Determination of the Proton Environment of High Stability Menasemiquinone Intermediate in Escherichia coli Nitrate Reductase A by Pulsed EPR
Abstract
Background: Escherichia coli nitrate reductase A highly stabilizes a semiquinone catalytic intermediate. Results: Three proton hyperfine couplings to this radical with atypical characteristics are characterized. Conclusion: Semiquinone binding is strongly asymmetric and occurs via a single short in-plane H-bond. Significance: Learning how the protein environment tunes the semiquinone properties is crucial for understanding the quinol utilization mechanism by energy-transducing enzymes.
Domains
Life Sciences [q-bio]
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