Sriram R, Ali-Osman F
Department of Experimental Pediatrics, University of Texas M.D. Anderson Cancer Center, Houston 77030.
Biochem Mol Biol Int. 1993 Aug;30(6):1053-60.
gamma-Glutamylcysteine synthetase (EC 6.3.2.2.) the key regulatory enzyme in glutathione biosynthesis was purified from a human malignant astrocytoma cell line using a combination of ammonium sulfate fractionation, DE-52 cellulose chromatography and ATP-agarose affinity chromatography. The purified protein had a specific activity of 1725 units/mg protein, which represented an 86-fold purification and a 22% yield. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed two major subunits with apparent molecular sizes of 72 kDa and 32 kDa. The Km values for L-glutamate and L-alpha-aminobutyrate were 0.03 mM and 0.14 mM respectively. These molecular and catalytic properties of gamma-glutamylcysteine synthetase from astrocytoma cell line are similar, but not identical to those purified from rat kidney.
γ-谷氨酰半胱氨酸合成酶（EC 6.3.2.2.）是谷胱甘肽生物合成中的关键调节酶，采用硫酸铵分级分离、DE-52纤维素层析和ATP-琼脂糖亲和层析相结合的方法，从人恶性星形细胞瘤细胞系中纯化得到该酶。纯化后的蛋白质比活性为1725单位/毫克蛋白质，纯化倍数为86倍，产率为22%。十二烷基硫酸钠-聚丙烯酰胺凝胶电泳显示有两个主要亚基，表观分子大小分别为72 kDa和32 kDa。L-谷氨酸和L-α-氨基丁酸的Km值分别为0.03 mM和0.14 mM。来自星形细胞瘤细胞系的γ-谷氨酰半胱氨酸合成酶的这些分子和催化特性与从大鼠肾脏中纯化得到的相似，但并不完全相同。
