scholarly journals Electron nuclear double-resonance (ENDOR) spectroscopy of amine oxidase from pig plasma

1986 ◽  
Vol 237 (2) ◽  
pp. 609-612 ◽  
Author(s):  
G J Baker ◽  
P F Knowles ◽  
K B Pandeya ◽  
J B Rayner
Keyword(s):  
Hyperfine Coupling ◽  
Amine Oxidase ◽  
Double Resonance ◽  
Spectroscopic Studies ◽  
Water Molecules ◽  
Electron Nuclear Double Resonance ◽  
Endor Spectroscopy ◽  
Amino Acid Histidine ◽  
Plasma Amine Oxidase ◽  
Hyperfine Couplings

Electron nuclear double-resonance (‘ENDOR’) spectroscopic studies on pig plasma amine oxidase have been carried out at 15 K. Deuterium-exchange studies show the presence of two sets of exchangeable protons, probably from two water molecules; from the magnitude of their hyperfine couplings, one is assigned to be equatorially, and the other axially, co-ordinated. Only one 14N hyperfine coupling is observed, suggesting that the bonding of all amino acid (histidine) or organic cofactor ligands is similar. Upon addition of azide, a further hyperfine coupling to nitrogen is observed which is smaller than that observed for the native enzyme; the hyperfine couplings to the remaining nitrogens are slightly altered.

scholarly journals E.p.r.-spectroscopic studies on the molybdenum–iron site of nitrogenase from Clostridium pasteurianum

1989 ◽  
Vol 262 (1) ◽  
pp. 349-352 ◽  
Author(s):  
G N George ◽  
R E Bare ◽  
H Y Jin ◽  
E I Stiefel ◽  
R C Prince
Keyword(s):  
Hyperfine Coupling ◽  
Double Resonance ◽  
Spectroscopic Studies ◽  
Clostridium Pasteurianum ◽  
Iron Site ◽  
Electron Nuclear Double Resonance ◽  
Molybdenum Iron Protein ◽  
Iron Protein ◽  
Hyperfine Splittings

The e.p.r. spectroscopy of the nitrogenase molybdenum-iron protein from Clostridium pasteurianum was re-investigated. The sharpness of the delta Ms = +/- 3 g′z peak from the +/- 3/2 Kramer's doublet enables the observation and quantification of incompletely resolved hyperfine splittings from the stable magnetic nuclei 95Mo and 57Fe in samples enriched in these isotopes. No couplings to 1H or 17O could be discerned by examination of spectra from samples exchanged into 2H2O and H2(17)O respectively. Simulation of the spectrum from 95Mo-enriched samples yields a hyperfine coupling of 2.9 MHz, and indicates that the earlier electron-nuclear-double-resonance-derived estimate of 8.1 +/- 0.2 MHz is substantially in error.

Copper x-ray absorption spectroscopic studies of the bovine plasma amine oxidase-sulfide complex

1988 ◽  
Vol 27 (21) ◽  
pp. 3859-3861 ◽  
Author(s):  
Robert A. Scott ◽  
Cheryl E. Cote ◽  
David M. Dooley
Keyword(s):  
Amine Oxidase ◽  
Spectroscopic Studies ◽  
X Ray ◽  
Bovine Plasma ◽  
Plasma Amine Oxidase ◽  
X Ray Absorption

scholarly journals Electron Nuclear Double Resonance of the Chlorophyll Triplet State in the Water-Soluble Chlorophyll Protein from Brassica oleracea: Investigation of the Effect of the Binding Site on the Hyperfine Couplings

2020 ◽  
Vol 51 (9-10) ◽  
pp. 925-937
Author(s):  
Alessandro Agostini ◽  
Daniel M. Palm ◽  
Harald Paulsen ◽  
Marilena Di Valentin ◽  
Donatella Carbonera
Keyword(s):  
Triplet State ◽  
Brassica Oleracea ◽  
Double Resonance ◽  
Water Soluble ◽  
Triplet States ◽  
Triplet Energy ◽  
Electron Nuclear Double Resonance ◽  
Light Harvesting Complexes ◽  
Chlorophyll Protein ◽  
Hyperfine Couplings

Abstract An investigation of the photoexcited triplet state of chlorophyll (Chl) a in the water-soluble chlorophyll protein (WSCP) of Brassica oleracea has been carried out by means of electron-nuclear double resonance (ENDOR), achieving a complete assignment of the observed hyperfine couplings corresponding to methine protons and methyl groups of Chl a triplet state. The triplet-state properties, and in particular the hyperfine couplings, were found to be similar to those previously reported for Chl a in the WSCP of Lepidium virginicum. Therefore, the porphyrin ring deformation observed in Brassica oleracea WSCP seems to only slightly affect the spin density of 3Chl a. This may be relevant when considering the robustness of triplet–triplet energy transfer mechanisms, relying on wavefunction overlap, in systems, such as the photosynthetic light-harvesting complexes, in which Chl triplet states with distorted geometries are involved.

scholarly journals Electron-nuclear-double-resonance studies of spinach plastocyanin

1983 ◽  
Vol 215 (1) ◽  
pp. 209-212 ◽  
Author(s):  
H Yokoi ◽  
Y Ohba ◽  
T Takabe
Keyword(s):  
Double Resonance ◽  
Electron Nuclear Double Resonance ◽  
Hyperfine Couplings

Electron-nuclear-double-resonance (ENDOR) studies of spinach plastocyanin revealed that 14N-hyperfine couplings from its two co-ordinated imidazole groups are characteristically small in anisotropy and relatively high in ENDOR frequencies and that the two imidazole groups are magnetically equivalent. The relatively strong copper-imidazole co-ordinate bonds of plastocyanin are interpreted to be a result of the coexistence of a strong copper-thiol co-ordinate bond.

Mo(V) co-ordination in the periplasmic nitrate reductase from Paracoccus pantotrophus probed by electron nuclear double resonance (ENDOR) spectroscopy

2002 ◽  
Vol 363 (3) ◽  
pp. 817-823 ◽  
Author(s):  
Clive S. BUTLER ◽  
Shirley A. FAIRHURST ◽  
Stuart J. FERGUSON ◽  
Andrew J. THOMSON ◽  
Ben C. BERKS ◽  
...  
Keyword(s):  
Nitrate Reductase ◽  
Double Resonance ◽  
Electron Nuclear Double Resonance ◽  
Time Resolved ◽  
Strongly Coupled ◽  
Periplasmic Nitrate Reductase ◽  
Weakly Coupled ◽  
Endor Spectroscopy ◽  
X Band ◽  
Paracoccus Pantotrophus

The first electron nuclear double resonance (ENDOR) study of a member of the Mo-bis-molybdopterin guanine dinucleotide family of molybdoenzymes is presented, using the periplasmic nitrate reductase from Paracoccus pantotrophus. Rapid freeze-quenched time-resolved EPR revealed that during turnover the intensity of a Mo(V) EPR signal known as High-g [resting] increases. This signal is split by two interacting protons that are not solvent-exchangeable. X-band proton-ENDOR analysis resolved broad symmetrical resonance features that arose from four classes of protons weakly coupled to the Mo(V). Signals from two of these were lost upon exchange into deuterated buffer, suggesting that they may originate from OH− or H2O groups. One of these signals was also lost when the enzyme was redox-cycled in the presence of azide. Since these protons are very weakly coupled OH/H2O groups, they are not likely to be ligated directly to the Mo(V). This suggests that protonation of a Mo(VI)=O group does not occur on reduction to Mo(V), but most probably accompanies reduction of Mo(V) to Mo(IV). A resonance feature from a more strongly coupled proton, that was not lost following exchange into deuterated buffer, could also be resolved at 22–24MHz. The anisotropy of this feature, determined from ENDOR spectra collected at a range of field positions, indicated a Mo—proton distance of approx. 3.2Å, consistent with this being one of the β-methylene protons of a Mo—Cys ligand.

Electron Spin Resonance and Electron Nuclear Double Resonance Spectroscopy: Application to the Study of Trapped Electrons

1980 ◽  
Vol 34 (3) ◽  
pp. 293-295 ◽  
Author(s):  
Harold C. Box ◽  
Harold G. Freund
Keyword(s):  
Electron Spin Resonance ◽  
Electron Spin ◽  
Double Resonance ◽  
Resonance Spectroscopy ◽  
Electron Nuclear Double Resonance ◽  
Trapped Electrons ◽  
V Band ◽  
Endor Spectroscopy ◽  
Hydroxy Proton ◽  
Spin Resonance

V band electron spin resonance-ENDOR spectroscopy has been applied to the study of “trapped” electrons in single crystals of polyhydroxy and carbohydrate compounds X-irradiated at low temperature. Evidence is presented from ENDOR measurements of hydroxy proton couplings that electrons are stabilized at intermolecular sites. The electron can be stabilized in the dipole fields of two or three hydroxy groups.

Electron nuclear double resonance study of a nitrogen centre in diamond

1966 ◽  
Vol 295 (1441) ◽  
pp. 99-106 ◽  
Keyword(s):  
Hyperfine Coupling ◽  
Double Resonance ◽  
Axially Symmetric ◽  
Electron Nuclear Double Resonance ◽  
Quadrupole Coupling ◽  
Coupling Parameters ◽  
Small Change

Endor measurements on a type 1b diamond with paramagnetic nitrogen centres were made at 4.2, 77 and 300 °K by means of a 35000 Mc/s spectrometer. The axially symmetric nitrogen hyperfine coupling and quadrupole coupling parameters at 4.2 °K are A iso. , = 92.228 ± 0.001, A aniso. = 10.903 ± 0.002, P = – 3.974 ± 0.001 Mc/s. A small change of hyperfine coupling with temperature was observed.

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