Purification, characterization and identification of tryptophan aminotransferase from rat brain.
Tryptophan aminotransferase was purified from rat brain extracts. The purified enzyme had an isoelectric point at pH 6.2 and a pH optimum near 8.0. On electrophoresis the enzyme migrated to the anode. The enzyme was active with oxaloacetate or 2-oxoglutarate as amino acceptor but not with pyruvate, and utilized various L-amino acids as amino donors. With 2-oxoglutarate, the order of effectiveness of the L-amino acids was aspartate >> 5-hydroxytryptophan > tryptophan > tyrosine > phenylalanine. Aminotransferase activity of the enzyme towards tryptophan was inhibited by L-glutamate. Sucrose density gradient centrifugation gave a molecular weight of approx. 55,000. The enzyme was present in both the cytosol and synaptosomal cytosol, but not in the mitochondria. The isoelectric focusing profile of tryptophan: oxaloacetate aminotransferase activity was identical with that of L-aspartate: 2-oxoglutarate aminotransferase (EC 2.6.1.1) activity, with both subcellular fractions. On the basis of these data, it is suggested that the enzyme is identical with the cytosol aspartate: 2-oxoglutarate aminotransferase.
Minatogawa
Y
Y
Department of Biochemistry, Wakayama Medical College, Wakayama 640, Japan.
Noguchi
T
T
Kido
R
R
D000818:Animals; D001219:Aspartate Aminotransferases / Q000032:analysis / Q000302:isolation & purification; D001921:Brain / Q000201:enzymology*; D001923:Brain Chemistry; D002848:Chromatography, DEAE-Cellulose; D002850:Chromatography, Gel; D004591:Electrophoresis, Polyacrylamide Gel; D004789:Enzyme Activation / Q000502:physiology; D006863:Hydrogen-Ion Concentration; D007525:Isoelectric Focusing; D008297:Male; D008970:Molecular Weight; D051381:Rats; D011919:Rats, Inbred Strains; D013347:Subcellular Fractions / Q000201:enzymology; D013379:Substrate Specificity; D000637:Transaminases / Q000032:analysis / Q000302:isolation & purification*; D051279:Tryptophan Transaminase
D000637:Transaminases; D001219:Aspartate Aminotransferases; D051279:Tryptophan Transaminase