title: Characterization of the inactive fragment resulting from limited proteolysis of human alpha1-proteinase inhibitor by Crotalus adamanteus proteinase II.
abstract: The inactive 50,000-dalton fragment of human plasma alpha1-proteinase inhibitor resulting from limited proteolysis of the inhibitor by Crotalus adamanteus proteinase II has been isolated and partially characterized. The amino acid composition of the inactivated inhibitor indicates the loss of a peptide fragment from the intact inhibitor. Both intact and inactivated inhibitor contain COOH-terminal lysine. However, the NH2 terminus of the intact inhibitor is Glx, whereas that of inactivated inhibitor is methionine. NH2-terminal analysis of the inactive inhibitor fragment revealed the following sequence: -Met-Phe-Leu-Glu-Ala-Ile-Pro-Met-Ser-Ile-Pro-Pro-Gln-Val-Lys-Phe-Asn. The data show that the venom proteinase has inactivated alpha1- proteinase inhibitor by cleavage of a single bond which differs from that reported for trypsin or papain.
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D003435:Crotalid Venoms; D010450:Endopeptidases; D006801:Humans; D008970:Molecular Weight; D010206:Papain; D010446:Peptide Fragments / Q000032:analysis; D011480:Protease Inhibitors; D014357:Trypsin
chemical_list: D000596:Amino Acids; D003435:Crotalid Venoms; D010446:Peptide Fragments; D011480:Protease Inhibitors; D010450:Endopeptidases; D014357:Trypsin; D010206:Papain