hong Kong influenza haemagglutinin light (HA2) chain.

The amino acid sequence of the Hong Kong haemagglutinin light chang (HA2:222 residues) is nearly complete, lacking only the definition of a highly aggregated region near the carboxyl terminal end of the chain. This unsequenced area of approx. 25 residues occurs near the carboxyl terminal end of cyanogen bromide peptide CN-I, whose structure determination is discussed in this paper. All 1/2-cystine residues present in HA2 occur in CN-I, as a proximal cluster involving residues 137, 144 and 148, and as a distal cluster involving four other 1/2-cystine within peptides. The single glycosylated asparagine in HA2 also occurs in CN-I; the carbohydrates moiety is complex. The structure of HA2 is discussed in terms of its properties, and compared with published data from haemagglutinins from other influenza strains.