Okuno E, Minatogawa Y, Kido R
Biochim Biophys Acta. 1982 Mar 15;715(1):97-104. doi: 10.1016/0304-4165(82)90054-x.
Alanine-glyoxylate aminotransferase and 2-aminobutyrate aminotransferase were co-purified from rat kidney to a single protein (about 500-fold purified from the homogenate). The activity ratios of alanine-glyoxylate aminotransferase to 2-aminobutyrate aminotransferase were constant during co-purification steps suggesting the 2-aminobutyrate aminotransferase activity was catalysed by only alanine-glyoxylate aminotransferase. The molecular weight of the enzyme was estimated to be approx. 213 000, 220 000 and 236 000 by analytical ultracentrifugation, Sephadex G-150 gel filtration and sucrose density gradient centrifugation, respectively. From the polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulphate, the enzyme consisted of four apparently similar subunits having a molecular weight of approx. 56 000. The enzyme was almost specific to L-alanine and L-2-aminobutyrate as amino donor and to glyoxylate, pyruvate and 2-oxobutyrate as amino acceptor. The enzyme was identified with rat liver alanine-glyoxylate aminotransferase isoenzyme 2 but not with rat liver alanine-glyoxylate aminotransferase isoenzyme 1 from Ouchterlony double diffusion analysis. Absorption spectra and some kinetic properties of the enzyme were clarified.
丙氨酸-乙醛酸氨基转移酶和2-氨基丁酸氨基转移酶从大鼠肾脏中共纯化得到单一蛋白质（相对于匀浆纯化了约500倍）。在共纯化步骤中，丙氨酸-乙醛酸氨基转移酶与2-氨基丁酸氨基转移酶的活性比保持恒定，这表明2-氨基丁酸氨基转移酶活性仅由丙氨酸-乙醛酸氨基转移酶催化。通过分析超速离心、葡聚糖G-150凝胶过滤和蔗糖密度梯度离心法分别估计该酶的分子量约为213000、220000和236000。在十二烷基硫酸钠存在下进行的聚丙烯酰胺凝胶电泳显示，该酶由四个明显相似的亚基组成，分子量约为56000。该酶几乎特异性地以L-丙氨酸和L-2-氨基丁酸作为氨基供体，以乙醛酸、丙酮酸和2-氧代丁酸作为氨基受体。通过双向免疫扩散分析鉴定该酶为大鼠肝脏丙氨酸-乙醛酸氨基转移酶同工酶2，而非大鼠肝脏丙氨酸-乙醛酸氨基转移酶同工酶1。阐明了该酶的吸收光谱和一些动力学性质。
