Lindberg M O, Tångrot J, Otzen D E, Dolgikh D A, Finkelstein A V, Oliveberg M
Department of Biochemistry, Umeå University, Umeå, S-901 87, Sweden.
J Mol Biol. 2001 Dec 7;314(4):891-900. doi: 10.1006/jmbi.2001.5186.
To examine the influence of contact order and stability on the refolding rate constant for two-state proteins, we have analysed the folding kinetics of the small beta-alpha-beta protein S6 and two of its circular permutants with relative contact orders of 0.19, 0.15 and 0.12. Data reveal a small but significant increase of the refolding rate constant (log k(f)) with decreasing contact order. At the same time, the decreased contact order is correlated to losses in global stability and alterations of the folding nucleus. When the differences in stability are accounted for by addition of Na2SO4 or by comparison of the folding kinetics at the transition mid-point, the dependence between log k(f) and contact order becomes stronger and follows the general correlation for two-state proteins. The observation emphasizes the combined action of topology and stability in controlling the rate constant of protein folding.
为了研究接触顺序和稳定性对两态蛋白质重折叠速率常数的影响，我们分析了小的β-α-β蛋白S6及其两个相对接触顺序分别为0.19、0.15和0.12的环形置换变体的折叠动力学。数据显示，随着接触顺序的降低，重折叠速率常数（log k(f)）有小幅但显著的增加。同时，接触顺序的降低与整体稳定性的损失以及折叠核的改变相关。当通过添加Na2SO4或通过比较转变中点的折叠动力学来考虑稳定性差异时，log k(f)与接触顺序之间的依赖性变得更强，并遵循两态蛋白质的一般相关性。该观察结果强调了拓扑结构和稳定性在控制蛋白质折叠速率常数方面的联合作用。
