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Catabolic and anabolic enzyme activities and energetics of acetone metabolism of the sulfate-reducing bacterium Desulfococcus biacutus.
| Content Provider | Semantic Scholar |
|---|---|
| Author | Janssen, Peter H. Schnik, B. |
| Copyright Year | 1995 |
| Abstract | Acetone degradation by cell suspensions of Desulfococcus biacutus was CO2 dependent, indicating initiation by a carboxylation reaction, while degradation of 3-hydroxybutyrate was not CO2 dependent. Growth on 3-hydroxybutyrate resulted in acetate accumulation in the medium at a ratio of 1 mol of acetate per mol of substrate degraded. In acetone-grown cultures no coenzyme A (CoA) transferase or CoA ligase appeared to be involved in acetone metabolism, and no acetate accumulated in the medium, suggesting that the carboxylation of acetone and activation to acetoacetyl-CoA may occur without the formation of a free intermediate. Catabolism of 3-hydroxybutyrate occurred after activation by CoA transfer from acetyl-CoA, followed by oxidation to acetoacetyl-CoA. In both acetone-grown cells and 3-hydroxybutyrate-grown cells, acetoacetyl-CoA was thioyltically cleaved to two acetyl-CoA residues and further metabolized through the carbon monoxide dehydrogenase pathway. Comparison of the growth yields on acetone and 3-hydroxybutyrate suggested an additional energy requirement in the catabolism of acetone. This is postulated to be the carboxylation reaction (delta G(o)' for the carboxylation of acetone to acetoacetate, +17.1 kJ.mol-1). At the intracellular acyl-CoA concentrations measured, the net free energy change of acetone carboxylation and catabolism to two acetyl-CoA residues would be close to 0 kJ.mol of acetone-1, if one mol of ATP was invested. In the absence of an energy-utilizing step in this catabolic pathway, the predicted intracellular acetoacetyl-CoA concentration would be 10(13) times lower than that measured. Thus, acetone catabolism to two acetyl-CoA residues must be accompanied by the utilization of teh energetic equivalent of (at lease) one ATP molecule. Measurement of enzyme activities suggested that assimilation of acetyl-CoA occurred through a modified citric acid cycle in which isocitrate was cleaved to succinate and glyoxylate. Malate synthase, condensing glyoxylate and acetyl-CoA, acted as an anaplerotic enzyme. Carboxylation of pyruvate of phosphoenolpyruvate could not be detected. |
| Starting Page | 692 |
| Ending Page | 697 |
| Page Count | 6 |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | https://kops.uni-konstanz.de/bitstream/handle/123456789/6869/Catabolic_and_Anabolic_Enzyme_1995.pdf?isAllowed=y&sequence=1 |
| Alternate Webpage(s) | http://jb.asm.org/content/177/2/277.full.pdf |
| Alternate Webpage(s) | http://kops.uni-konstanz.de/bitstream/handle/123456789/6869/Catabolic_and_Anabolic_Enzyme_1995.pdf?sequence=1 |
| PubMed reference number | 7814315v1 |
| Volume Number | 177 |
| Issue Number | 2 |
| Journal | Journal of bacteriology |
| Language | English |
| Access Restriction | Open |
| Subject Keyword | 3-Hydroxyacyl CoA Dehydrogenases 3-Hydroxybutyrate Acetoacetates Acetyl-CoA C-Acetyltransferase Acetyl-CoA C-Acyltransferase Acyl Coenzyme A Adenosine Triphosphate Anabolic steroids Carbon Dioxide Citric Acid Cycle Cleaved cell Coenzymes DUOXA1 gene Desulfococcus oleovorans Ephrin Type-B Receptor 1, human Glyoxylates Isocitrates Ligase Malate Synthase Metabolic Process, Cellular Mole, unit of measurement Pyruvates Succinates Suspensions Transcription Initiation Transferase acetate biosynthetic process from carbon monoxide acetone catabolic process acetone metabolic process free energy gamma-delta T-Cell Receptor oxidation |
| Content Type | Text |
| Resource Type | Article |
