Kuszewski J, Clore G M, Gronenborn A M
Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892-0520.
Protein Sci. 1994 Nov;3(11):1945-52. doi: 10.1002/pro.5560031106.
The folding of the small (56 residues) highly stable B1 immunoglobulin binding domain (GB1) of streptococcal protein G has been investigated by quenched-flow deuterium-hydrogen exchange. This system represents a paradigm for the study of protein folding because it exhibits no complicating features superimposed upon the intrinsic properties of the polypeptide chain. Collapse to a semicompact state exhibiting partial order, reflected in protection factors for ND-NH exchange up to 10-fold higher than that expected for a random coil, occurs within the dead time (< or = 1 ms) of the quenched flow apparatus. This is followed by the formation of the fully native state, as monitored by the fractional proton occupancy of 26 backbone amide groups spread throughout the protein, in a single rapid concerted step with a half-life of 5.2 ms at 5 degrees C.
通过淬灭流动氘-氢交换研究了链球菌蛋白G的小（56个残基）高度稳定的B1免疫球蛋白结合结构域（GB1）的折叠。该系统代表了蛋白质折叠研究的一个范例，因为它没有表现出叠加在多肽链固有特性上的复杂特征。在淬灭流动装置的死时间（≤1毫秒）内，会折叠成一种呈现部分有序的半紧密状态，这体现在ND-NH交换的保护因子比随机卷曲预期的高10倍。随后形成完全天然状态，这通过分布在整个蛋白质中的26个主链酰胺基团的质子占有率分数来监测，在5℃下以5.2毫秒的半衰期在一个单一的快速协同步骤中完成。
