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- Title
Redox, haem and CO in enzymatic catalysis and regulation.
- Authors
Ragsdale, Stephen W.; Li Yi; Bender, Güneş; Gupta, Nirupama; Yan Kung; Lifen Yan; Stich, Troy A.; Doukov, Tzanko; Leichert, Lars; Jenkins, Paul M.; Bianchetti, Christopher M.; George, Simon J.; Cramer, Stephen P.; Britt, R. David; Jakob, Ursula; Martens, Jeffrey R.; Phillips, Jr, George N.; Drennan, Catherine L.
- 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.
- Subjects
OXIDATION-reduction reaction; HEME; METABOLIC regulation; CARBON oxides; MICROBIAL metabolism; CATALYSIS; CARBON monoxide dehydrogenase; ADENOSINE triphosphate
- Publication
Biochemical Society Transactions, 2012, Vol 40, Issue 3, p501
- ISSN
0300-5127
- Publication type
Article
- DOI
10.1042/BST20120083