The purification and properties of L-histidine--2-oxoglutarate aminotransferase from Pseudomonas testosteroni.
1. Inducible L-histidine--2-oxoglutarate aminotransferase was purified some 170-fold from extracts of Pseudomonas testosteroni. 2. The preparation showed only one major component after electrophoresis on polyacrylamide gels, though additional minor bands were observed when samples concentrated on a DEAE-cellulose column were used. 3. The molecular weight of the enzyme was found to be approx. 70000 by chromatography on Sephadex G-200. 4. The purification scheme produced enzyme that was inactive in the absence of pyridoxal 5'-phosphate. 5. The equilibrium constant for the reaction L-histidine+2-oxoglutarate equilibrium  imidazolylpyruvate+L-glutamate was 0.49. 6. The reaction mechanism was Ping Pong. 7. The enzyme was shown to have only low activity towards aromatic amino acids and was highly specific for 2-oxoglutarate.
D002848:Chromatography, DEAE-Cellulose; D002850:Chromatography, Gel; D002854:Chromatography, Paper; D004591:Electrophoresis, Polyacrylamide Gel; D004790:Enzyme Induction; D005971:Glutamates; D006639:Histidine; D006863:Hydrogen-Ion Concentration; D007093:Imidazoles; D007656:Ketoglutaric Acids; D007700:Kinetics; D008970:Molecular Weight; D011549:Pseudomonas / Q000201:enzymology*; D011732:Pyridoxal Phosphate; D000637:Transaminases / Q000037:antagonists & inhibitors / Q000302:isolation & purification*
D005971:Glutamates; D007093:Imidazoles; D007656:Ketoglutaric Acids; D006639:Histidine; D011732:Pyridoxal Phosphate; D000637:Transaminases