Okuno E, Du F, Ishikawa T, Tsujimoto M, Nakamura M, Schwarcz R, Kido R
Wakayama Medical College, Department of Biochemistry, Japan.
Brain Res. 1990 Nov 26;534(1-2):37-44. doi: 10.1016/0006-8993(90)90109-o.
Kynurenine-pyruvate aminotransferase (KPT), the enzyme responsible for the biosynthesis of the endogenous excitatory amino acid receptor antagonist kynurenic acid, was purified to homogeneity from rat kidney, as judged by polyacrylamide and sodium dodecyl sulfate electrophoresis. The protein appeared to consist of 2 identical subunits of approximately 48 kDa. Kinetic analysis showed Km values of 2.8 mM (kynurenine) and 3.8 mM (pyruvate), respectively. KPT was also partially purified from rat brain. Kidney and brain KPT were found to be identical when analyzed by a spectrum of biochemical, physico-chemical and, after production of anti-kidney KPT antibodies, immunological methods. Partially purified anti-KPT antiserum was used for first immunohistochemical studies, which revealed the presence of the enzyme in astrocyte-like cells throughout the brain. Less frequently, KPT was also found in discretely arranged neurons. The availability of pure KPT and specific anti-KPT antibodies can be expected to be of value for the further examination of the neurobiology of kynurenic acid.
犬尿氨酸-丙酮酸转氨酶（KPT）是负责内源性兴奋性氨基酸受体拮抗剂犬尿喹啉酸生物合成的酶，通过聚丙烯酰胺和十二烷基硫酸钠电泳判断，该酶已从大鼠肾脏中纯化至同质。该蛋白质似乎由两个约48 kDa的相同亚基组成。动力学分析表明，其对犬尿氨酸和丙酮酸的Km值分别为2.8 mM和3.8 mM。KPT也从大鼠大脑中部分纯化。通过一系列生化、物理化学方法以及在产生抗肾脏KPT抗体后采用免疫方法分析发现，肾脏和大脑中的KPT是相同的。部分纯化的抗KPT抗血清用于首次免疫组织化学研究，结果显示该酶存在于全脑的星形胶质样细胞中。较少见的是，在离散排列的神经元中也发现了KPT。预计纯KPT和特异性抗KPT抗体的可得性对于进一步研究犬尿喹啉酸的神经生物学具有重要价值。
