The specificity of dipeptidyl aminopeptidase I (cathepsin C) and its use in peptide sequence studies.

1. The characterization of cathepsin C as an aminodipeptidase has been confirmed. 2. An extra limitation on its specificity, namely that peptides involving proline as the third residue are immune to the enzyme, has been found. 3. A novel technique of using the enzyme for amino acid sequence determination has been shown to be feasible.