title: Evidence for presence of peptide alpha-amidating activity in pancreatic islets from newborn rats.
abstract: The peptide alpha-amidating activity of a homogenate of pancreatic islets from 5-7-day-old rats was investigated, using as substrate a glycine-extended tripeptide (D-Tyr-Val-Gly). The islet homogenates had a marked amidating activity, with a Km of 57 microM, a Vmax. of 185 pmol/h per mg and a pH optimum of 7.0. This activity was dependent on the presence of ascorbic acid (in the reduced form) and Cu2+, the optimum concentrations being 4 mM and 40 microM respectively. On fractionation of the homogenate, the highest specific activity was found in the soluble fraction. Exocrine pancreatic tissue showed very low levels of amidating activity.
authors.affiliation: Department of Medical Physiology C, University of Copenhagen, Denmark.
authors.forename: A
authors.initials: A
authors.lastname: Zhou
authors.forename: N A
authors.initials: NA
authors.lastname: Thorn
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000831:Animals, Newborn / Q000378:metabolism*; D001205:Ascorbic Acid / Q000494:pharmacology; D003300:Copper / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D007515:Islets of Langerhans / Q000201:enzymology*; D006899:Mixed Function Oxygenases; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes; D009842:Oligopeptides / Q000378:metabolism; D000587:Oxidoreductases Acting on CH-NH Group Donors / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D009097:Multienzyme Complexes; D009842:Oligopeptides; D003300:Copper; D006899:Mixed Function Oxygenases; C035189:peptidylglycine monooxygenase; D000587:Oxidoreductases Acting on CH-NH Group Donors; D001205:Ascorbic Acid