Issue 60, 2024

Intermediates involved in the reduction of SO2: insight into the mechanism of sulfite reductases

Abstract

Sulfite reductases (SiRs) catalyze the reduction of SO32− to H2S in biosynthetic sulfur assimilation and dissimilation of sulfate. The mechanism of the 6e/6H+ reduction of SO32− at the siroheme cofactor is debated, and proposed intermediates involved in this 6e reduction are yet to be spectroscopically characterized. The reaction of SO2 with a ferrous iron porphyrin is investigated, and two intermediates are trapped and characterized: an initial Fe(III)–SO22− species, which undergoes proton-assisted S–O bond cleavage to form an Fe(III)–SO species. These species are characterized using a combination of resonance Raman (with 34S-labelled SO2), EPR and DFT calculations. Results obtained help reconcile the different proposed mechanisms for the SiRs.

Graphical abstract: Intermediates involved in the reduction of SO2: insight into the mechanism of sulfite reductases

Supplementary files

Article information

Article type
Communication
Submitted
01 May 2024
Accepted
20 Jun 2024
First published
21 Jun 2024

Chem. Commun., 2024,60, 7709-7712

Intermediates involved in the reduction of SO2: insight into the mechanism of sulfite reductases

A. Bhattacharya, S. Samanta, A. K. Nath, A. Ghatak, S. G. Dey and A. Dey, Chem. Commun., 2024, 60, 7709 DOI: 10.1039/D4CC02124J

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