title: Amino-acid sequence of porcine pepsin.
abstract: As the culmination of several years of experiments, we propose a complete amino-acid sequence for porcine pepsin, an enzyme containing 327 amino-acid residues in a single polypeptide chain. In the sequence determination, the enzyme was treated with cyanogen bromide. Five resulting fragments were purified. The amino-acid sequence of four of the fragments accounted for 290 residues. Because the structure of a 37-residue carboxyl-terminal fragment was already known, it was not studied. The alignment of these fragments was determined from the sequence of methionyl-peptides we had previously reported. We also discovered the locations of activesite aspartyl residues, as well as the pairing of the three disulfide bridges. A minor component of commercial crystalline pepsin was found to contain two extra amino-acid residues, Ala-Leu-, at the amino-terminus of the molecule. This minor component was apparently derived from a different site of cleavage during the activation of porcine pepsinogen.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D003488:Cyanogen Bromide; D006868:Hydrolysis; D010434:Pepsin A / Q000032:analysis*; D010446:Peptide Fragments / Q000032:analysis; D013552:Swine
chemical_list: D010446:Peptide Fragments; D010434:Pepsin A; D003488:Cyanogen Bromide