Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.7.1.4 (nitrite reductase)
 1,847 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Enzymes and proteins: AO, amine oxidase; and as proposed in reference 3, BSAO, bovine serum AO; SSAO, swine serum AO; SKDAO, swine kidney AO; PSAO, pea seedling AO; APAO, arthrobacter P1AO; MADH, methylamine dehydrogenase; AAO, ascorbic acid oxidase; alpha-AE, alpha-amidating enzyme; Az, azurin; COX, cytochrome c oxidase; CP, ceruloplasmin; DBH, dopamine beta-hydroxylase; GO, galactose oxidase; Hc, hemocyanin; MT, metallotheonein; NIR, nitrite reductase; SOD, superoxide dismutase. Cofactors: Dopa, 3,4 dihydroxyphenylalanine; Topa, 3,4,6 trihydroxyphenyl-alanine; PLP, pyridoxal-phosphate; PQQ, pyrroloquinolinequinone. Reagents: DDC, diethyldithiocarbamate; DMG, diaminoguanidine; DMSA, dimercaptosuccinic acid; NTA, nitrilotriacetic acid. Technique-related: XANES, x-ray absorption near edge spectroscopy; EXAFS, extended x-ray absorption fine structure; ENDOR, electron-nuclear double resonance; ESEEM, electron spin echo envelope modulation; CD, circular dichroism; MCD, magnetic circular dichroism; NMRD, nuclear magnetic resonance dispersion; nqi, nuclear quadrupole interaction; DSC, differential scanning calorimetry.
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PMID:Copper in biological systems. A report from the 6th Manziana Conference, September 23-27, 1990. 175 86

The nature of the heme centers in the hexa-heme dissimilatory nitrite reductase from the bacterium Wolinella succinogenes has been investigated with EPR and magnetic circular dichroism spectroscopy. The EPR spectrum of the ferric enzyme is complex showing, in addition to magnetically isolated low-spin ferric hemes with g values of 2.93, 2.3 and 1.48, two sets of signals at g = 10.3, 3.7 and 4.8, 3.21, which we assign to two pairs of exchange coupled hemes. The MCD spectra show that the isolated hemes are bis-histidine coordinated and that there is one high-spin ferric heme. The exchange coupling is lost on treatment with SDS.
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PMID:Electron paramagnetic resonance and magnetic circular dichroism studies of a hexa-heme nitrite reductase from Wolinella succinogenes. 303 99

Paracoccus pantotrophus cytochrome cd(1) is a physiological nitrite reductase and an in vitro hydroxylamine reductase. The oxidised "as isolated" form of the enzyme has bis-histidinyl coordinated c-heme and upon reduction its coordination changes to histidine/methionine. Following treatment of reduced enzyme with hydroxylamine, a novel, oxidised, conformer of the enzyme is obtained. We have devised protocols for freeze-quench near-ir-MCD spectroscopy that have allowed us to establish unequivocally the c-heme coordination of this species as His/Met. Thus it is shown that the catalytically competent, hydroxylamine reoxidised, form of P. pantotrophus cytochrome cd(1) has different axial ligands to the c-heme than "as isolated" enzyme.
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PMID:A novel conformer of oxidized Paracoccus pantotrophus cytochrome cd(1) observed by freeze-quench NIR-MCD spectroscopy. 1111 44

A combination of spectroscopic methods and density functional calculations has been used to describe the electronic structure of the axial mutant (Met182Thr) of Rhodobacter sphaeroides nitrite reductase in which the axial methionine has been changed to a threonine. This mutation results in a dramatic change in the geometric and electronic structure of the copper site. The electronic absorption data imply that the type 1 site in the mutant is like a typical blue copper site in contrast to the wild-type site, which is green. Similar ligand field strength in the mutant and the wild type (from MCD spectra) explains the similar EPR parameters for very different electronic structures. Resonance Raman shows that the Cu-S(Cys) bond is stronger in the mutant relative to the wild type. From a combination of absorption, CD, MCD, and EPR data, the loss of the strong axial thioether (present in the wild-type site) results in an increase of the equatorial thiolate-Cu interaction and the site becomes less tetragonal. Spectroscopically calibrated density functional calculations were used to provide additional insight into the role of the axial ligand. The calculations reproduce well the experimental ground-state bonding and the changes in going from a green to a blue site along this coupled distortion coordinate. Geometry optimizations at the weak and strong axial ligand limits show that the bonding of the axial thioether is the key factor in determining the structure of the ground state. A comparison of plastocyanin (blue), wild-type nitrite reductase (green), and the Met182Thr mutant (blue) sites enables evaluation of the role of the axial ligand in the geometric and electronic structure of type 1 copper sites, which can affect the electron-transfer properties of these sites.
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PMID:Spectroscopic studies of the Met182Thr mutant of nitrite reductase: role of the axial ligand in the geometric and electronic structure of blue and green copper sites. 1464 Jun 53

Two crystal structures of the mononuclear copper(I)-nitrosyl complexes [Cu(L3)(NO)] (1) and [Cu(L3')(NO)](ClO4) (2) with the related coligands L3- (hydrotris(3-tert-butyl-5-isopropyl-1-pyrazolyl)borate) and L3' (tris(3-tert-butyl-5-isopropyl-1-pyrazolyl)methane) are presented. These compounds are then investigated in detail using a variety of spectroscopic methods. Vibrational spectra show nu(N-O) at 1698 cm(-1) and nu(Cu-NO) split at 365/338 cm(-1) for 1, which translates to force constants of 12.53 (N-O) and 1.31 mdyn/A (Cu-NO), respectively. The weak Cu-NO force constant is in agreement with the observed instability of the Cu-NO bond. Interestingly, complex 2 with the neutral coligand L3' shows a stronger N-O bond, evident from nu(N-O) at 1742 cm(-1). This difference is attributed to a true second coordination sphere effect, where the covalency of the Cu(I)-NO bond is not altered. The EPR spectrum of 1 is in agreement with the Cu(I)-NO(radical) electronic structure of the complexes, as obtained from density functional theory (DFT) calculations. In addition, an interesting trend between g parallel(gz) and the Cu-N-O angle is established. Finally, high-quality MCD spectra of 1 are presented and assigned using TD-DFT calculations. Based on the in-depth spectroscopic characterization of end-on bound NO to copper(I) presented in this work, it is possible to determine the binding mode of the Cu-NO intermediate of Cu nitrite reductase studied by Scholes and co-workers (Usov, O. M.; Sun, Y.; Grigoryants, V. M.; Shapleigh, J. P.; Scholes, C. P., J. Am. Chem. Soc. 2006, 128, 13102-13111) in solution as strongly bent (approximately 135 degrees) but likely not side-on.
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PMID:Structural and spectroscopic characterization of mononuclear copper(I) nitrosyl complexes: end-on versus side-on coordination of NO to copper(I). 1817 10