Mechanistic enzymology of CO dehydrogenase from Clostridium thermoaceticum
The final steps in acetyl-CoA biosynthesis by anaerobic bacteria are performed by carbon monoxide dehydrogenase (CODH), a nickel/iron-sulfur protein. An important achievement was to establish conditions under which acetyl-CoA synthesis by purified enzymes equals the in vivo rate of acetate synthesis. Under these optimized conditions we established that the rate limiting step in the synthesis of acetyl-CoA from methyl-H[sub 4]folate, CO and CoA is likely to be the methylation of CODH by the methylated corrinoid/iron-sulfur protein. We then focused on stopped flow studies of this rate limiting transmethylation reaction and established its mechanism. We have studied the carbonylation of CODH by infrared and resonance Raman spectroscopy and determined that the [Ni-Fe[sup 3-4]S[sub 4]]-CO species which has been characterized by magnetic resonance methods can be described as [Ni-X-Fe[sub 3-4]S[sub 4]]-C[equivalent to]O. We showed that this species is the catalytically competent precursor of the carbonyl group of acetyl-CoA. We have made progress in the synthesis of seleno-coenzyme A, which we will use to probe the binding of CoA to CODH. We also have compared the CODH from Methanosarcina thermophila with the C. thermoaceticum enzyme by EPR and electrochemical methods and found that the metal sites of these enzymes are remarkably similar given the evolutionary separation between archaea and bacteria domains.
- Research Organization:
- Nebraska Univ., Lincoln, NE (United States)
- Sponsoring Organization:
- DOE; USDOE, Washington, DC (United States)
- DOE Contract Number:
- FG02-91ER20053
- OSTI ID:
- 7024909
- Report Number(s):
- DOE/ER/20053-1; ON: DE93002236
- Country of Publication:
- United States
- Language:
- English
Similar Records
Mechanistic enzymology of CO dehydrogenase from Clostridium thermoaceticum. Progress report, March 25, 1993--March 24, 1994
Autotrophic growth: methylated carbon monoxide dehydrogenase as an intermediate of acetyl-CoA synthesis
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59 BASIC BIOLOGICAL SCIENCES
AMINO ACIDS
ANAEROBIC CONDITIONS
AROMATICS
AZAARENES
BACTERIA
BIOCHEMICAL REACTION KINETICS
BIOCONVERSION
BIOLOGICAL PATHWAYS
CARBON 13
CARBON COMPOUNDS
CARBON ISOTOPES
CARBON MONOXIDE
CARBON OXIDES
CARBOXYLIC ACIDS
CHALCOGENIDES
CLOSTRIDIUM
DOCUMENT TYPES
DRUGS
ENZYMES
EVEN-ODD NUCLEI
FOLIC ACID
HEMATINICS
HEMATOLOGIC AGENTS
HETEROCYCLIC COMPOUNDS
HYDROXY COMPOUNDS
ISOTOPE APPLICATIONS
ISOTOPES
KINETICS
LIGHT NUCLEI
MICROORGANISMS
NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXIDES
OXIDOREDUCTASES
OXYGEN COMPOUNDS
PROGRESS REPORT
PROTEINS
PTERIDINES
REACTION KINETICS
SPECIES DIVERSITY
STABLE ISOTOPES
TRACER TECHNIQUES
VITAMIN B GROUP
VITAMINS