Assay and properties of acetone carboxylase, a novel enzyme involved in acetone-dependent growth and CO2 fixation in Rhodobacter capsulatus and other photosynthetic and denitrifying bacteria

Article Abstract:

The kinetics of acetone carboxylase activity in Rhodobacter capsulatus was analyzed by utilizing a novel assay for acetone-dependent CO2 fixation in cell-free extracts. Analysis of acetone carboxylase activity in cell-free extracts of Rhodobacter capsulatus based on a novel assay for acetone carboxylation indicated the biotin-independent nature of the novel carboxylase. Furthermore, the acetyl-CoA acted as an activator or component of the acetone carboxylase-mediated reaction mechanism.

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Acetyl-CoA-dependent pyruvate carboxylase from the photosynthetic bacterium Rhodobacter capsulatus: rapid and efficient purification using dye-ligand affinity chromatography

Article Abstract:

A rapid dye-ligand affinity chromatography method is used in the purification of acetyl-CoA-dependent pyruvate carboxylase (PC) from the photosynthetic bacterium Rhodobacter capsulatus. In this procedure, the PC activity is eluted from the dye column with a low concentration of acetyl-CoA. The enzyme, generated in 75% yield, has a specific activity of 40 U per (mg protein) and a molecular mass of 140000 Da. Acetyl-CoA activates the enzyme and 2-oxoglutarate inhibits it.

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Evidence for the presence of the reductive pentose phosphate cycle in a filamentous anoxygenic photosynthetic bacterium, Oscillochloris trichoides strain DG-6

Article Abstract:

Research was conducted to demonstrate the operation of the reductive pentose phosphate cycle in Oscillochloris trichoides strain DG-6. Key enzymes of the cycle-rublose-1,5-biphosphate carboxylase/oxygenase and phosphoribulokinase were observed in cell extracts. The addition of cyanide led to complete inhibition of 14CO2 assimilation in O. trichoides DG-6 cels. Results indicate that a functional reductive pentose phosphate cycle is present in O. trichoides DG-6 activity.

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