Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: HUMANGGP:001372 (ESR)
 7,313 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Optical and ESR spectra of erythrocyte superoxide dismutase denaturated with acid and alkali are described. Sharp changes in activity and spectra were found. "Residual" activity of alkaline denaturated protein was higher than of acidic denaturated sample. It is suggested that covalent bonding copper-nitrogen is essential for superoxide dismutase activity of the protein or synthetic copper complexes.
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PMID:[Acid and alkaline denaturation of superoxide dismutase]. 0 Oct 99

10(7) mouse ascites tumor cells/ml incubated at 37 degrees C in 0.5 to 1.0 X 10(-4) M Janus green B or in 1.0 X 10(-4) M phenazine methosulphate are destroyed in 100 per cent oxygen atmosphere but remain transplantable in nitrogen atmosphere. The "sensitizing" effect of oxygen can be substituted by SH inhibitors (iodoacetic acid, iodoacetamide and their spinlabelled variants) as well as by some nitroxide free radicals. The "oxygen effect" is blocked by mercaptoethanole or cooling. Compared with the spectrum of native cells a more symmetrical singlet of larger amplitude, approximately g = 2 value, arose in the ESR spectrum of Janus green B treated cells. The "oxygen effect" observed in the presence of Janus green B differs in several ways from the oxygen effect of ionizing radiation and from the "photodynamic" effect.
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PMID:Study on the "toxic oxygen effect" of Janus green B in mouse ascites tumour cells. 7 98

High resolution electron spin resonance spectra of the stepwise formation of CN- complexes of Co(II) and Cu(II) carbonic anhydrase show that both metal enzymes form successive 1:1 and 2:1 addition products with CN- at 112 K. The 1:1 complex with the Cu(II) enzyme has a rhombic ESR spectrum similar to the spectra of the 1:1 complexes of the Cu(II) enzyme with CH3COO-, OCN-, N3-, and SH-. The 1:1 complex with the CO(II) enzyme shows a broad resonance at 10 K indicating the presence of high spin Co(II). Previous optical, ESR, and magnetic susceptibility data suggest that the 1:1 complexes are 4-coordinate. At high concentrations of 13CN- the Cu(II) enzyme forms a 2:1 CN- complex with a shift to an axial ESR signal showing ligand nuclear superhyperfine structure from two magnetically equivalent equatorial nitrogen nuclei of the protein and two magnetically equivalent equatorial carbon ligands from two 13CN- anions. Under the same conditions a structurally analogous dicyanide complex of the co(II) enzyme forms with the appearance of and axial ESR signal typical of low spin Co(II). Ligand nuclear superhyperfine structure shows the presence of an axial protein nitrogen as ligand and two magnetically equivalent equatorial carbon ligands from two 13CN- anions. The dicyanide complexes of the Co(II) and Cu(II) enzymes form completely only in frozen solutions and analysis of the ESR spectra show them to have a 5-coordinate square pyrimidal geometry. Comparison of the ligand superhyperfine structure on the ESR signals of both dicyanide complexes shows that there are three nitrogen nuclei of the protein present as ligands at the metal binding site; one axial and two equatorial in the dicyanide complexes. A transient 5-coordinate intermediate might play a role in the mechanism of action of carbonic anhydrase by facilitating ligand exchange reactions within the inner coordination sphere of the Zn(II) ion at the active center.
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PMID:Structure of the active site of carbonic anhydrase as determined by electron spin resonance. 16 45

The reduction of adrenal ferredoxin (adrenodoxin) at low temperatures was investigated in order to separate local modifications of the active centre of the protein on its reduction, from the conformational transition which seems to accompany the change of the redox state of the irons; The ESR spectra of the states of the protein, where the reduced active centre is to be found by the "oxidized" conformation of the apoprotein, were obtained. The transition from the states of the protein to the state which occurs on its chemical reduction at room temperature was also investigated. The results of the work support the view that conformational changes in proteins (enzymes) which take place while they are functioning proceed after modifications of the active centres (change of the redox state, adsorption of a substrate, etc.), and are essentially caused by them. Adrenal ferredoxin was the third subject in our studies of the intermediate states of proteins which appear after reduction of their active centres by means of electrons trapped in water-ethylene glycol mixtures at the temperature of liquid nitrogen [1, 2]. In the reduced state, the active centre of the protein has an ESR signal with a g-factor of 1.94 [3, 4] which is convenient for our purposes.
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PMID:Studies on the conformational changes of metalloproteins induced by electrons in water-ethylene glycol solutions at low temperatures. III. Adrenal ferredoxin. 16 33

To detect changes in the oxygen concentration during biochemical reactions, the exchange broadening in the ESR spectra of nitroxide radicals caused by the dissolved oxygen, has been used. The measurements have been carried out using changes in the width either of the proton hyperfine structure components or of the nitrogen hyperfine structure line with an unresolved proton structure. Detection of mitochondrial respiration in a volume of about 10(-3) cm 3 and respiration for 100 +/- 5 liver cells in a volume of about 10(-4) cm3 has been carried out.
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PMID:Detection of the kinetics of biochemical reactions with oxygen using exchange broadening in the ESR spectra of nitroxide radicals. 19 84

Total content of Fenh and its amounts incorporated into paramagnetic dinitrozyl complexes of Fenh (complexes 2.03) which are formed in vitro in homogenates of mouse liver and yeast preparations treated with nitrogen oxide was determined by means of chemical and ESR methods. Formation of the complexes 2.03 in the liver homogenate is limited by the content of easily dyalized weakly bound Fenh, in yeasts--by the content of pair RS-groups. It is suggested that in the liver preparation Fenh incorporated into the complexes 2.03 is determined by the interaction of reduction cytoplasm agents with ferritin. A change in the content of Fenh may affect the appearance and disappearance of the complexes 2.03 in animal tissues in vivo.
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PMID:[Factors influencing formation of dinitrosyl complexes of non-heme iron in vitro preparations of mouse liver and yeasts]. 19 16

The state I in equilibrium state II transients in bean leaves were studied by ESR method at various temperatures. P700 photooxidation induced by far-red light after leaf adaptation to darkness demonstrated two phases. This kinetics correlated with two overshuts in the kinetics of P700+ reduction observed after additional switching on the light exciting Photosystem II. In the atmosphere of gaseous nitrogen P700 behaviour was reversibly modified. Multiphase character of P700 kinetics correlated with the state I in equilibrium state II phenomenon as measured by chlorophyll a fluorescence from Photosystem II. The rate-limiting step at the acceptor side of Photosystem I electron transport chain may be considered as a point controlling the state of intact chloroplasts.
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PMID:[Effect of illumination prehistory on P700 redox transition kinetics in bean leaves]. 46 63

Muscle breakdown and repair were measured by metabolic balance techniques in a patient with polymyositis who was being treated with prednisolone and azathioprine. Changes in body muscle mass that had been estimated from nitrogen and phosphorus balances correlated with antropometric assessments of thigh muscle mass and quadriceps strength. Decline in muscle strength was associated with a net rate of muscle breakdown of 148 g/day. Recovery was associated with a net rate of muscle repair of up to 100 g/day. Early reduction in corticosteroid treatment appeared to enhance the rate of repair. Changes in the isometric contraction force of the quadriceps muscle (but not in clinical symptoms, plasma creatine kinase [CK] or erythrocyte sedimentation rate [ESR] were found to reliably indicate whether the muscle was in a state of breakdown or repair. Treatment of the individual patient may be quantitatively monitored by metabolic balance studies or, more simply, by measurement of muscle strength.
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PMID:Muscle breakdown and repair in polymyositis: a case study. 50 7

Reduction of copper amine oxidase with substrate led to the appearance of a free radical which can be detected in anaerobiosis by ESR and optical spectroscopy. The origin of this radical was examined through studies of the semiquinones of 6-hydroxydopamine, an analogue of the recently identified cofactor 6-hydroxydopa. The ESR spectrum of the 6-hydroxydopamine radical was too narrow to account for the enzyme radical signal; however, after spontaneous reaction with primary amines the hyperfine splittings and spectral width obtained by modulation broadening became very similar to those observed for the oxidase radical species. This effect was ascribed to covalent binding of a nitrogen atom directly to the aromatic ring structure, suggesting that the amine oxidase radical is an amino-6-hydroxydopa semiquinone. Identical ESR spectra were obtained using the amines putrescine, cadaverine, p-[(dimethylamino)methyl]benzylamine, and ethylenediamine; these oxidase substrates gave identical enzyme radical spectra as well. The interaction between cofactor and substrate was proved unambiguously by the technique of isotopic labeling: addition of [15N2]ethylenediamine instead of the normal 14N-labeled compound changed the ESR spectra of both the enzyme radical and its 6-hydroxydopamine counterpart. The results were confirmed by optical spectroscopy measurements; 6-hydroxydopamine and oxidized 6-hydroxydopamine gave spectra identical to those of reduced and oxidized amine oxidase, respectively. The 6-hydroxydopamine radical showed a sharp peak at 440 nm; upon addition of amines the maximum shifted to 460 nm, as found for the enzyme. It is proposed that copper amine oxidase represents the first example of a mixed substrate-cofactor radical within the family of tyrosine radical enzymes.
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PMID:A substrate-cofactor free radical intermediate in the reaction mechanism of copper amine oxidase. 131 34

Results are reported of a pH-metric and spectroscopic (CD and ESR) study of the complexes formed between the pseudo-peptide 1-hydroxy-4-(Gly-His-Lys)-anthraquinone (Q-GHK) since, when complexed to copper ions, Q-GHK has been shown to be very effective in promoting the formation of free radicals and inducing DNA cleavage. Q-GHK forms very stable complexes with copper, the major species being bonded to three nitrogen donors in the coordination plane: an imidazole-N of the His residue and the peptide nitrogens of the Gly and His residues. This species is probably stabilized through bonding of the fourth planar coordination site of Cu(II) to the 9-anthraquinone oxygen. At high Q-GHK:copper ratios a second Q-GHK molecule is coordinated through its imidazole-N donor.
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PMID:The coordination of copper(II) to 1-hydroxy-4-(glycyl-histidyl-lysine)-anthraquinone; a synthetic model of anthraquinone anti-cancer drugs. 132 88


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