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    National Tsing Hua University Institutional Repository > 生命科學院  > 生命科學系 > 期刊論文 >  Kinetic Analysis of Zinc Ligand Mutants of Mammalian Protein Farnesyltransferase

    Please use this identifier to cite or link to this item: http://nthur.lib.nthu.edu.tw/dspace/handle/987654321/81424

    Title: Kinetic Analysis of Zinc Ligand Mutants of Mammalian Protein Farnesyltransferase
    Authors: Hua-Wen Fu;Lorena S. Beese;Patrick J. Casey
    教師: 傅化文
    Date: 1998
    Publisher: American Chemical Society
    Relation: Biochemistry, American Chemical Society, Volume 37, Issue 13, MAR 1998, Pages 4465-4472
    Abstract: Protein farnesyltransferase (FTase) is a zinc metalloenzyme that catalyzes the prenylation of
    several proteins that are important in cellular regulatory events. A specific residue of FTase, Cys299 in
    the â subunit previously identified as essential for zinc binding and catalysis, had been tentatively assigned
    as one of the zinc ligands. This assignment was subsequently confirmed in the X-ray structure of FTase,
    which also identified two additional residues, Asp297 and His362 in the â subunit, as the remaining
    protein-derived metal ligands. To more fully explore the role of zinc in the catalytic mechanism of FTase,
    site-directed mutagenesis was performed on these two zinc ligands. Although the abilities of all the
    mutants to bind the farnesyl diphosphate substrate were similar to that of the wild-type enzyme, all the
    mutants displayed markedly reduced enzymatic activities and zinc affinities. Steady-state and pre-steadystate kinetic analyses of the residual activities indicated that the rate-limiting step changed from product
    release in the wild-type enzyme to the chemical step of product formation for three of the mutant enzymes.
    Additionally, single-turnover experiments indicated that the greatest effect of alteration of zinc ligands
    for all the mutants was on the product formation step, this being reduced 10^3-10^5-fold in the mutant
    forms compared to the wild-type enzyme. These results confirm a critical involvement of the zinc in
    catalysis by FTase and support a model in which the metal ion is directly involved in the chemical step
    of the enzymatic reaction.
    Relation Link: http://pubs.acs.org/
    URI: http://nthur.lib.nthu.edu.tw/dspace/handle/987654321/81424
    Appears in Collections:[分子與細胞生物研究所] 期刊論文
    [生命科學系] 期刊論文

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