Studies on the specificity of the cholesterol-binding pancreatic proteinase and identification as human pancreatic...

The proteolytic attack of the cholesterol-binding pancreatic proteinase (CBPP) on the oxidized insulin A and B chains as well as on glucagon was investigated by kinetic studies. The reaction products were isolated by high-pressure liquid chromatography and identified by amino acid analysis. The combined results reveal a pronounced selectivity of CBPP for the peptide bonds at the carboxy ends of Ala, Val, Leu, Ser, His and Thr residues with Ala, Val and Leu most favoured, indicating a close catalytic relationship to porcine pancreatic elastase [Narayanan, A. S. & Anwar, R. A. (1969) Biochem. J. 114, 11-17] and the anionic porcine pancreatic protease E [Kobayashi R., Kobayashi, Y. & Hirs, C. H. W. (1981) J. Biol. Chem. 256, 2460-2465] which resembles human pancreatic elastase 1. The immunological comparison indeed disclosed the identity of CBPP with human pancreatic elastase 1.