Human neutrophil proteinase 3: Mapping of the substrate binding site using peptidyl thiobenzyl esters

A series of peptidyl thiobenzyl esters was used to map the active site of human leukocyte proteinase 3. The steady-state kinetics parameters reveal the following features regarding the substrate specificity of proteinase 3 and its putative active site: (a) the preferred P 1 residue is a small hydrophobic amino acid such as aminobutyric acid, norvaline, valine or alanine (in decreasing order of preferences (b) the enzyme has an extended active site, and (c) its active site is similar to that of the related serine proteinases leukocyte elastase and leukocyte cathepsin G.