title: An active site peptide from pepsin C.
abstract: Porcine pepsin C is inactivated rapidly and irreversibly by diazoacetyl-dl-norleucine methyl ester in the presence of cupric ions at pH values above 4.5. The inactivation is specific in that complete inactivation accompanies the incorporation of 1mol of inhibitor residue/mol of enzyme and evidence has been obtained to suggest that the reaction occurs with an active site residue. The site of reaction is the beta-carboxyl group of an aspartic acid residue in the sequence Ile-Val-Asp-Thr. This sequence is identical with the active-site sequence in pepsin and the significance of this in terms of the different activities of the two enzymes is discussed.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002247:Carbon Isotopes; D002268:Carboxypeptidases; D002845:Chromatography; D003300:Copper; D003979:Diazonium Compounds / Q000494:pharmacology; D004586:Electrophoresis; D004952:Esters / Q000494:pharmacology; D006454:Hemoglobins; D006863:Hydrogen-Ion Concentration; D007930:Leucine / Q000494:pharmacology; D010434:Pepsin A / Q000032:analysis* / Q000037:antagonists & inhibitors; D010435:Pepsinogens / Q000302:isolation & purification; D010455:Peptides / Q000032:analysis*; D013552:Swine
chemical_list: D002247:Carbon Isotopes; D003979:Diazonium Compounds; D004952:Esters; D006454:Hemoglobins; D010435:Pepsinogens; D010455:Peptides; D003300:Copper; D002268:Carboxypeptidases; D010434:Pepsin A; D007930:Leucine