title: Amino acid sequence at the reactive site of human alpha 1-antichymotrypsin.
abstract: The reactive site of human alpha 1-antichymotrypsin has been identified as encompassing a leucyl-seryl bond at the apparent P1 and P'1 positions. This has been determined by dissociation of complexes of the inhibitor with bovine alpha-chymotrypsin, followed by identification of new NH2-terminal sequences, as well as by proteolytic inactivation by porcine pancreatic elastase. The latter results in peptide bond cleavage between the apparent P5 and P4 positions of the inhibitor, yielding a fragment whose sequence overlaps with that obtained through complex dissociation. Some homology with the sequence obtained and that already reported for both antithrombin III and alpha 1-proteinase inhibitor can be noted.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002918:Chymotrypsin / Q000037:antagonists & inhibitors* / Q000302:isolation & purification / Q000494:pharmacology; D006801:Humans; D010179:Pancreas / Q000201:enzymology; D010196:Pancreatic Elastase / Q000037:antagonists & inhibitors; D010446:Peptide Fragments / Q000032:analysis; D013552:Swine; D014361:Trypsin Inhibitors; D000514:alpha 1-Antichymotrypsin
chemical_list: D010446:Peptide Fragments; D014361:Trypsin Inhibitors; D000514:alpha 1-Antichymotrypsin; D002918:Chymotrypsin; D010196:Pancreatic Elastase