Purification and properties of an aminopeptidase from Alaska pollack, Theragra chalcogramma, roe.
An aminopeptidase was isolated from a soluble fraction of Alaska pollack roe in the presence of 2-mercaptoethanol by fractionation with ammonium sulfate and column chromatography on DEAE-cellulose, hydroxyapatite, and Sephadex G-200. The molecular weight of the enzyme was estimated to be 125,000 and 105,000 by gel filtration and sodium dodecyl sulfate-polyacrylamide gel electrophoresis, respectively. The pH optimum and temperature optimum were 7.2 and 35 degrees C, respectively. The purified enzyme hydrolyzed various alpha-aminoacyl beta-naphthylamides and cleaved L-Ala-beta-naphthylamide most rapidly. Both a sulfhydryl group and a divalent metal ion are essential for activity; however, the enzyme was inhibited when incubated with divalent metal ions. Puromycin, chelating agents, and thiol reagents were effective inhibitors. The enzyme was also inhibited by L-amino acids, in particular glutamic acid. Thus, the Alaska pollack roe aminopeptidase resembles soluble alanyl aminopeptidase [EC 3.4.11.14].
Laboratory of Marine Biochemistry, Faculty of Agriculture, University of Tokyo.
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D000596:Amino Acids / Q000032:analysis; D000626:Aminopeptidases / Q000032:analysis / Q000037:antagonists & inhibitors / Q000302:isolation & purification*; D000818:Animals; D002413:Cations, Divalent / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D005399:Fishes / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D008970:Molecular Weight; D010063:Ovum / Q000201:enzymology; D013379:Substrate Specificity; D013438:Sulfhydryl Compounds / Q000494:pharmacology; D013696:Temperature
D000596:Amino Acids; D002413:Cations, Divalent; D013438:Sulfhydryl Compounds; D000626:Aminopeptidases