Catalyses the reduction of soluble flavins by reduced pyridine nucleotides. Highest activity with riboflavin. When NADH is used as acceptor, the enzyme can also utilize FMN and FAD as substrates, with lower activity than riboflavin. When NADPH is used as acceptor, the enzyme has a very low activity with FMN and no activity with FAD .
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SYSTEMATIC NAME
IUBMB Comments
riboflavin:NAD(P)+ oxidoreductase
Catalyses the reduction of soluble flavins by reduced pyridine nucleotides. Highest activity with riboflavin. When NADH is used as acceptor, the enzyme can also utilize FMN and FAD as substrates, with lower activity than riboflavin. When NADPH is used as acceptor, the enzyme has a very low activity with FMN and no activity with FAD [1].
interactions for flavin substrates are provided by a hydrophobic isoalloxazine binding site that also contains a serine and a threonine, which form hydrogen bonds to the isoalloxazine of bound riboflavin in a substrate complex
enzyme Fre uses the FMN MsrQ cofactor as a substrate to catalyze the electron transfer from cytosolic NADH to the heme. Formation of a specific complex between MsrQ and Fre could favor this unprecedented mechanism, which most likely involves transfer of the reduced FMN cofactor from the Fre active site to MsrQ. Fre forms a specific complex with wild-type MsrQ and the MsrQ H151A mutant. The H151A mutation has no significant quantitative effects on the MsrQ/Fre interaction. Since the MsrQ H151A mutation specifically induces the loss of the FMN cofactor, these data suggest that the flavin cofactor is not involved in the formation of the MsrQ/Fre complex
enzyme Fre uses the FMN MsrQ cofactor as a substrate to catalyze the electron transfer from cytosolic NADH to the heme. Formation of a specific complex between MsrQ and Fre could favor this unprecedented mechanism, which most likely involves transfer of the reduced FMN cofactor from the Fre active site to MsrQ. Fre forms a specific complex with wild-type MsrQ and the MsrQ H151A mutant. The H151A mutation has no significant quantitative effects on the MsrQ/Fre interaction. Since the MsrQ H151A mutation specifically induces the loss of the FMN cofactor, these data suggest that the flavin cofactor is not involved in the formation of the MsrQ/Fre complex
the purified refolded enzyme does not contain FMN, unlike the same enzyme expressed as a soluble protein. After the addition of FMN to the protein solution, the refolded enzyme shows a higher activity than the enzyme expressed as the soluble protein
in Escherichia coli NAD(P)H:flavin oxidoreductase is part of a multienzyme system that reduces the Fe(III) center of ribonucleotide reductase to Fe(II) and thereby sets the stage for the generation by dioxygen of a free tyrosyl radical required for enzyme activity
the flavin reductase Fre in Escherichia coli reduces the cofactor FMN of MsrQ, that is part of MsrPQ, a distinct type of methionine sulfoxide reductase (Msr) system found in bacteria. It is specifically involved in the repair of periplasmic methionine residues that are oxidized by hypochlorous acid. MsrP is a periplasmic molybdoenzyme that carries out the Msr activity, whereas MsrQ, an integral membrane-bound hemoprotein, acts as the physiological partner of MsrP to provide electrons for catalysis. MsrQ holds a flavin mononucleotide (FMN) cofactor that occupies the site where a second heme binds in other members of the FDR superfamily on the cytosolic side of the membrane. EPR spectroscopy indicates that the FMN cofactor can accommodate a radical semiquinone species. The cytosolic flavin reductase Fre has previously been shown to reduce the MsrQ heme. Fre uses the FMN MsrQ cofactor as a substrate to catalyze the electron transfer from cytosolic NADH to the heme. Formation of a specific complex between MsrQ and Fre favors this unprecedented mechanism, which most likely involves transfer of the reduced FMN cofactor from the Fre active site to MsrQ
improvement of the intracellular environment for enhancing L-arginine production of Corynebacterium glutamicum by inactivation of H2O2-forming flavin reductases and optimization of ATP supply. Construction of mutants of gene frd1, strain 5-5(frd1) and deletion strains 5-5DELTAfrd1 and 5-5DELTAfrd12. The extracellular H2O2 concentrations of mutants 5-5DELTAfrd1 and 5-5DELTAfrd12 are lower than that of the wild-type strain SYPA5-5, and the extracellular H2O2 concentrations of mutant 5-5(frd1) is increased compared to the wild-type. Flavin reductase activities in frd1 and frd2 overexpression and deletion strains with NADH and FAD, overview
improvement of the intracellular environment for enhancing L-arginine production of Corynebacterium glutamicum by inactivation of H2O2-forming flavin reductases and optimization of ATP supply. Construction of mutants of gene frd1, strain 5-5(frd1) and deletion strains 5-5DELTAfrd1 and 5-5DELTAfrd12. The extracellular H2O2 concentrations of mutants 5-5DELTAfrd1 and 5-5DELTAfrd12 are lower than that of the wild-type strain SYPA5-5, and the extracellular H2O2 concentrations of mutant 5-5(frd1) is increased compared to the wild-type. Flavin reductase activities in frd1 and frd2 overexpression and deletion strains with NADH and FAD, overview
gene frd1, DNA and amino acid sequence determination and analysis, sequence comparisons, recombinant overexpression of N-terminally His-tagged enzyme in Escherichia coli strain BL21(DE3)
Man, Z.; Rao, Z.; Xu, M.; Guo, J.; Yang, T.; Zhang, X.; Xu, Z.
Improvement of the intracellular environment for enhancing L-arginine production of Corynebacterium glutamicum by inactivation of H2O2-forming flavin reductases and optimization of ATP supply