Amino Acid Sequence of Cyanogen Bromide Fragment CN2 From a Hong Kong Influenza Haemagglutinin Heavy Chain

The amino acid sequence of cyanogen bromide peptide CN2 from the heavy chain (HAl) of the haemagglutinin of the Hong Kong variant A/Memphis/l02/72 has been obtained by direct, automated sequence analysis on the whole fragment and by manual dansyl-Edman degradation of tryptic, peptic and chymotryptic peptides. It was found to contain 92 amino acid residues, including a large, insoluble, tryptic core peptide (residues 62-87). It did not contain any half-cystine residues or carbohydrate. The determination of its structure was complicated by the presence of an Asn-Ile bond at positions 48-49 which was readily cleaved by both trypsin and chymotrypsin.