Back to Search Start Over

Thiol-Disulfide Exchange Kinetics and Redox Potential of the Coenzyme M and Coenzyme B Heterodisulfide, an Electron Acceptor Coupled to Energy Conservation in Methanogenic Archaea.

Authors :
Laird MG
Adlung N
Koivisto JJ
Scheller S
Source :
Chembiochem : a European journal of chemical biology [Chembiochem] 2024 Jan 02; Vol. 25 (1), pp. e202300595. Date of Electronic Publication: 2023 Oct 31.
Publication Year :
2024

Abstract

Methanogenic and methanotrophic archaea play important roles in the global carbon cycle by interconverting CO <subscript>2</subscript> and methane. To conserve energy from these metabolic pathways that happen close to the thermodynamic equilibrium, specific electron carriers have evolved to balance the redox potentials between key steps. Reduced ferredoxins required to activate CO <subscript>2</subscript> are provided by energetical coupling to the reduction of the high-potential heterodisulfide (HDS) of coenzyme M (2-mercaptoethanesulfonate) and coenzyme B (7-mercaptoheptanoylthreonine phosphate). While the standard redox potential of this important HDS has been determined previously to be -143 mV (Tietze et al. 2003 DOI: 10.1002/cbic.200390053), we have measured thiol disulfide exchange kinetics and reassessed this value by equilibrating thiol-disulfide mixtures of coenzyme M, coenzyme B, and mercaptoethanol. We determined the redox potential of the HDS of coenzyme M and coenzyme B to be -16.4±1.7 mV relative to the reference thiol mercaptoethanol (E <superscript>0</superscript> '=-264 mV). The resulting E <superscript>0</superscript> ' values are -281 mV for the HDS, -271 mV for the homodisulfide of coenzyme M, and -270 mV for the homodisulfide of coenzyme B. We discuss the importance of these updated values for the physiology of methanogenic and methanotrophic archaea and their implications in terms of energy conservation.<br /> (© 2023 The Authors. ChemBioChem published by Wiley-VCH GmbH.)

Details

Language :
English
ISSN :
1439-7633
Volume :
25
Issue :
1
Database :
MEDLINE
Journal :
Chembiochem : a European journal of chemical biology
Publication Type :
Academic Journal
Accession number :
37815851
Full Text :
https://doi.org/10.1002/cbic.202300595