Sastre J, Siegrist S, Bulle F, Asensi M, Baik J H, Pawlak A, Guellaën G
U-99 INSERM, Hôpital Henri Mondor, Créteil, France.
Biochem Mol Biol Int. 1996 Apr;38(4):801-11.
The understanding of the structure and function of gamma-glutamyl transpeptidase (GGT) has been hindered by the difficulty of obtaining large quantities of functional enzyme. A recombinant baculovirus, encoding the human hepatoma cell (Hep G2) GGT, was easily purified using a histochemical procedure to reveal GGT activity. Infected insect cells synthesized a large amount of enzymatically active GGT representing up to 10% of the total cell extract protein. The GGT specific activity of the infected cells was 13 units per mg of protein which is the highest GGT expression level reported to date, 260-times more than in Hep G2 cells. The recombinant protein displayed an apparent molecular mass (M(r), 58,000 for the heavy subunit), immunoreactivity and catalytic features similar to those of the native protein. The high-level expression of functional GGT should provide an excellent tool to further study the structure-function relationships of the protein.
由于难以获得大量有功能的γ-谷氨酰转肽酶（GGT），对其结构和功能的认识受到了阻碍。一种编码人肝癌细胞（Hep G2）GGT的重组杆状病毒，通过组织化学方法很容易纯化以显示GGT活性。被感染的昆虫细胞合成了大量具有酶活性的GGT，其含量高达总细胞提取物蛋白的10%。被感染细胞的GGT比活性为每毫克蛋白13个单位，这是迄今为止报道的最高GGT表达水平，比Hep G2细胞中的表达水平高260倍。重组蛋白显示出明显的分子量（重亚基的M(r)为58,000）、免疫反应性和与天然蛋白相似的催化特性。功能性GGT的高水平表达应为进一步研究该蛋白的结构-功能关系提供一个极好的工具。
