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PURIFICATION, CHARACTERIZATION AND IDENTIFICATION OF TRYPTOPHAN AMINOTRANSFERASE FROM RAT BRAIN
Author(s) -
Minatogawa Y.,
Noguchi T.,
Kido R.
Publication year - 1976
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1976.tb00314.x
Subject(s) - identification (biology) , tryptophan , biochemistry , biology , computational biology , chemistry , ecology , amino acid
— 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 isoelectrk 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.