Human pancreatic proelastase 2. Sequence of the activation peptide.

The N-terminal sixteen residues of the amino acid sequence of reduced and alkylated human pancreatic proelastase 2 have been established, and N-terminal amino acid residue has been shown to be carboxymethylcysteine. A peptide containing an amino acid sequence corresponding to the first twelve residues of proelastase 2 was isolated following activation of proelastase 2 with trypsin, performic acid oxidation, and gel filtration. This peptide was not released prior to performic acid oxidation, suggesting that it remains attached to the major peptide chain via a disulfide bond containing the N-terminal half-cysteine in a manner similar to that found for chymotrypsinogens. However, the amino acid sequence of the activation peptide is not strongly homologous to either porcine chymotrypsinogen A or porcine proelastase 1.