title: Purification and properties of an aminopeptidase from the mid-gut gland of scallop (Patinopecten yessoensis).
abstract: An aminopeptidase was isolated from the mid-gut gland of Patinopecten yessoensis. The enzyme was purified from an acetone-dried preparation by extracting, ammonium sulfate precipitation, Hi-Load Q column chromatography, isoelectric focusing, and POROS HP2 and HQ column chromatography. The molecular weight of the enzyme was estimated to be 61 kDa by SDS-polyacrylamide gel electrophoresis and 59 kDa by gel permeation chromatography. The isoelectric point of the enzyme was 5.2 and the optimum pH was 7.0 toward leucine p-nitroanilide (Leu-pNA). The enzyme was inhibited by o-phenanthroline. The activity of the enzyme treated with o-phenanthroline was completely recovered by adding excess Zn(2+). Relative hydrolysis rates of amino acid-pNAs and amino acid-4-methylcoumaryl-7-amides (amino acid-MCAs) indicated that the enzyme preferred substrates having Ala or Met as an amino acid residue. The enzyme had a K(m) of 32.2 microM and k(cat) of 29.5 s(-1) with Ala-pNA and a K(m) of 11.1 microM and k(cat) of 9.49 s(-1) with Ala-MCA. The enzyme sequentially liberated amino acids from the amino-termini of Ala-Phe-Tyr-Glu.
authors.affiliation: Graduate School of Environmental Science, Aomori University, Kobata, Aomori 030-0943, Japan. umetsu@aomori-u.ac.jp
authors.forename: Hironori
authors.initials: H
authors.lastname: Umetsu
authors.forename: Mito
authors.initials: M
authors.lastname: Arai
authors.forename: Toshinori
authors.initials: T
authors.lastname: Ota
authors.forename: Ryohei
authors.initials: R
authors.lastname: Kudo
authors.forename: Hitomi
authors.initials: H
authors.lastname: Sugiura
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Ishiyama
authors.forename: Kazuo
authors.initials: K
authors.lastname: Sasaki
mesh_terms: D000626:Aminopeptidases / Q000302:isolation & purification* / Q000378:metabolism*; D000818:Animals; D004591:Electrophoresis, Polyacrylamide Gel; D004795:Enzyme Stability; D005753:Gastric Mucosa / Q000201:enzymology*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008974:Mollusca / Q000201:enzymology*; D013379:Substrate Specificity
chemical_list: D000626:Aminopeptidases