Asparagine and glutamine metabolism in Rhodopseudomonas acidophila.

Rhodopseudomonas acidophila strain 7050 achieved balanced growth when provided with either asparagine or glutamine as nitrogen source. Under these growth conditions R. acidophila synthesized a mixed amidase which exhibited similar activity (223-422 nmol/min·mg protein) against either nitrogen source. Determination of the free intracellular amino acid pools show that deamidation of asparagine and glutamine resulted in elevated levels of both aspartate and glutamate. Cell-free extracts of R. acidophila showed significant aminotransferase activity, particulary glutamine-oxaloacetate aminotransferase (89.7-209.3 nmol/min·mg protein), glycine oxaloacetate aminotransferase (135-227 nmol/min ·mg protein), alanine glyoxylate aminotransferase (66.3-163.2 nmol/min·mg protein) and serineglyoxylate aminotransferase (57.1-68.4 nmol/min ·mg protein). Short term labelling experiments using C-glyoxylate show that glycine plays an important role in amino nitrogen transfer in R. acidophila and that the enzymes for the metabolism of glyoxylate via glycine, serine and hydroxypyruvate were present in cell-free extracts. These data confirm that R. acidophila can satisfy all its' nitrogen requirements by transamination. [ABSTRACT FROM AUTHOR]