Primary structure of zymogen of streptococcal proteinase

Abstract

The complete amino acid sequence has been derived for the zymogen of streptococcal proteinase. The protein yielded a unique sequence containing 337 amino acids in a single polypeptide chain. The NH2-terminal residue of the zymogen is aspartic acid and the COOH terminus is proline. The signal peptide commonly associated with the intracellular form of many proteins secreted from eukaryotic cells was absent from the zymogen sequence. The transformation of the zymogen to the enzyme under controlled conditions of proteolysis by trypsin and by streptococcal protease itself involves the removal of 84 amino acid residues from the NH2 terminus of the zymogen. The zymogen-to-enzyme conversion is accompanied by a change in serological specificity. An intermediate, “modified zymogen” formed in the transformation process contains only 12 amino acid residues less than the zymogen but shows the serological reactivity of both the zymogen and the enzyme.