Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:Q8NEX9 (reductase)
 26,410 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Nitrogenase proteins were isolated from cultures of the photosynthetic bacterium Rhodopseudomonas capsulata grown on a limiting amount of ammonia. Under these conditions, the nitrogenase N2ase A was active in vivo, and nitrogenase activity in vitro was not dependent upon manganese and the activating factor. The nitrogenase proteins were also isolated from nitrogen-limited cultures in which the in vivo nitrogenase activity had been stopped by an ammonia shock. This nitrogenase activity, N2ase R, showed an in vitro requirement for manganese and the activating factor for maximal activity. The Mo-Fe protein (dinitrogenase) was composed of two dissimilar subunits with molecular weights of 55,000 and 59,500; the Fe protein (dinitrogenase reductase), from either type of culture, was composed of a single subunit (molecular weight), 33,500). The metal and acid labile sulfur contents of both nitrogenase proteins were similar to those found for previously isolated nitrogenases. The Fe proteins from both N2ase A and N2ase R contained phosphate and ribose, 2 mol of each per mol of N2ase R Fe protein and about 1 mol of each per mol of N2ase A Fe protein. The greatest difference between the two types of Fe protein was that the N2ase R Fe protein contained about 1 mol per mol of an adenine-like molecule, whereas the N2ase A Fe protein content of this compound was insignificant. These results are compared with various models previously presented for the short-term regulation of nitrogenase activity in the photosynthetic bacteria.
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PMID:Nitrogenase from the photosynthetic bacterium Rhodopseudomonas capsulata: purification and molecular properties. 679 95

Six mutant strains (301, 102, 203, 104, 305, and 307) affected in their nitrate assimilation capability and their corresponding parental wild-type strains (6145c and 21gr) from Chlamydomonas reinhardii have been studied on different nitrogen sources with respect to NAD(P)H-nitrate reductase and its associated activities (NAD(P)H-cytochrome c reductase and reduced benzyl viologen-nitrate reductase) and to nitrite reductase activity. The mutant strains lack NAD(P)H-nitrate reductase activity in all the nitrogen sources. Mutants 301, 102, 104, and 307 have only NAD(P)H-cytochrome c reductase activity whereas mutant 305 solely has reduced benzyl viologen-nitrate reductase activity. Both activities are repressible by ammonia but, in contrast to the nitrate reductase complex of wild-type strains, require neither nitrate nor nitrite for their induction. Moreover, the enzyme from mutant 305 is always obtained in active form whereas nitrate reductase from wild-types needs to be reactivated previously with ferricyanide to be fully detected. Wild-type strains and mutants 301, 102, 104, and 307, when properly induced, exhibit an NAD(P)H-cytochrome c reductase distinguishable electrophoretically from constitutive diaphorases as a rapidly migrating band. Nitrite reductase from wild-type and mutant strains is also repressible by ammonia and does not require nitrate or nitrite for its synthesis. These facts are explained in terms of a regulation of nitrate reductase synthesis by the enzyme itself.
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PMID:Regulation of the nitrate-reducing system enzymes in wild-type and mutant strains of Chlamydomonas reinhardii. 681 63

Nitrogen-15 nuclear magnetic resonance (15N NMR) spectroscopy at 30.4 MHz was employed to determine the interaction of the substrate nitrite (97.2% enriched) with bacterial nitrite reductase, denoted cytochrome cd1, from Pseudomonas aeruginosa. The addition of ferric enzyme to nitrite did not alter the chemical shift of the bulk nitrite resonance, nor was it possible to observe a new resonance from a hypothetical bound form. However, the spin-lattice relaxation time (T1) was lowered from 13.2 to 2.7 s, and the spin-spin relaxation time (T2) was halved. Values of T1 were measured by progressive saturation and values of T2 by line widths. Control experiments involving ferric cytochrome c and metmyoglobin demonstrated that the perturbations did not arise from the bulk paramagnetic properties of the protein solutions. Variable enzyme/substrate ratios were measured to assess the strength of interaction. The most reasonable model consistent with the data proposes a weak association between nitrite and ferric reductase with a value of 1.3 M-1 for the association constant.
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PMID:Nitrogen-15 nuclear magnetic resonance investigation of nitrite reductase-substrate interaction. 681 79

Complementation tests were performed with various nif mutations for delineating the nif genes. The nif-/nif- heterogenotes were constructed by transferring nif plasmid mutant PRD-nif- from E. coli Jc5466 to various Klebsiella pneumoniae nif- recipients. In addition to those nif genes previously reported elsewhere, a new essential gene for nitrogen fixation, nifC was identified. According to the P1-transduction and three factor reciprocal crosses, nifC was tentatively mapped between nifH and nifJ in the chromsome. The order of nif genes obtained was hisD, nifQ, nifB, nifA, nifL, nifF nifM, nifV, nifS, nifU, nifN, nifE, nifK, nifD, nifH, nifC and nifJ. The examination of the biochemical phenotypes of the nif genes suggests that nifC may be concerned with the synthesis or activation of the iron molybdenum cofactor nitrogenase, nifH, besides coding for the structure of nitrogen reductase may also exert a function on the synthesis of nitrogenase, and nifJ presumably is required to turn on the expression of nifK (D), nifH or nifF.
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PMID:Complementation analysis and characterization of the nitrogen fixation genes, nifH, nifC and nifJ in Klebsiella pneumoniae. 698 61

Two hisD-unlinked genes NifC5 and NifC7 are mapped in the chromosome of K. pneumoniae. The sequence of NifC5 and NifC7 is suggested as NifC5--gltB--NifC7--argG. The P1 infected E. coli lysate can transduce the mutant C-7 to be Nif+ transductant, yet fails to transduce the hisD-linked nif mutants to be Nif+ ones. This indicates that the gene encoding C-7 is not the structural gene of nitrogen fixation and is present in E. coli. It is actually a gene specifying the glutamate synthetase. SDS electrophoresis shows the marked low content of nitrogen reductase and immunoelectrophoretic test reveals the reduced amount of both nitrogenase and nitrogen reductase in the mutant cells.
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PMID:Mapping and characterization of the hisD-unlinked nif mutants in Klebsiella pneumoniae. 698 63

Pretreatment with cycloheximide or emetine provided significant protection against pulmonary edema in rats exposed to ozone or nitrogen dioxide. Other inhibitors of protein-synthesis, actinomycin D or puromycin, failed to show such effects. Possible actions of these agents as well as the doses and times that afforded the significant protection were investigated. These agents, by themselves, did not alter the water content of the lungs. In vitro study revealed that both cycloheximide and emetine hardly acted as scavengers of oxidant. Pretreatment with either agent was associated with a significant increase in the activity of glucose 6-phosphate dehydrogenase of the lungs, but the increase did not necessarily coincide with the protection. Activity levels of non-protein SH, glutathione-peroxidase and -reductase in the lungs of rats treated with either agent were scarcely altered. The effect of these agents administered in vivo or in vitro on the in vitro lipid peroxidation by air was also investigated. Other possible mechanisms of these agents responsible for the protective effect against pulmonary edema induced by oxidants were also discussed.
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PMID:Protection with cycloheximide or emetine against pulmonary edema induced by ozone or nitrogen dioxide. 713 93

Proliferation of tubular epithelial cells is a major element leading to cyst formation in Han:SPRD rats with autosomal dominant polycystic kidney disease (PKD). ras proteins are important in the control of renal cell proliferation, and ras gene expression is increased in PKD. Farnesyl pyrophosphate, an intermediate in the conversion of acetyl-CoA to cholesterol, is required for the activation of ras guanosine triphosphate (GTP)-binding proteins that are important in the execution of several cellular functions, including cell proliferation. 3-Hydroxy-3-methyl-glutaryl coenzyme A reductase inhibitors, such as lovastatin, reduce farnesyl production in responsive cells and thereby have potential for ameliorating the accelerated epithelial cell proliferation of PKD. We administered lovastatin to heterozygous (Cy/+) Han:SPRD rats (4 mg/kg/d subcutaneously) from age 4 to 10 weeks, a period of rapid cystic disease progression in these animals. Untreated male Cy/+ rats developed larger cystic kidneys and had more severe renal functional impairment than females, as reported previously. In males, lovastatin significantly decreased cystic kidney size (referenced to body weight), the volume density of cysts, and the serum urea nitrogen level 14.5%, 24.4%, and 25.6/%, respectively. The corresponding changes in females were insignificant, and lovastatin had no effect on kidney weight or serum urea nitrogen in homozygous (+/+) normal male animals. On the basis of these results we conclude that lovastatin diminishes the severity of PKD in heterozygous male Han:SPRD rats.
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PMID:Effect of lovastatin on the development of polycystic kidney disease in the Han:SPRD rat. 764 59

The nir and nor genes, which encode nitrite and nitric oxide reductase, lie close together on the DNA of Paracoccus denitrificans. We here identify an adjacent gene, nnr, which is involved in the expression of nir and nor under anaerobic conditions. The corresponding protein of 224 amino acids is homologous with the family of FNR proteins, although it lacks the N-terminal cysteines. A mutation in the nnr gene had a negative effect on the expression of nitrite and nitric oxide reductase. Synthesis of membrane bound nitrate reductase, of nitrous oxide reductase, and of the cbb3-type cytochrome c oxidase were not affected by mutation of this gene. These results suggest that denitrification in P. denitrificans may be governed by a signal transduction network that is similar to that involved in oxygen regulation of nitrogen metabolism in other organisms.
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PMID:Nitrite and nitric oxide reduction in Paracoccus denitrificans is under the control of NNR, a regulatory protein that belongs to the FNR family of transcriptional activators. 787 19

The products of the nifN and nifE genes of Azotobacter vinelandii function as a 200-kDa alpha 2 beta 2 tetramer (NIFNE) in the synthesis of the iron-molybdenum cofactor (FeMo-co) of nitrogenase, the enzyme system required for biological nitrogen fixation. NIFNE was purified using a modification of the published protocol. Immunoblot analysis of anoxic native gels indicated that distinct forms of NIFNE accumulate in strains deficient in either NIFB (delta nifB::kan delta nifDK) or NIFH (delta nifHDK). During the purification of NIFNE from the delta nifHDK mutant, its mobility in these gels changed, becoming similar to that of NIFNE from the delta nifB::kan delta nifDK mutant. While NIFB activity initially co-purified with the NIFNE activity from the delta nifHDK mutant, further purification of NIFNE activity resulted in the loss of the co-purifying NIFB activity; this loss correlated with the change in NIFNE mobility on native gels. These results suggest that the form of NIFNE accumulated in the delta nifHDK mutant is associated with NIFB activity in crude extract but loses this association during NIFNE purification. Addition of the purified metabolic product of NIFB, termed NifB-co, to either NIFNE purified from the delta nifHDK strain or to the NIFNE in crude extract of the delta nifB::kan delta nifDK strain caused a change in the mobility of NIFNE on anoxic native gels to that of the form accumulated in a delta nifHDK mutant. These results support a model where both NifB-co and dinitrogenase reductase participate in FeMo-co synthesis through NIFNE, which serves as a scaffold for this process.
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PMID:Characteristics of NIFNE in Azotobacter vinelandii strains. Implications for the synthesis of the iron-molybdenum cofactor of dinitrogenase. 787 9

The aim of this study was to define the long-term stability of metabolizing enzymes in activating preparations for short-term genotoxicity bioassays under various storage conditions. Expressions of cytochrome P450 content, NADPH-cytochrome (P450) c-reductase activity, and of the several monooxygenases, such as aminopyrine N-demethylase (class IIIA P450), p-nitroanisole O-demethylase (mixed), dinemorphan N-demethylase (IIB1), ethoxyresorufin O-deethylase (IA1), ethoxycoumarin O-deethylase (mixed), and pentoxyresorufin O-dealkylase (IIB1), were examined in S9 fractions derived from Na-phenobarbital (PB) plus beta-naphthoflavone (beta-NF) induced male and female mice, stored at -80 degrees C, or lyophilized and stored at -20 degrees C. Lipid peroxidation was also determined. Cytochrome P450 and the associated activities were decreased by 30-82% within 9 months of storage. The pattern and degree of relative stabilities were different for the various isoforms. The IA1-like activity, for example, was much more stable (approximately 49% loss) than IIB1-like activities (up to 82% loss). In general, lyophilized enzymes were less stable than directly frozen preparations. In addition, immediately after freeze-drying (lyophilization), a marked decrease in activity of up to 35% was observed. On the contrary, demethylation of aminopyrine and p-nitroanisole remains almost constant over 6 months storage at -196 degrees C. The results obtained indicate that either fresh, daily made S9 fractions or, alternatively, fractions stored in liquid nitrogen (up to 6 months) are recommended for mutagenesis studies.
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PMID:Stability of microsomal monooxygenases in murine liver S9 fractions derived from phenobarbital and beta-naphthoflavone induced animals under various long-term conditions of storage. 791 Apr 16


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