Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0016632 (Fox)
 1,461 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

This work examined the role of constitutional genetic variation at the glutathione S-transferase M1 (GSTM1) and NAD(P)H:quinone oxidoreductase 1 (NQO1) detoxification loci in breast cancer development. Methods included contrasting patterns of genetic variations at these loci between cases with breast cancer and healthy controls and assessing the association of genotypes with tumor characteristics. Participants were Caucasian women living in the Greater Philadelphia region, recruited from 1988 to 1994, with recently diagnosed women attending breast cancer clinics at Fox Chase Cancer Center (FCCC) and network affiliated hospitals as cases, and FCCC employees or women attending noncancer clinics as controls. The GSTM1 locus was determined for 402 cases and 238 controls, NQO1 for 346 cases and 235 controls. Results show that neither locus was associated with breast cancer occurrence, with the GSTM1 null genotype occurring at frequencies of 0.560 and 0.563 in cases and controls, respectively [odds ratio (OR) 0.98, 0.95 confidence interval (CI) 0.70-1.38] and the NQO1 wild-type allele at frequencies of 0.808 and 0.845, respectively (OR 0.77, 0.95 CI 0.55-1.06). The GSTM1 null genotype, however, was significantly overrepresented among larger (T3 and T4) primary tumors (OR 7.61, 0.95 CI 1.05-333) and with the occurrence of axillary lymph node metastases (OR 1.62, 0.95 CI 0.98-2.69). NQO1 results revealed that homozygotes for the wild type allele were more likely to have ductal carcinoma and poor histologic grade when compared with individuals carrying one or two mutated alleles (OR 3.50, 0.95 CI 1.41-9.0, and OR 2.26, 0.95 CI 1.18-4.35 for histology type and grade, respectively). We conclude that while these loci are not associated with breast cancer occurrence, the GSTM1 locus is likely associated with tumor progression. NQO1 results suggest that different quinones (possibly estrogenic quinone metabolites) might affect the histological development of breast tumors.
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PMID:Significance of genetic variation at the glutathione S-transferase M1 and NAD(P)H:quinone oxidoreductase 1 detoxification genes in breast cancer development. 1181 42