These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Lyophyllum cinerascens aminopeptidase: purification and enzymatic properties.
    Author: Abdus Sattar AK, Yoshimoto T, Tsuru D.
    Journal: Arch Biochem Biophys; 1989 Oct; 274(1):241-50. PubMed ID: 2774576.
    Abstract:
    An aminopeptidase (EC 3.4.11.1) was purified from the extract of Lyophyllum cinerascens by ammonium sulfate fractionation and sequential chromatographies on DEAE-Sephadex, Sephadex G-150, HPLC-phenyl-5PW, and HPLC-DEAE-5PW columns, with an activity recovery of 4.6% using Leu-beta-naphthylamide as a substrate. The enzyme was a tetrameric protein of molecular weight 150,000 and was found to be rich in histidine. It exhibited a pH optimum of 7.2 and stability between pH 5.7 and 7.7. The isoelectric point of the enzyme was 4.6. The enzyme catalyzed the hydrolysis of amino acid beta-naphthylamides, Phe greater than Leu greater than Met greater than Tyr greater than Ala greater than Glu, and the differences of the measured kcat's ranged over 2-3 orders of magnitude while many of the amino acid beta-naphthylamides were not hydrolyzed at all. Other interesting comparisons include two aliphatics, Ala vs Leu, and the aromatics, Tyr vs Phe, which show a 30-fold difference in the kcat/Km values. The enzyme also hydrolyzed Leu-Gly-Gly and the B chain of oxidized insulin to release N-terminal leucine and phenylalanine, respectively. The release of N-terminal Phe from the oxidized B chain is interesting in view of the fact that the penultimate residue is Val, an unfavorable amino acid in the beta-naphthylamide series. The enzyme seems to be a true aminopeptidase, requiring the free amino groups and hydrolyzing dipeptide and oligopeptide from the N-terminal end. The enzyme was resistant to the action of amastatin. Neither sulfhydryl reagents nor serine protease inhibitors affected the enzyme activity; however, the enzyme was inhibited weakly by EDTA and bestatin and strongly by diethyl pyrocarbonate.
    [Abstract] [Full Text] [Related] [New Search]