Purification and characterization of goat pepsinogens and pepsins

Three type-ii and two type-C pepsinogens, namely, pepsinogens A-1, A-2, A-3 , C-1, and C-2, were purified from adult goat abomasum. Their relative leve ls in abomasal mucosa were 27, 19, 14, 25, and 15%, respectively. Amino aci d compositions were quite similar between isozymogens of respective types, but different between the two types especially in the Glx/Asx and Leu/Ile r atios. NH2-terminal amino acid sequences of pepsinogens A-3 and C-2 were SF FKIPLVKKKSLRQNLIEN- and LVKIPLKKFKSIRETM-, respectively. Pepsins A and C sh owed maximal hemoglobin-digestive activity at around pH 2 and 3, respective ly, and specific activities of pepsins C were higher than those of pepsins A. Two subtypes of pepsin A were obvious, namely pepsin A-2/3 which maintai ns its activity in the weakly acidic pH region over pH 3 and pepsin A-1, wh ich does not. Hydrolysis of oxidized insulin B chain by goat pepsins A occu rred primarily at Ala14-Leu15 and Leu15-Tyr16 bonds. (C) 1999 Elsevier Scie nce Inc. All rights reserved.