Kynurenine–glyoxylate aminotransferase, alanine–glyoxylate aminotransferase and serine–pyruvate aminotransferase were co-purified and crystallized as yellow cubes from human liver particulate fraction. The crystalline enzyme was homogeneous by the criteria of electrophoresis, isoelectric focusing, gel filtration, sucrose-density-gradient centrifugation and analytical ultracentrifugation. The molecular weight of the enzyme was calculated as approx. 90000, 89000 and 99000 by the use of gel filtration, analytical ultracentrifugation and sucrose-density-gradient centrifugation respectively, with two identical subunits. The enzyme has a s20,w value of 5.23S, an isoelectric point of 8.3 and a pH optimum between 9.0 and 9.5. The enzyme solution showed absorption maxima at 280 and 420nm. The enzyme catalysed transamination between several l-amino acids and pyruvate or glyoxylate. The order of effectiveness of amino acids was alanine>serine>glutamine>glutamate>methionine>kynurenine = phenylalanine = asparagine>valine>histidine>lysine>leucine>isoleucine>arginine>tyrosine = threonine>aspartate, with glyoxylate as amino acceptor. The enzyme was active with glyoxylate, oxaloacetate, hydroxypyruvate, pyruvate, 4-methylthio-2-oxobutyrate and 2-oxobutyrate, but showed little activity with phenylpyruvate, 2-oxoglutarate and 2-oxoadipate, with kynurenine as amino donor. Kynurenine–glyoxylate aminotransferase activity was competitively inhibited by the addition of l-alanine or l-serine. From these results we conclude that kynurenine–glyoxylate aminotransferase, alanine–glyoxylate aminotransferase and serine–pyruvate aminotransferase activities of human liver are catalysed by a single protein. Kinetic parameters for the kynurenine–glyoxylate aminotransferase, alanine–glyoxylate aminotransferase, serine–pyruvate aminotransferase and alanine–hydroxypyruvate aminotransferase reactions of the enzyme are presented.
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September 1980
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Research Article|
September 01 1980
Crystallization and characterization of human liver kynurenine–glyoxylate aminotransferase. Identity with alanine–glyoxylate aminotransferase and serine–pyruvate aminotransferase
Etsuo Okuno;
Etsuo Okuno
1Department of Biochemistry, Wakayama Medical College, Wakayama 640, Japan
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Yohsuke Minatogawa;
Yohsuke Minatogawa
1Department of Biochemistry, Wakayama Medical College, Wakayama 640, Japan
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Masayuki Nakamura;
Masayuki Nakamura
1Department of Biochemistry, Wakayama Medical College, Wakayama 640, Japan
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Naoki Kamoda;
Naoki Kamoda
1Department of Biochemistry, Wakayama Medical College, Wakayama 640, Japan
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Junko Nakanishi;
Junko Nakanishi
1Department of Biochemistry, Wakayama Medical College, Wakayama 640, Japan
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Minoru Makino;
Minoru Makino
1Department of Biochemistry, Wakayama Medical College, Wakayama 640, Japan
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Ryo Kido
Ryo Kido
1Department of Biochemistry, Wakayama Medical College, Wakayama 640, Japan
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Biochem J (1980) 189 (3): 581–590.
Citation
Etsuo Okuno, Yohsuke Minatogawa, Masayuki Nakamura, Naoki Kamoda, Junko Nakanishi, Minoru Makino, Ryo Kido; Crystallization and characterization of human liver kynurenine–glyoxylate aminotransferase. Identity with alanine–glyoxylate aminotransferase and serine–pyruvate aminotransferase. Biochem J 1 September 1980; 189 (3): 581–590. doi: https://doi.org/10.1042/bj1890581
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