A negative cooperativity between NADPH and adrenodoxin on binding to NADPH:adrenodoxin reductase |
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| Authors: | N K Cénas J A Marcinkeviciene J J Kulys S A Usanov |
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| Affiliation: | Institute of Biochemistry, Lithuanian Academy of Sciences, Vilnius, USSR. |
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| Abstract: | Adrenodoxin stimulated the oxidation of NADPH by 1,4-benzoquinone, catalyzed by NADPH:adrenodoxin reductase. It prevented the enzyme inhibition by NADPH and formed an additional pathway of benzoquinone reduction presumably via reduced adrenodoxin. In the presence of 100-400 microM NADP+, which increased the Km of NADPH, adrenodoxin acted as a partial competitive inhibitor for NADPH decreasing its TN/Km by a limiting factor of 3. Ki of adrenodoxin decreased on the NADP+ concentration decrease and was estimated to be about 10(-8) M in the absence of NADP+. |
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