Redox Properties of Bacillus subtilis Ferredoxin:NADP+ Oxidoreductase: Potentiometric Characteristics and Reactions with Pro-Oxidant Xenobiotics.
Int J Mol Sci
; 25(10)2024 May 14.
Article
de En
| MEDLINE
| ID: mdl-38791410
ABSTRACT
Bacillus subtilis ferredoxinNADP+ 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⢠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.
Mots clés
Texte intégral:
1
Collection:
01-internacional
Base de données:
MEDLINE
Sujet principal:
Oxydoréduction
/
Bacillus subtilis
/
Ferredoxine-NADP reductase
Langue:
En
Journal:
Int J Mol Sci
Année:
2024
Type de document:
Article
Pays d'affiliation:
Lituanie
Pays de publication:
Suisse