Kalita C C, Kerman J D, Strecker H J
Biochim Biophys Acta. 1976 May 13;429(3):780-97. doi: 10.1016/0005-2744(76)90325-9.
Ornithine-oxo-acid aminotransferase (EC 2.6.1.13) from rat kidney was prepared as a single homogeneous protein as judged by polyacrylamide gel electrophoresis, ultracentrifuge analysis and double diffusion precipitin test. Content of pyridoxal phosphate, light absorption spectra, circular dicroism spectra, Km values, inhibitors, and electrophoretic mobilities of the proteins after reactions with group modifying reagents were similar for the ornithine-oxo-acid aminotransferases of rat kidney and liver. Rates of reaction with group modifying reagents, stabilities to storage at -15 degrees C, and stabilities to temperatures above 55 degrees C differed significantly for the two enzymes. The liver enzyme contained two more cysteine residues than the kidney enzyme as determined by three different methods. Heating the liver enzyme at 66-67 degrees C at pH 5.9 for 1 h decreased the thiol groups titratable by 5,5'-dithio-bis(2-nitrobenzoic acid) (Nbs2). Uncer the same conditions titratable thiol groups of the kidney enzyme were not decreased. Amino acid analysis revealed probably significant differences in tyrosine and isoleucine content in addition to cysteine. It was concluded that the primary structures of ornithine-oxo-acid aminotransferases of rat liver and kidney are not fully identical.
通过聚丙烯酰胺凝胶电泳、超速离心分析和双向扩散沉淀试验判断，从大鼠肾脏中制备的鸟氨酸-氧代酸转氨酶（EC 2.6.1.13）为单一纯蛋白。大鼠肾脏和肝脏的鸟氨酸-氧代酸转氨酶与基团修饰试剂反应后，其磷酸吡哆醛含量、光吸收光谱、圆二色光谱、米氏常数、抑制剂以及蛋白质的电泳迁移率均相似。两种酶与基团修饰试剂的反应速率、在-15℃下储存的稳定性以及在55℃以上温度下的稳定性存在显著差异。通过三种不同方法测定，肝脏中的该酶比肾脏中的酶多两个半胱氨酸残基。在pH 5.9条件下，将肝脏中的酶在66 - 67℃加热1小时，可滴定的巯基（用5,5'-二硫代双（2-硝基苯甲酸）（Nbs2）滴定）减少。在相同条件下，肾脏中的酶可滴定的巯基并未减少。氨基酸分析表明，除了半胱氨酸外，酪氨酸和异亮氨酸含量可能也存在显著差异。得出的结论是，大鼠肝脏和肾脏的鸟氨酸-氧代酸转氨酶的一级结构并不完全相同。
