Application of EPR Spectroscopy to the

APPLICATION OF EPR SPECTROSCOPY TO THE STRUCTURAL AND FUNCTIONAL STUDY OF IRON-SULFUR PROTEINS... 

Application of EPR Spectroscopy to the Structural and Functional Study of Iron-Sulfur Proteins Bruno Guigliarelli and Patrick Bertrand... 

These techniques are applicable only to paramagnetic Mo(V) centers, but the EPR parameters are extremely sensitive to coordination changes at the molybdenum center 17, 64). The molybdenum and ligand hyperfine splittings can provide additional information about the coordination environment of the molybdenum(V) species and the chemical reactions at the molybdenum center. EPR spectra from xanthine oxidase were first reported in 1959 by Bray et al. (65), and Bray and co-workers have continued to develop the application of EPR spectroscopy to molybdenum enzymes 17, 64). In 1966 it was shown (66) that mixing [Mo04] with dithiols produced EPR signals with (g) and (A( Mo)) values similar to those of xanthine oxidase. Only recently, however, have the structures of such thiolate complexes been determined (see Section IV.B.2.b). 39) and P (67) ENDOR spec-... 

The aim of this review is to provide an introduction to the basic principles, sample requirements, and applications of EPR spectroscopy to biological systems. The emphasis is on the factors that are important for measurements on conventional X-band EPR spectrometers. Interpretation of spectra or specialized techniques are not discussed. Information on these topics and more in-depth treatments can be found in a number of monographs on EPR spectroscopy. " ... 

In this review the application of EPR spectroscopy to eleven t)q)es of catalytic reactions is described. Distribution rights for all socialist countries Akademie-Verlag, Berlin... 

The requirement of elevated temperatures calls for designing special reaction cells that can be heated inside the EPR cavity and connected to some equipment for dosing reactant mixtures and analyzing product compositions. Both homemade and commercial solutions have been successfully introduced to accomplish this, paving the way toward the in situ application of EPR spectroscopy in the past two decades. An example of a cell design is given in Figure 20. 

Sojka, Z. (1995). Molecular Aspects of Catalytic Reactivity. Application of EPR Spectroscopy to Studies of the Mechanism of Heterogeneous Catalytic Reactions, Catal. Rev. Set Eng., 37, pp. 461-512. 

The applications of EPR spectroscopy reviewed in the present chapter are based on the sensitivity of the spectrum displayed by iron-sulfur centers to various characteristics, such as the redox state of the center, the distribution of the valences on the iron ions, the nature and the geometry of the ligands, and the presence of nearby paramagnetic species. Although considerable progress has been made during the past few years in the quantitative analysis of these various effects in the case of the conventional iron-sulfur centers described in Section II, the discovery of centers exhibiting unusual EPR properties as... 

For a more advanced treatment of the theory and applications of EPR spectroscopy, the reader is referred to the text by Weil et... 

Styring and coworkers demonstrated the application of EPR spectroscopy of the different EPR signatures of PS II to monitor certain regions of PS II during photophosphorylation of core proteins, which is known to control repair of PS... 

Controlled potential electrolysis or coulometry can be used to generate radical ions in quantities sufficient for study by appropriate techniques such as optical or EPR spectroscopy. This method is routinely applied to characterize radical anions and has also been used extensively for studying radical cations. However, the application of eoulometric techniques to the study of strained ring compounds is severely limited, even more than the application of cyclic voltammetry, by the limited stability of their one-electron oxidation products. 

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