• Title/Summary/Keyword: pyridine nucleotide

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Relationship of the Redox State of Pyridine Nucleotides and Quinone Pool with Spectral Complex Formation in Rhodobacter sphaeroides 2.4.1 (Rhodobacter sphaeroides 2.4.1 내의 pyridine nucleotide와 quinone pool의 redox 상태와 광합성기구의 합성과의 상관관계)

  • Ko, In-Jeong;Oh, Jeong-Il
    • Journal of Life Science
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    • v.19 no.7
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    • pp.852-858
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    • 2009

  • The homeostasis of the pyridine nucleotide pool [NAD(P)H and NAD(P)$^+$] is maintained in Rhodobacter sphaeroides mutant strains defective in the cytochrome bci complex or the cytochrome c oxidases in terms of its concentration and redox state. Aerobic derepression of the puf operon, which is under the control of the PrrBA two-component system, in the CBB3 mutant strain of R. sphaeroides was shown to be not the result of changes in the redox state of the pyridine nucleotides and the ubiquinone/ubiquinol pool. Using the bc$_1$ complex knock-out mutant strain of R. sphaeroides, we clearly demonstrated that the inhibitory effect of cbb$_3$, oxidase on spectral complex formation is not caused indirectly by the redox change of the ubiquinone/ubiquinol pool.

  • https://doi.org/10.5352/JLS.2009.19.7.852 인용 PDF KSCI

Characterization of the ${\cdot}O_{2}^{-}$-Formation by Pyridine Nucleotide in Rat Hepatocytes

  • Kim, Ki-Sung
    • BMB Reports
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    • v.28 no.6
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    • pp.533-537
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    • 1995

  • The detection with lucigenin under physiological conditions is selective for ${\cdot} O_{2}^{-}$, for it can be accepted that lucigenin indicates actual intramembranal $\cdot O_{2}^{-}- formation$. Lucigenin chemiluminescence (CL) was elicited from the plasma membrane (PM) only by addition of reduced pyridine nucleotide. NADPH was preferred to NADH in PM and hepatocytes. This specificity was masked by $NAD(P)^+$ inhibition. The half maximum rate of CL increase was obtained with 1.5 ${\mu}m$ NADH or 55 ${\mu}m$ NADPH in hepatocytes and 6 ${\mu}m$ NADH or 30 ${\mu}m$ NADPH in plasma membranes. Measurement of these NADPH values required the presence of a NADPH-regenerating system. With NADPH the maximal rate obtained was 10 fold higher than with NADH. NADPH and NADH could produce CL when having access from either side of the membrane. They seemed to react with the identical acceptor because NADH-induced CL was also inhibited by $NADP^+$. The characteristics of ${\cdot}O_{2}^{-}-formation$ produced by pyridine nucleotide will be discussed.

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Activity of Human Dihydrolipoamide Dehydrogenase Is Largely Reduced by Mutation at Isoleucine-51 to Alanine

  • Kim, Hak-Jung
    • BMB Reports
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    • v.39 no.2
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    • pp.223-227
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    • 2006

  • Dihydrolipoamide dehydrogenase (E3) belongs to the pyridine nucleotide-disulfide oxidoreductase family including glutathione reductase and thioredoxin reductase. It catalyzes the reoxidation of dihydrolipoyl moiety of the acyltransferase components of three $\alpha$-keto acid dehydrogenase complexes and of the hydrogen-carrier protein of the glycine cleavage system. Isoleucine-51 of human E3, located near the active disulfide center Cys residues, is highly conserved in most E3s from several sources. To examine the importance of this highly conserved Ile-51 in human E3 function, it was substituted with Ala using site-directed mutagenesis. The mutant was expressed in Escherichia coli and highly purified using an affinity column. Its E3 activity was decreased about 100-fold, indicating that the conservation of the Ile-51 residue in human E3 was very important to the efficient catalytic function of the enzyme. Its altered spectroscopic properties implied that conformational changes could occur in the mutant.

  • https://doi.org/10.5483/BMBRep.2006.39.2.223 인용 PDF

Activity of Human Dihydrolipoamide Dehydrogenase Is Reduced by Mutation at Threonine-44 of FAD-binding Region to Valine

  • Kim, Hak-Jung
    • BMB Reports
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    • v.35 no.4
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    • pp.437-441
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    • 2002

  • Dihydrolipoamide dehydrogenase (E3) is a member of the pyridine nucleotide-disulfide oxidoreductase family. Thr residues are highly conserved. They are at the active site disulfide-bond regions of most E3s and other oxidoreductases,. The crystal structure of Azotobacter vinelandii E3 suggests that the hydroxyl group of Thr that are involved in the FAD binding interact with the adenosine phosphate of FAD. However, several prokaryotic E3s have Val instead of Thr. To investigate the meaning and importance of the Thr conservation in many E3s, the corresponding residue, Thr-44, in human E3 was substituted to Val by site-directed mutagenesis. The mutant’s E3 activity showed about a 2.2-fold decrease. Its UV-visible and fluorescence spectra indicated that the mutant might have a slightly different microenvironment at the FAD-binding region.

  • https://doi.org/10.5483/BMBRep.2002.35.4.437 인용 PDF