Lundström-Ljung J, Vlamis-Gardikas A, Aslund F, Holmgren A
Medical Nobel Institute of Biochemistry, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden.
FEBS Lett. 1999 Jan 25;443(2):85-8. doi: 10.1016/s0014-5793(98)01698-6.
We have examined the activity of protein disulfide isomerase (PDI) and glutaredoxin (Grx) 1, 2 and 3 from Escherichia coli to catalyze the cleavage of glutathionylated ribonuclease A (RNase-SG) by 1 mM GSH to yield reduced RNase. Apparent Km values for RNase-SG were similar, 2-10 microM, for Grx 1, 3 and PDI but Grx I and Grx 3 showed 500-fold higher turnover numbers than PDI. The atypical Grx 2 also catalyzed deglutathionylation by GSH, but had higher Km and apparent turnover number values compared to the two classical Grx. Refolding of RNase in a glutathione redox buffer was catalyzed by PDI. However, it could be measured only after a characteristic lag phase that was shortened by all three E. coli Grxs in a concentration-dependent manner. A role of the glutaredoxin mechanism in the endoplasmic reticulum is suggested.
我们检测了来自大肠杆菌的蛋白质二硫键异构酶（PDI）和谷氧还蛋白（Grx）1、2及3催化1 mM谷胱甘肽（GSH）切割谷胱甘肽化核糖核酸酶A（RNase-SG）以产生还原型核糖核酸酶的活性。RNase-SG的表观米氏常数（Km）值对于Grx 1、3和PDI而言相似，为2 - 10 μM，但Grx 1和Grx 3的转换数比PDI高500倍。非典型的Grx 2也催化GSH介导的去谷胱甘肽化反应，但与两种经典的Grx相比，其Km值和表观转换数值更高。PDI催化核糖核酸酶在谷胱甘肽氧化还原缓冲液中的重折叠。然而，只有在一个特征性的延迟期后才能检测到，而大肠杆菌的所有三种Grx均以浓度依赖的方式缩短了该延迟期。这提示了谷氧还蛋白机制在内质网中的作用。
