Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.6.5.2 (NQO1)
 6,196 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

NADPH-sulfite reductase flavoprotein (SiR-FP) was purified from a Salmonella typhimurium cysG strain that does not synthesize the hemoprotein component of the sulfite reductase holoenzyme. cysJ, which codes for SiR-FP, was cloned from S. typhimurium LT7 and Escherichia coli B, and both genes were sequenced. Physicochemical analyses and deduced amino acid sequences indicate that SiR-FP is an octamer of identical 66-kDa peptides and contains 4 FAD and 4 FMN per octamer. Potentiometric titrations of SiR holoenzyme, SiR-FP, and FMN-depleted SiR-FP yielded the following redox potentials for the prosthetic groups at pH 7.7: E'1 (FMNH./FMN) = -152 mV; E'2 (FMNH2/FMNH.) = -327 mV; E'3 (FADH./FAD) = -382 mV; E'4 (FADH2/FADH.) = -322 mV. Microcoulometric titration of SiR-FP at 25 degrees C yielded data which were in full agreement with these potentials. Spectroscopic and catalytic studies of native SiR-FP and of SiR-FP depleted of FMN support the following electron flow sequence: NADPH----FAD----FMN. FMN can then contribute electrons to the hemoprotein component of sulfite reductase, as well as to cytochrome c and various diaphorase acceptors. The FMN is postulated to cycle between the FMNH2 and FMNH. oxidation states during catalysis; in this sense SiR-FP shares a catalytic mechanism with NADPH-cytochrome P-450 oxidoreductase. SiR-FP domains involved in binding FMN, FAD, and NADPH are proposed from amino acid sequence homologies with Desulfovibrio vulgaris flavodoxin (Dubourdieu, M., and Fox, J.L. (1977) J. Biol. Chem. 252, 1453-1463) and spinach ferredoxin-NADP+ oxidoreductase (Karplus, P.A., Walsh, K.A., and Herriott, J. R. (1984) Biochemistry 23, 6576-6583). Comparison of the deduced amino acid sequences of SiR-FP and NADPH-cytochrome P-450 oxidoreductase (Porter, T. D., and Kasper, C.B. (1985) Proc. Natl. Acad. Sci. U. S.A. 82, 973-977) also showed identities that suggest these two proteins are descended from a common precursor, which contained binding regions for both FMN and FAD.
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PMID:Characterization of the flavoprotein moieties of NADPH-sulfite reductase from Salmonella typhimurium and Escherichia coli. Physicochemical and catalytic properties, amino acid sequence deduced from DNA sequence of cysJ, and comparison with NADPH-cytochrome P-450 reductase. 255 Apr 23

The NAD(P)H-flavin oxidoreductase gene from the bioluminescent bacterium, Vibrio fischeri ATCC 7744, was expressed in Escherichia coli, and the enzyme purified using Cibacron Blue 3G-A affinity column chromatography from crude extracts in a single step. The purified enzyme had a typical flavoprotein absorption spectrum and flavin mononucleotide (FMN) was identified as a prosthetic group, non-covalently bound in a molar ratio of 1:1. The enzyme catalyzed the electron transfer from NADH via FMNH2 to various other electron acceptors. Reduced flavin produced by flavin reductase participated non-enzymatically in the following reactions: H2O2-forming NADH oxidase-like, oxygen-insensitive nitroreductase-like, diaphorase (quinone reductase)-like and bacterial luciferase reactions.
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PMID:NAD(P)H-flavin oxidoreductase from the bioluminescent bacterium, Vibrio fischeri ATCC 7744, is a flavoprotein. 803 96

In the green alga Ankistrodesmus braunii, all the activities associated with the nitrate reductase complex (i.e., NAD(P)H-nitrate reductase, NAD(P)H-cytochrome c reductase and FMNH2-or MVH-nitrate reductase) are nutritionally repressed by ammonia or methylamine. Besides, ammonia or methylamine promote in vivo the reversible inactivation of nitrate reductase, but not of NAD(P)H-cytochrome c reductase. Subsequent removal of the inactivating agent from the medium causes reactivation of the inactive enzyme. Menadione has a striking stimulation on the in vivo reactivation of the inactive enzyme. The nitrate reductase activities, but not the diaphorase activity, can be inactivated in vitro by preincubating a partially purified enzyme preparation with NADH or NADPH. ADP, in the presence of Mg(2+), presents a cooperative effect with NADH in the in vitro inactivation of nitrate reductase. This effect appears to be maximum at a concentration of ADP equimolecular with that of NADH.
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PMID:Studies on the regulation of assimilatory nitrate reductase in Ankistrodesmus braunii. 2442 Jun 58

Chorismate synthase (Cs) is the last enzyme of the main trunk of shikimate pathway and catalyzes formation of chorismate, a major aromatic metabolite precursor. We have previously reported that Cs is highly conserved across different Plasmodium sp. Here we report that Cs from malaria parasites are bifunctional enzymes through expression and functional studies of two recombinant proteins rPfCs (Cs from P. falciparum) and rPvCs (Cs from P. vivax). We confirm bifunctional activity of both rPfCs and rPvCs based on their ability to catalyze formation of chorismate under aerobic conditions as well as their ability to catalyze generation of reduced flavin mononucleotide (FMN) as assessed through diaphorase assay.
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PMID:Chorismate synthase from malaria parasites is bifunctional enzyme. 3138 47