EPR of CobaltSubstituted Zinc Enzymes

Authors: Brian Bennett

Publish Date: 2010

Volume: , Issue: , Pages: 345-370

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Abstract

CoII is sometimes utilized as a spectroscopically active substitute for ZnII in enzymes Metal binding sites in enzymes that contain catalytically active ZnII generally yield highspin S = 3/2 CoII ions when substituted with cobalt and these provide EPR spectra rich in information Extracting this information involves an appreciation of the extent to which the properties of CoII mirror those of ZnII careful sample preparation and biochemical characterization careful recording of the EPR data and the ability to interpret spectra in a quantitative way Here the applicability of CoII as a structural and functional mimic of ZnII in enzymes is considered and a brief update of EPR studies in the literature is presented Methods of substitution of ZnII by CoII are described Recording EPR spectra of highspin CoII that will provide useful information is not a trivial exercise and experimental considerations are discussed in some detail The analysis of EPR spectra in terms of spinHamiltonian parameters is described along with their interpretation in structural terms Complementary techniques to EPR are very briefly discussed and a case study is presented as an example of how EPR of CoII can provide mechanistic information on a zinc enzyme that is unavailable by other techniques

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