Implications for the mechanism of sulfite oxidizing enzymes from pulsed EPR spectroscopy and DFT calculations for "difficult" nuclei
Related Experiment Video
Updated: Jun 4, 2026

EPR Monitored Redox Titration of the Cofactors of Saccharomyces cerevisiae Nar1
Published on: November 26, 2014
John H Enemark1, Arnold M Raitsimring, Andrei V Astashkin
1Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721-0041, USA. jenemark@u.arizona.edu
Abstract:
The catalytic mechanisms of sulfite oxidizing enzymes (SOEs) have been investigated by multi-frequency pulsed EPR measurements of "difficult" magnetic nuclei (35.37Cl, 33S, 17O) associated with the Mo(v) center. Extensive DFT calculations have been used to relate the experimental magnetic resonance parameters of these nuclei to specific active site structures. This combined spectroscopic and computational approach has provided new insights concerning the structure/function relationships of the active sites of SOEs, including: (i) the exchange of oxo ligands; (ii) the nature of the blocked forms; and (iii) the role of Cl- in low pH forms.
More Related Videos
Related Concept Videos
Electron Paramagnetic Resonance (EPR) Spectroscopy: Organic Radicals
¹H NMR: Interpreting Distorted and Overlapping Signals
As Δν decreases and the signals move closer, the doublets appear increasingly distorted. The intensities of the inner lines increase at the cost of those of the outer lines as the signals are slanted or...
Insensitive Nuclei Enhanced by Polarization Transfer (INEPT)
Crystal Field Theory - Octahedral Complexes
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
Nuclear Overhauser Enhancement (NOE)
UV–Vis Spectroscopy: Molecular Electronic Transitions

