The Preparation of Trypsins and Chymotrypsins From Bovine and Porcine Residues After Insulin Extraction

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Abstract
Bovine and porcine pancreatic residue, remaining after the extraction of insulin, has been used to prepare a proteinase powder. This powder was used as a source of trypsin and chymo-trypsin. The individual enzymes were isolated and purified by chromatography on sulfopropyl (SP)-Sephadex C-25 and affinity chromatography on soybean trypsin inhibitor (STI)-Sepharose. The bovine proteinase powder contained a-chymotrypsin, trypsin and chymotrypsin B in the ratio 5:2:1. The porcine powder contained cationic trypsin, anionic trypsin and cationic chymotrypsin in the ratio 5 : 1. 4 : 3. The isolated enzymes were characterized and found to be identical with enzymes isolated from fresh tissue with the exception of porcine chymotrypsin. Porcine cationic chymotrypsin was isolated as two distinct forms, A-l and A-2, which appear to be different activation products of porcine chymotrypsinogen A. Both forms resemble bovine a-chymotrypsin, a three chain structure, rather than porcine chymo-trypsin A, a two chain structure. Furthermore, the B-chain appears to be cleaved, possibly at residues Phe89-Lys90.

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