Completion of the amino acid sequence of a Hong Kong influenza hemagglutinin heavy chain: Sequence of cyanogen bromide fragment CN1

Abstract

The amino acid sequence of cyanogen bromide fragment CN1 from the hemagglutinin heavy chain (HA 1) of the Hong Kong influenza virus A/Memphis/102/72 has been determined by manual Edman degradation of tryptic and chymotryptic peptides and automated sequenator analysis of whole HA 1 after removal of the N-terminal pyroglutamic acid blocking group with calf liver pyroglutamate aminopeptidase. CN1 is the N-terminal cyanogen bromide peptide of HA 1 and extends from residues 1 to 168. The elucidation of the sequence of CN1 completes the amino acid sequence of A/Memphis/102/72 HA 1. This Hong Kong heavy chain contains a total of 328 amino acid residues and when compared with the HA 1 polypeptides of other influenza strains has an additional 10 residues at its N terminus including a glycosylated asparagine residue. It contains six glycosylated asparagine residues, five of which occur in CN1 at residues 8, 22, 38, 81, and 165 and one in CN3 at residue 285. No carbohydrate groups were found attached to serine or threonine residues. The Hong Kong HA 1 contains nine half-cystine residues, six of which are in CN1 at positions 14, 52, 64, 76, 97, and 139 and three in CN3 at positions 277, 281, and 305. The structure is discussed in relation to the available published data on the hemagglutinins from other strains of influenza virus and recent developments in the analysis of antigenic shift and drift.