Nishikimi M, Kobayashi J, Yagi K
Institute of Applied Biochemistry, Yagi Memorial Park, Gifu, Japan.
Biochem Mol Biol Int. 1994 May;33(2):313-9.
L-Gulono-gamma-lactone oxidase, an enzyme functioning in L-ascorbic acid biosynthesis in higher animals, possesses a covalently-bound FAD as the prosthetic group. Catalytically-active enzyme was expressed in silkworm cells by a recombinant baculovirus encoding rat L-gulono-gamma-lactone oxidase. When recombinant enzyme was expressed under riboflavin-deficient conditions, most of it was found to be the apoprotein, as evidenced by an increase in enzymic activity upon addition of FAD to the assay mixture. Interestingly, the observed enzymic activity is thought to have been provoked by a noncovalent interaction between FAD and the apoprotein, since the covalent attachment of FAD was not demonstrated by a fluorometric gel-scanning experiment.
L-古洛糖酸-γ-内酯氧化酶是高等动物体内参与L-抗坏血酸生物合成的一种酶，它以共价结合的黄素腺嘌呤二核苷酸（FAD）作为辅基。通过编码大鼠L-古洛糖酸-γ-内酯氧化酶的重组杆状病毒在蚕细胞中表达了具有催化活性的该酶。当重组酶在核黄素缺乏的条件下表达时，发现大部分是脱辅基蛋白，这通过向测定混合物中添加FAD后酶活性增加得到证明。有趣的是，观察到的酶活性被认为是由FAD与脱辅基蛋白之间的非共价相互作用引发的，因为荧光凝胶扫描实验未证明FAD的共价连接。
