Deconstructing the electron transfer chain in a complex molybdoenzyme: Assimilatory nitrate reductase from Neurospora crassa.

Autor: Kalimuthu P; School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane 4072, Australia., Kruse T; Department of Plant Biology, Technische Universitaet, Braunschweig, Spielmannstrasse 7, 38106 Braunschweig, Germany., Bernhardt PV; School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane 4072, Australia. Electronic address: p.bernhardt@uq.edu.au.
Jazyk: angličtina
Zdroj: Biochimica et biophysica acta. Bioenergetics [Biochim Biophys Acta Bioenerg] 2021 Mar 01; Vol. 1862 (3), pp. 148358. Date of Electronic Publication: 2020 Dec 24.
DOI: 10.1016/j.bbabio.2020.148358
Abstrakt: Nitrate reductase (NR) from the fungus Neurospora crassa is a complex homodimeric metallo-flavoenzyme, where each protomer contains three distinct domains; the catalytically active terminal molybdopterin cofactor, a central heme-containing domain, and an FAD domain which binds with the natural electron donor NADPH. Here, we demonstrate the catalytic voltammetry of variants of N. crassa NRs on a modified Au electrode with the electrochemically reduced forms of benzyl viologen (BV 2+ ) and anthraquinone sulfonate (AQS - ) acting as artificial electron donors. The biopolymer chitosan used to entrap NR on the electrode non-covalently and the enzyme film was both stable and highly active. Electrochemistry was conducted on two distinct forms; one lacking the FAD cofactor and the other lacking both the FAD and heme cofactors. While both enzymes showed catalytic nitrate reductase activity, removal of the heme cofactor resulted in a more significant effect on the rate of nitrate reduction. Electrochemical simulation was carried out to enable kinetic characterisation of both the NR:nitrate and NR:mediator reactions.
(Copyright © 2020 Elsevier B.V. All rights reserved.)
Databáze: MEDLINE
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