EPR spectroscopy as a probe of metal centres in biological systems

Investigating the intermediates in the reaction of ribonucleoside triphosphate reductase from Lactobacillus leichmannii: An application of HF EPR-RFQ technology

In this investigation high-frequency electron paramagnetic resonance spectroscopy (HFEPR) in conjunction with innovative rapid freeze-quench (RFQ) technology is employed to study the exchange-coupled thiyl radical-cob(II)alamin system in ribonucleotide reductase from a prokaryote Lactobacillus leichmannii. The size of the exchange coupling (Jex) and the values of the thiyl radical g tensor are refined, while confirming the previously determined (Gerfen et al. (1996) [20]) distance between the paramagnets. Conclusions relevant to ribonucleotide reductase catalysis and the architecture of the active site are presented. A key part of this work has been the development of a unique RFQ apparatus for the preparation of millisecond quench time RFQ samples which can be packed into small (0.5 mm ID) sample tubes used for CW and pulsed HFEPR--lack of this ability has heretofore precluded such studies. The technology is compatible with a broad range of spectroscopic techniques and can be readily adopted by other laboratories.

Metallomic EPR spectroscopy

Based on explicit definitions of biomolecular EPR spectroscopy and of the metallome, this tutorial review positions EPR in the field of metallomics as a unique method to study native, integrated systems of metallobiomolecular coordination complexes subject to external stimuli. The specific techniques of whole-system bioEPR spectroscopy are described and their historic, recent, and anticipated applications are discussed.