Kinetic and thermodynamic properties of the folding and assembly of formate dehydrogenase

Authors

  • Emel B. Ordu,

    1. Istanbul Technical University, Faculty of Science and Letters, Department of Molecular Biology and Genetics, Istanbul, Turkey
    2. Istanbul Technical University, Molecular Biology-Biotechnology and Genetics Research Centre, 34469 Istanbul, Turkey
    3. Yildiz Technical University, Faculty of Science and Letters, Department of Biology, Davutpasa, 34220 Esenler, Istanbul, Turkey
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  • Gus Cameron,

    1. University of Bristol, Department of Biochemistry, Bristol BS8 1TD, Avon, England
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  • Anthony R. Clarke,

    1. University of Bristol, Department of Biochemistry, Bristol BS8 1TD, Avon, England
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  • Nevin Gül Karagüler

    Corresponding author
    1. Istanbul Technical University, Faculty of Science and Letters, Department of Molecular Biology and Genetics, Istanbul, Turkey
    2. Istanbul Technical University, Molecular Biology-Biotechnology and Genetics Research Centre, 34469 Istanbul, Turkey
    • Corresponding author. Address: Istanbul Technical University, Faculty of Science and Letters, Department of Molecular Biology and Genetics, 34469 Istanbul, Turkey. Fax: +90 212 2856386.

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Abstract

The folding mechanism and stability of dimeric formate dehydrogenase from Candida methylica was analysed by exposure to denaturing agents and to heat. Equilibrium denaturation data yielded a dissociation constant of about 10−13 M for assembly of the protein from unfolded chains and the kinetics of refolding and unfolding revealed that the overall process comprises two steps. In the first step a marginally stable folded monomeric state is formed at a rate (k 1) of about 2 × 10−3 s−1 (by deduction k −1 is about10−4 s−1) and assembles into the active dimeric state with a bimolecular rate constant (k 2) of about 2 × 104 M−1 s−1. The rate of dissociation of the dimeric state in physiological conditions is extremely slow (k −2 ∼ 3 × 10−7 s−1).

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