Order of the CNBr fragments in the adenovirus hexon protein.

The fractionation and the amino acid sequence of 26 unique CNBr fragments from ['4C]carboxymethylated hexon protein of adenovirus type 2 have been described (1, 2 ) . In addition, four fragments obtained by acid cleavages at Asp-Pro bonds have been detected (1, 2) . Sequence analysis of peptides generated with proteolytic enzymes has furthermore provided evidence for the existence of three additional unique methionine residues, The results thus suggest a total of 28 methionine residues in the hexon polypeptide. All these residues have been ordered; 26 have been identified in peptides containing overlapping regions around the methionines and 18 have been identified by DNA sequence analysis of selected regions in the hexon gene. The structure around 17 methionine residues has been determined by both methods. In this communication we present data from both peptide and DNA sequence analysis which allow the ordering of all CNBr fragments. Although not completely excluded, there is no evidence for additional methionine residues. Therefore, based on the present order, and the structure of individual CNBr fragments ( 1,2) , an amino acid sequence for hexon may be deduced and correlated with the hexon gene (3). The nomenclature of all known methionine residues and CNBr peptides is summarized in Table I.