Electron nuclear double resonance studies

Riedel A, S Fetzner, M Rampp, F Lingens, U Liebl, J-L Zrmmermann, W Nitschke (1995) EPR, electron spin echo envelope modulation, and electron nuclear double resonance studies of the 2Ee-2S centers of the 2-halobenzoate 1,2-dioxygenase from Burkholderia (Pseudomonas) cepacia 2CBS. J Biol Chem 270 30869-30873. 

Mukai, K. Tsuzuki, N. Ishizu, K. Ouchi, S. Fukuzawa K Electron nuclear double resonance studies of radicals produced by the Pb02 oxidation of a-tocopherol and its model compound in solution. Chem. Phys. Lipids 1981, 29, 129-135. 

ENDOR (electron nuclear double resonance) studies of diphenyl-carbene indicated a dihedral angle of 34° for this species >. 

Electron-nuclear double-resonance studies aconitase, 38 326-328 [4Fe0134S] cluster, 38 355-358 Electron paramagnetic resonance carbon monoxide oxidoreductase, 32 326-328... 

Nelson WH, Sagstuen E, Hole EO, Close DM (1998) Electron spin resonance and electron nuclear double resonance study of X-irradiated deoxyadenosine proton transfer behaviour of primary ionic radicals. Radiat Res 149 75-86... 

Hendrich, M. P., Fox, B. G., Andersson, K. K., Debrunner, P. G., and Lipscomb, J. D., 1992, Ligation of the diiron site of the hydroxylase component of methane monooxygenase. An electron nuclear double resonance study, J. Biol. Chem. 267 261n269. 

Putsch, S., Lendzian, F., Ingemarson, R., Homberg, A., Thelander, L., Lubitz, W., Lassmann, G., and Gr%oslund, A., 1999, The iron-oxygen reconstitution reaction in protein R2-tyr-177 mutants of mouse ribonucleotide reductaseoEPR and electron nuclear double resonance studies on a new transient tryptophan radical. J. Biol. Chem. 274 17696nl7704. 

H. J. D. McManus, Y. S. Kang, and L. Kevan, Electron spin resonance, electron spin echo, and electron nuclear double resonance studies of the photoieduction yield of a series of alkylmethylviologens in sodium dodecyl sulfate and dodecyltrimethylammonium chloride micelles Effect of the alkyl chain length ofthe viologen, J. Phys. Chem. 96, 5622-5628 (1992). 

McManus, H. J. D., Kang, Y. S., and Kevan, L. (1993). Electron-paramagnetic-resonance and proton matrix electron-nuclear double-resonance studies of N,N,N, N -tetramethylbenzidine photoionization in sodium dodecyl-sulfate micelles— Structural effects of added alcohols. J. Chem. Soc. Faraday Trans., 89,4085-4089. 

Kamnakaran, C., Zhang, H., Crow, J.P., Anthohne, W.E., Kalyanaraman, B., 2004. Direct probing of copper active site and free radical formed during bicarbonate-dependent peroxidase activity of bovine and human copper, zinc-superoxide dismutases. Low-temperature electron paramagnetic resonance and electron nuclear double resonance studies. J. Biol. Chem. 279, 32534—32540. 

A. Poppl, T. Rudolf, D. Michel, A pulsed electron nuclear double resonance study of the Lewis acid site nitric oxide complex in zeohte H-ZSM-5. J. Am. Chem. Soc. 120(19), 4879 880 (1998). doi 10.1021/ja9741685... 

S. Sinnecker, E. Reijerse, F. Neese and W. Lubitz, Hydrogen bond geometries from paramagnetic resonance and electron-nuclear double resonance parameters Density functional study of quinone radical anion-solvent interactions, J. Am. Chem. Soc., 2004, 126, 3280. 

Since the phenoxyls possess an S = ground state, they have been carefully studied by electron paramagnetic spectroscopy (EPR) and related techniques such as electron nuclear double resonance (ENDOR), and electron spin-echo envelope modulation (ESEEM). These powerful and very sensitive techniques are ideally suited to study the occurrence of tyrosyl radicals in a protein matrix (1, 27-30). Careful analysis of the experimental data (hyperfine coupling constants) provides experimental spin densities at a high level of precision and, in addition, the positions of these tyrosyls relative to other neighboring groups in the protein matrix. 

Electron nuclear double resonance (ENDOR) and electron spin-echo envelope modulation (ESEEM) are two of a variety of pulsed EPR techniques that are used to study paramagnetic metal centers in metalloenzymes. The techniques are discussed in Chapter 4 of reference la and will not be discussed in any detail here. The techniques can define electron-nuclear hyperfine interactions too small to be resolved within the natural width of the EPR line. For instance, as a paramagnetic transition metal center in a metalloprotein interacts with magnetic nuclei such as H, H, P, or these... 

The electron-nuclear double resonance (ENDOR) technique mentioned in the previous paragraph is used to study electron-nuclear hyperfine... 

Spectroscopic studies on the Fe-Mo protein by EPR and Mossbauer spectroscopy have shown six iron atoms each in a distinctive magnetic environment coupled to an overall S=3/2 spin system (6,7,8) and electron nuclear double resonance (ENDOR) studies suggest one molybdenum per spin system (8). The 5 Fe signals (five or six doublets) observed in the ENDOR spectra (8) indicate a rather asymmetric structure for the Fe/Mo/S aggregate in which the iron atoms roughly can be grouped into two sets of trios, each set having very similar hyperfme parameters. 

Electron paramagnetic resonance (EPR) and electron-nuclear double resonance (ENDOR) studies on frozen solutions of TDTA in tetrahydrofuran (THE) allowed estimates of its spin density distribution <2005JCD3838>. A comparison with that of TTTA <2001JMC1992> determined by similar methods shows that replacement of N of TTTA by isoelectronic C-H groups results in greater localization of spin density on the dithiazolyl ring. 

EPR spectroscopy is used widely in the study of proteins and of lipid-protein interactions.0 It has often been used to estimate distances between spin labels and bound paramagnetic metal ions.g A high-resolution EPR technique that detects NMR transitions by a simultaneously irradiated EPR transition is known as electron-nuclear double resonance (ENDOR).h... 

This method unambiguously establishes the presence of species bearing unpaired electrons (ion radicals and radicals). The ESR spectrum quantitatively characterizes the distribution of the electron density within the paramagnetic particle by hyperfine ESR structure. This establishes the nature and electronic configuration of the particle. The ESR method dominates in ion radical studies. Its modem modifications, namely, electron-nuclear double resonance (ENDOR) and electron-nuclear-nuclear triple resonance (TRIPLE), and special... 

A prototypical example of a molecular probe used extensively to study the mineral adsorbent-solution interface is the ESR spin-probe, Cu2+ (Sposito, 1993), whose spectroscopic properties are sensitive to changes in coordination environment. Since water does not interfere significantly with Cu11 ESR spectra, they may be recorded in situ for colloidal suspensions. Detailed, molecular-level information about coordination and orientation of both inner- and outer-sphere Cu2+ surface complexes has resulted from ESR studies of both phyllosilicates and metal oxyhydroxides. In addition, ESR techniques have been combined with closely related spectroscopic methods, like electron-spin-echo envelope modulation (ESEEM) and electron-nuclear double resonance (ENDOR), to provide complementary information about transition metal ion behaviour at mineral surfaces (Sposito, 1993). The level of sophistication and sensitivity of these kinds of surface speciation studies is increasing continually, such that the heterogeneous colloidal particles in soils can be investigated ever more accurately. 

In the form in which it has so far been applied to the study of carbenes, EPR spectroscopy is unable to investigate the hyperfine interactions of the unpaired spins with the constituent atomic nuclei because of the broad lines which are observed. However, the technique of electron nuclear double resonance ( endor ) promises to permit such investigations to be made, so providing even more detailed information about the electronic structure of carbenes (Hutchison, 1967). 

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