Work

An electrochemical perspective on human sulfite oxidase as a potential nitrite reductase

Year: 2025

Type: article

Abstract: The Mo-dependent enzyme human sulfite oxidase (HSO) oxidises highly neurotoxic sulfite to benign sulfate in the final step of cysteine catabolism. Although sulfite is its only known physiological substrate, HSO has been suggested to play a role in the generation of nitric oxide (NO) from nitrite under ischemic conditions. In this work we have investigated the electrochemically driven nitrite reductase activity of HSO mediated by the benzyl viologen radical cation. We show that HSO can act as an effective nitrite reductase with a K M value of 3.5 mM at pH 7. A heme-free variant of HSO behaves similarly. We also demonstrate electrochemically driven tandem sulfite oxidation and nitrite reduction with HSO using a known Fe III coordination compound as mediator. Significant pH-dependence of catalytic activity is found.

Source: Journal of Inorganic Biochemistry

DOI: 10.1016/j.jinorgbio.2025.113159

Authors: Peter D. Giang, Joan Zapiter, Jiayun Zhou, Alexander T. Kaczmarek, Günter Schwarz, Paul V. Bernhardt

Institutions: The University of Queensland, University of Cologne

Language: English

Topic: Metalloenzymes and iron-sulfur proteins

Subfield: Renewable Energy, Sustainability and the Environment

Field: Energy

Domain: Physical Sciences

Open Access status: hybrid

Estimated APC paid: $4,220

Funders: University of Queensland, Australian Research Council