Format

Send to

Choose Destination
Biochem Soc Trans. 2012 Jun 1;40(3):501-7. doi: 10.1042/BST20120083.

Redox, haem and CO in enzymatic catalysis and regulation.

Author information

1
Department of Biological Chemistry, University of Michigan, Ann Arbor, MI 48109, U.S.A. sragsdal@umich.edu

Abstract

The present paper describes general principles of redox catalysis and redox regulation in two diverse systems. The first is microbial metabolism of CO by the Wood-Ljungdahl pathway, which involves the conversion of CO or H2/CO2 into acetyl-CoA, which then serves as a source of ATP and cell carbon. The focus is on two enzymes that make and utilize CO, CODH (carbon monoxide dehydrogenase) and ACS (acetyl-CoA synthase). In this pathway, CODH converts CO2 into CO and ACS generates acetyl-CoA in a reaction involving Ni·CO, methyl-Ni and acetyl-Ni as catalytic intermediates. A 70 Å (1 Å=0.1 nm) channel guides CO, generated at the active site of CODH, to a CO 'cage' near the ACS active site to sequester this reactive species and assure its rapid availability to participate in a kinetically coupled reaction with an unstable Ni(I) state that was recently trapped by photolytic, rapid kinetic and spectroscopic studies. The present paper also describes studies of two haem-regulated systems that involve a principle of metabolic regulation interlinking redox, haem and CO. Recent studies with HO2 (haem oxygenase-2), a K+ ion channel (the BK channel) and a nuclear receptor (Rev-Erb) demonstrate that this mode of regulation involves a thiol-disulfide redox switch that regulates haem binding and that gas signalling molecules (CO and NO) modulate the effect of haem.

PMID:
22616859
PMCID:
PMC3553215
DOI:
10.1042/BST20120083
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for HighWire Icon for PubMed Central
Loading ...
Support Center