Zhang N, Li J, Wang C
National Laboratory of Biomacromolecules, Institute of Biophysics, Academia Sinica, Beijing, China.
J Protein Chem. 2000 Oct;19(7):569-74. doi: 10.1023/a:1007146217946.
Simultaneous presence of two chaperones, GroEL and protein disulfide isomerase (PDI), assists the reactivation of denatured D-glyceraldehyde-3-phosphate dehydrogenase (GAPDH) in an additive way. Delayed addition of chaperones to the refolding solution after dilution of denatured GAPDH indicates an interaction with intermediates formed mainly in the first 5 min for PDI and formed within a longer time period for GroEL-ATP. The above indicate that the two chaperones interact with different folding intermediates of GAPDH. After delayed addition of one chaperone to the refolding mixture containing the other at 4 degrees C, GroEL binds with all GAPDH intermediates dissociated from PDI, and PDI interacts with the intermediates released from GroEL during the first 10-20 min. It is suggested that the GAPDH folding intermediates released from the chaperone-bound complex are still partially folded so as to be rebound by the other chaperone. The above results clearly support the network model of GroEL and PDI.
伴侣蛋白GroEL和蛋白质二硫键异构酶（PDI）同时存在时，会以累加的方式协助变性的D-甘油醛-3-磷酸脱氢酶（GAPDH）重新激活。在变性的GAPDH稀释后，将伴侣蛋白延迟添加到复性溶液中，这表明PDI主要在最初5分钟内与形成的中间体相互作用，而GroEL-ATP则在更长的时间段内与形成的中间体相互作用。上述结果表明，这两种伴侣蛋白与GAPDH的不同折叠中间体相互作用。在4℃下，将一种伴侣蛋白延迟添加到含有另一种伴侣蛋白的复性混合物中后，GroEL会与所有从PDI解离的GAPDH中间体结合，而PDI则在最初10 - 20分钟内与从GroEL释放的中间体相互作用。这表明从伴侣蛋白结合复合物中释放的GAPDH折叠中间体仍处于部分折叠状态，从而能够被另一种伴侣蛋白重新结合。上述结果清楚地支持了GroEL和PDI的网络模型。
