Okuno E, Nishikawa T, Nakamura M
Wakayayama Medical College, Wakayama, Japan.
Adv Exp Med Biol. 1996;398:455-64. doi: 10.1007/978-1-4613-0381-7_71.
Kynurenine-2-oxoglutarate aminotransferase (kynurenine specific, designated here KAT-II) and kynurenine pyruvate aminotransferase (designated here KAT-I) activities were detected in the kidney using 2 microM kynurenine. The major activities were performed by KAT-II and the contributi-n of KAT-I is about 1/15. KAT-I activity was detected in all organs tested. The liver showed the highest KAT-I activity, however, the highest activity of glutamine transaminase-K (GTK) was detected in the kidney. KAT-I activity was well corresponded with GTK activity in all organs except liver. KAT-I or GTK activity of crude extract didn't inhibited by addition of glutamine either kynurenine. KAT-I or GTK activity of purified preparation, however, inhibited strongly addition of glutamine either kynurenine. KAT-I and GTK showed different pH optimum profile, but purified and crude preparation of those were similar. Phenylpyruvate or 2-oxo-4-methiolbutyrate reduced the inhibition of purified KAT-I activity by glutamine using 2 microM kynurenine. Phenylpyruvate changed the Km value for kynurenine and Vmax, suggesting conformational change of the enzyme.
使用2微摩尔犬尿氨酸检测了肾脏中犬尿氨酸-2-氧代戊二酸氨基转移酶（犬尿氨酸特异性，在此处指定为KAT-II）和犬尿氨酸丙酮酸氨基转移酶（在此处指定为KAT-I）的活性。主要活性由KAT-II执行，KAT-I的贡献约为1/15。在所有测试器官中均检测到KAT-I活性。肝脏显示出最高的KAT-I活性，然而，谷氨酰胺转氨酶-K（GTK）的最高活性在肾脏中检测到。除肝脏外，所有器官中KAT-I活性与GTK活性均良好对应。粗提物的KAT-I或GTK活性不受添加谷氨酰胺或犬尿氨酸的抑制。然而，纯化制剂的KAT-I或GTK活性受到添加谷氨酰胺或犬尿氨酸的强烈抑制。KAT-I和GTK显示出不同的最适pH曲线，但它们的纯化制剂和粗提物相似。使用2微摩尔犬尿氨酸时，苯丙酮酸或2-氧代-4-甲硫基丁酸降低了谷氨酰胺对纯化的KAT-I活性抑制作用。苯丙酮酸改变了犬尿氨酸的Km值和Vmax，表明该酶发生了构象变化。
