Infrared spectroscopy of the nitrogenase MoFe protein under electrochemical control: potential-triggered CO binding

Journal article

We demonstrate electrochemical control of the nitrogenase MoFe protein, in the absence of Fe protein or ATP, using europium (III/II) polyaminocarboxylate complexes as electron transfer mediators. This allows the potential dependence of proton reduction and inhibitor (CO) binding to the active site FeMo-cofactor to be established. Reduction of protons to H2 is catalyzed by the wild type MoFe protein and β-98Tyr→His and β 99Phe→His variants of the MoFe protein at potentials more negative than -800 mV (vs SHE), with greater electrocatalytic proton reduction rates observed for the variants compared to the wild-type protein. Electrocatalytic proton reduction is strongly attenuated by carbon monoxide (CO), and the potential-dependence of CO binding to the FeMo-cofactor is determined by in situ infrared (IR) spectroelectrochemistry. The vibrational wavenumbers for CO coordinated to the FeMo-cofactor are consistent with earlier IR studies on the MoFe protein with Fe protein/ATP as reductant showing that electrochemically generated states of the protein are closely related to states generated with the native Fe protein as electron donor.

Authors: Paengnakorn, P; Ash, P; Shaw, S; Danyal, K; Chen, T

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Royal Society of Chemistry
• Journal: Chemical Science
• Publication date: 2016-10-27
• Acceptance date: 2016-10-26
• DOI: 10.1039/C6SC02860H
• EISSN: 2041-6520
• ISSN: 2041-6539
• Keywords: Article