81] Vanadyl(IV) electron nuclear double resonance/electron spin echo envelope modulation spin probes

Abstract

Publisher Summary The oxycation vanadyl (IV), VO 2+ , has been historically used as an electron paramagnetic resonance (EPR) spin probe of metal binding sites in proteins. More recently, VO 2+ has been employed as an electron nuclear double resonance (ENDOR) and electron spin echo envelope modulation (ESEEM)) spin probe. These higher resolution resonance techniques provide more detailed information about the metal binding site than is possible with EPR spectroscopy alone. In particular, magnetic nuclei with couplings less than the natural width of 5-15 G of the EPR line can be identified and studied by ENDOR or ESEEM. In favorable cases, one can obtain information about the geometrical arrangement of magnetic nuclei in the vicinity of the electron spin as well. This chapter discusses some of the salient features of the EPR spectra of vanadyl(IV)-protein complexes and then gives a synopsis of some recent ENDOR and ESEEM work.