Amino acid sequence around the cysteine residues of pigeon egg-white lysozyme: comparative study with other type c lysozymes

The cysteine-containing tryptic peptides of pigeon egg-white lysozyme have been purified by reverse-phase chromatography and thin-layer chromatography and electrophoresis on cellulose plates. They contain the eight cysteine residues of the protein. The amino acid sequence of these peptides reveals the existence of 24 differences in comparison to the homologous regions in hen egg-white lysozyme, among the 53 sequenced residues. The sequence data are compared to the corresponding ones in other type c lysozymes. According to this study, the pigeon lysozyme exhibits ten substitutions not observed in any other type c lysozyme. Pigeon lysozyme is the most different type c lysozyme from birds, according to the data on primary structure.