Infrared Spectroscopy of the nitrogenase MoFe Protein Under Electrochemical Control: Potential-Triggered CO binding

Authors

P. Paengnakorn, University of Oxford
Philip A. Ash, University of Oxford
Sudipta K. Shaw, Utah State University
Karamatullah Danyal, Utah State University
T. Chen, University of Oxford
Dennis R. Dean, Virginia Polytechnic Institute and State University
Lance C. Seefeldt, Utah State University
Kylie A. Vincent, University of Oxford

Document Type

Article

Journal/Book Title

Chemical Science

Publication Date

10-27-2016

Publisher

Royal Society of Chemistry

Volume

8

Issue

2

First Page

1500

Last Page

1505

Abstract

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-98^Tyr→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.

Comments

http://pubs.rsc.org/en/Content/ArticleLanding/2017/SC/C6SC02860H#!divAbstract

Recommended Citation

Paengnakorn, P., Ash, P.A., Shaw, S., Danyal, K., Chen, T., Dean, D.R., Seefeldt, L.C., Vincent, K.A. Infrared spectroscopy of the nitrogenase MoFe protein under electrochemical control: potential-triggered CO binding (2017) Chemical Science, 8 (2), pp. 1500-1505.