Glutamine Transaminase Isozymeの精製と性質

概要

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The author has found glutamine-ketoacids transaminase (GKT) activity in both the soluble and the mitochondrial fractions of rat liver and kidney. The liver enzymes were purified about 130 fold and GPT activity was not observed in the purified enzymes. The soluble GKT (GKTs) could be separated from the mitochondrial GKT (GKTM) by using zone electrophoresis and DEAE-cellulose column chromatography. The Km value of GKTM for glyoxylic acid was higher than that of GKTs. From these evidences described above, the GKT are considered to be isozymes each other which are localized in different compartment in the cells. The both purified isozymes had the highest specificity for glyoxylic acid. Some other ketoacids also could be amino acceptors for GKT, though they had a lower affinity than that of glyoxylic acid. They reacted with GKT as the following order : pyruvic acid > phenylpypuvic acid > α-ketobutyric acid > oxalacetic acid. The Km values of GKTs and GKTM for glutamine were 2.0×10^<-3>M and 2.2×10^<-3>M, respectively, and those for glyoxylic acid were 3.8× 10^<-3>M and 6.8×10^<-3>M, respectively, These GKT were strongly inhibited by isonicotinic acid hydrazide or hydroxylamine. Pyridoxal phosphate was partially resoluted from holo-GKT by dialysing against 10^<-3>M hydroxylamine solution and the resoluted GKT recovered its activity by the addition of pyridoxal phosphate.
日本ビタミン学会の論文
1967-03-25