title: Mechanism of pepsin-catalyzed aminotranspeptidation reactions.
abstract: 1. The tetrapeptide Ala2-Nph2 (where Nph = p-nitrophenylalanyl) is treated by porcine pepsin to study the mechanism of aminotranspeptidation reactions. 2. The major initial product is Ala2-Nph and the major transpeptidation products are Nph2 and Nph3 accompanied by some Nph, a little Nph4, Ala2-Nph3 and Ala2-Nph4. 3. Oligomers of Nph greater than tetramers are formed near the end of the reaction. 4. In presence of [3H]Nph, no incorporation of Nph into the transpeptidation products is observed. 5. 18O-labeling shows extensive incorporation of 18O atoms from [18O]water in the carbonyl oxygens of Nph residues.
authors.affiliation: Department of Biochemistry, Faculty of Science, Alexandria University, Egypt.
authors.forename: M
authors.initials: M
authors.lastname: Balbaa
authors.forename: M
authors.initials: M
authors.lastname: Blum
authors.forename: T
authors.initials: T
authors.lastname: Hofmann
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000737:chemistry*; D000818:Animals; D002384:Catalysis; D002851:Chromatography, High Pressure Liquid; D008969:Molecular Sequence Data; D010103:Oxygen Isotopes; D010434:Pepsin A; D010649:Phenylalanine / Q000031:analogs & derivatives; D013552:Swine
chemical_list: D000596:Amino Acids; D010103:Oxygen Isotopes; C040239:4-nitrophenylalanine; D010649:Phenylalanine; D010434:Pepsin A