Collect. Czech. Chem. Commun. 1982, 47, 3470-3474

Amino acid sequence around the reactive cysteinyl residue of chicken pepsin

Jan Pohl, Miroslav Baudyš and Vladimír Kostka

Institute of Organic Chemistry and Biochemistry, Czechoslovak Academy of Sciences, 166 10 Prague 6


The amino acid sequence of the cysteine-containing peptide was determined in two different manners. 1) Chicken pepsin was covalently coupled via its SH-group to Thiopropyl-Sepharose 6B, subjected to peptic digestion and cysteinyl peptides, generated by multiplicity of peptic attack on the sequence ..-Tyr-Tyr-Cys-Asn-Phe-.. (marked by arrows), were eluted by 2-mercaptoethanol. 2) Systematic structure analysis of the tryptic-chymotryptic digest of chicken pepsinogen afforded peptide Tyr-Tyr-Cys-Asn-Phe-Asp-Gly-Ile-Leu-Gly-Leu, whose C-terminal part is highly homologous with other pepsins. These data permitted the cysteinyl residue to be assigned to position 115 (numbered according to hog pepsin A) in a relatively variable region. The same position is occupied by an alanyl residue in hog pepsin A and calf chymosin; this replacement can be considered conservative from the viewpoint of molecular volume.