1.5.1.38: FMN reductase (NADPH)
This is an abbreviated version!
For detailed information about FMN reductase (NADPH), go to the full flat file.
Reaction
Synonyms
(NADPH)-dependent flavin mononucleotide reductase, (NADPH)-dependent FMN reductase, BC_1619, EC 1.5.1.29, EC 1.6.8.1, flavin reductase P, FMN reductase, FRP, More, NAD(P)H:FMN reductase, NADPH specific FMN reductase, NADPH-flavin oxidoreductase, NADPH-FMN oxidoreductase, NADPH:FMN oxidoreductase, NADPH:FMN reductase, SsuE, ssueE, ycbP, ydgI
ECTree
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Cofactor
Cofactor on EC 1.5.1.38 - FMN reductase (NADPH)
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2-thio-FMN
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binds to the cofactor site of the apoenzyme with an affinity similar to that for FMN binding. The holoenzyme reconstituted with 2-thioFMN is catalytically active in using either FMN or 2-thioFMN as a substrate
NADH
kcat/KM for NADPH is 335fold higher compared to kcat/KM for NADH
additional information
the enzyme does not contain any bound flavin cofactor
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FMN
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the apoenzyme binds one FMN per enzyme monomer with a dissociation constant of 0.2 mM at 23°C. The reconstituted holoenzyme is catalytically as active as the native enzyme. FMN binding results in 87% and 92% of quenching of protein and flavin fluorescence, respectively, indicating a conformational difference between the apoprotein and the holoenzyme. Neither riboflavin nor FAD shows any appreciable binding to the cofactor site of the apoenzyme but both flavins are active substrates for the FMN-containing holoenzyme
FMN
the enzyme is specific for FMN as cofactor. FMN is recognized and tightly bound by a network of 16 hydrogen bonds, while steric considerations prevent the binding of FAD. A flexible loop containing a Lys and an Arg could account for the NADPH specificity
NADPH
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the affinity of the NADPH-specific reductase for NADPH is 1000 times greater than for NADH