Autotrophic growth: the methyl binding site of CO dehydrogenase in the synthesis of acetyl-CoA

Conference · Fri May 01 04:00:00 EDT 1987 · Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States)

OSTI ID:6024046

Pezacka, E; Wood, H G

A pathway in which CO or CO/sub 2/ and H/sub 2/ is used as a source of energy and carbon to synthesize acetyl-CoA is used for autotrophic growth of acetogenes, methanogens and some sulfate-reducing bacteria. All enzymes involved in this pathway have been purified from C. thermoaceticum. Five of them: CO dehydrogenase (CODH), corrinoid protein, methyltransferase, CODH disulfide reductase (SSRd) and ferredoxin catalyzed synthesis of acetyl-CoA from methyltetrahydrofolate, CO and CoA. CODH is a central enzyme catalyzing the condensation of CH/sub 3/, CO and CoA and per se it catalyzes a reversible exchange of CO with acetyl-CoA. Thus, CODH must have binding sites for CH/sub 3/, CO and CoA. They have succeeded in methylating ..beta.. subunits of CODH using /sup 14/CH/sub 3/I or /sup 14/CH-corrinoid protein, a native donor of the CH/sub 3/ group in synthesis of acetyl-CoA. With resulting (/sup 14/CH/sub 3/)CODH, only SSRd is required for synthesis of (/sup 14/C)acetyl-CoA from CO and CoA. The kinetic studies show that CH/sub 3/I is a competitive inhibitor for exchange reaction between CO and acetyl-CoA. Acetaldehyde and acetyl-CoA but not acetic acid and CoA protected CODH against methylation by CH/sub 3/I. Methyl group bound to CODH is very slowly removed by CO and CoA and acetyl-CoA accelerated this process. These data confirm that CH/sub 3/ group from CH/sub 3/I and CH/sub 3/-corrinoid protein is bound to the methyl binding site of CODH.

• Research Organization: Case Western Reserve Univ., Cleveland, OH
• OSTI ID: 6024046
• Report Number(s): CONF-870644-
• Conference Information: Journal Name: Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States) Journal Volume: 46:6
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
BACTERIA
BIOCHEMICAL REACTION KINETICS
BIOLOGICAL PATHWAYS
BIOSYNTHESIS
CARBON 14 COMPOUNDS
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON MONOXIDE
CARBON OXIDES
CHALCOGENIDES
COENZYMES
ELEMENTS
ENZYME INHIBITORS
ENZYMES
GROWTH
HYDROGEN
ISOTOPE APPLICATIONS
KINETICS
LABELLED COMPOUNDS
MEMBRANE PROTEINS
MICROORGANISMS
NONMETALS
ORGANIC COMPOUNDS
OXIDES
OXIDOREDUCTASES
OXYGEN COMPOUNDS
PROTEINS
REACTION KINETICS
RECEPTORS
SYNTHESIS
TRACER TECHNIQUES