Newly Developed Time-Resolved EPR Techniques for the Study of Cytochrome C Oxidase
We present recent results from two new time-resolved EPR techniques used to probe structure and function of cytochrome c oxidase. The first of these, which we have used at cryogenic temperatures, is pulse field-sweep EPR. With this we can resolve hyperfine couplings of the CuA nucleus in cytochrome Oxidase, where such couplings are not directly resolved by straight EPR. This method is a technically simpler alternative to other double resonance techniques. The second technique is an ambient temperature technique to follow oxygen consumption by cytochrome oxidase. This technique uses an oxygen-sensitive spin probe to report the concentration of oxygen in solution. It is feasible to use this spin probe technique together with stopped flow. O2 kinetics have been followed both under aerobic conditions where O2 consumption is limited by cytochrome c reductant and under conditions where low oxygen concentration limits the rate of oxygen consumption.
KeywordsCytochrome Oxidase Hyperfine Coupling Spin Probe Microwave Pulse Field Sweep
(electron paramagnetic resonance)
(electron nuclear souble resonance)
(pulse field sweep EPR))
- "spin amide"
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