Phosphoenolpyruvate carboxylation and aspartate synthesis in Acetobacter suboxydans.
Dialyzed extracts of Acetobacter suboxydans ATCC 621 catalyze (14)CO(2) assimilation in the presence of phosphoenolpyruvate and a divalent cation. The formation of (14)C-oxalacetate was demonstrated and found not to be dependent upon the presence of orthophosphate or diphosphonucleotides. Oxalacetate synthesis was stimulated by orthophosphate and inhibited by aspartate. All attempts to demonstrate a reversible carboxylation mechanism have failed. (14)C-aspartate was synthesized when phosphoenolpyruvate, H(14)Co(3) (-), pyridoxal phosphate, and glutamate were added to dialyzed extracts. Chromatographic and spectrophotometric analyses and chemical degradation further demonstrate the presence of a reversible aspartate aminotransferase. The function of oxalacetate synthesis in a bacterium that reportedly lacks an operative tricarboxylic acid cycle is discussed.
D000091:Acetobacter / Q000201:enzymology / Q000378:metabolism*; D001219:Aspartate Aminotransferases; D001224:Aspartic Acid / Q000096:biosynthesis*; D002245:Carbon Dioxide / Q000378:metabolism*; D002247:Carbon Isotopes; D002474:Cell-Free System; D002854:Chromatography, Paper; D010071:Oxaloacetates / Q000096:biosynthesis; D010659:Phenylhydrazines / Q000032:analysis; D011773:Pyruvates / Q000378:metabolism*; D013053:Spectrophotometry
D002247:Carbon Isotopes; D010071:Oxaloacetates; D010659:Phenylhydrazines; D011773:Pyruvates; D002245:Carbon Dioxide; D001224:Aspartic Acid; D001219:Aspartate Aminotransferases