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Redox Properties of Bacillus subtilis Ferredoxin:NADP + Oxidoreductase: Potentiometric Characteristics and Reactions with Pro-Oxidant Xenobiotics.
- Source :
- International Journal of Molecular Sciences; May2024, Vol. 25 Issue 10, p5373, 16p
- Publication Year :
- 2024
-
Abstract
- Bacillus subtilis ferredoxin:NADP<superscript>+</superscript> oxidoreductase (BsFNR) is a thioredoxin reductase-type FNR whose redox properties and reactivity with nonphysiological electron acceptors have been scarcely characterized. On the basis of redox reactions with 3-acetylpyridine adenine dinucleotide phosphate, the two-electron reduction midpoint potential of the flavin adenine dinucleotide (FAD) cofactor was estimated to be −0.240 V. Photoreduction using 5-deazaflavin mononucleotide (5-deazaFMN) as a photosensitizer revealed that the difference in the redox potentials between the first and second single-electron transfer steps was 0.024 V. We examined the mechanisms of the reduction of several different groups of non-physiological electron acceptors catalyzed by BsFNR. The reactivity of quinones and aromatic N-oxides toward BsFNR increased when increasing their single-electron reduction midpoint redox potentials. The reactivity of nitroaromatic compounds was lower due to their lower electron self-exchange rate, but it exhibited the same trend. A mixed single- and two-electron reduction reaction was characteristic of quinones, whereas reactions involving nitroaromatics proceeded exclusively via the one-electron reduction reaction. The oxidation of FADH<superscript>•</superscript> to FAD is the rate-limiting step during the oxidation of fully reduced FAD. The calculated electron transfer distances in the reaction with nitroaromatics were close to those of other FNRs including the plant-type enzymes, thus demonstrating their similar active site accessibility to low-molecular-weight oxidants despite the fundamental differences in their structures. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 16616596
- Volume :
- 25
- Issue :
- 10
- Database :
- Complementary Index
- Journal :
- International Journal of Molecular Sciences
- Publication Type :
- Academic Journal
- Accession number :
- 177488982
- Full Text :
- https://doi.org/10.3390/ijms25105373