Varley P, Gronenborn A M, Christensen H, Wingfield P T, Pain R H, Clore G M
Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health (NIH), Bethesda, MD 20892.
Science. 1993 May 21;260(5111):1110-3. doi: 10.1126/science.8493553.
The folding of the all-beta sheet protein, interleukin-1 beta, was studied with nuclear magnetic resonance (NMR) spectroscopy, circular dichroism, and fluorescence. Ninety percent of the beta structure present in the native protein, as monitored by far-ultraviolet circular dichroism, was attained within 25 milliseconds, correlating with the first kinetic phase determined by tryptophan and 1-anilinonaphthalene-8-sulfonate fluorescence. In contrast, formation of stable native secondary structure, as measured by quenched-flow deuterium-hydrogen exchange experiments, began after only 1 second. Results from the NMR experiments indicated the formation of at least two intermediates with half-lives of 0.7 to 1.5 and 15 to 25 seconds. The final stabilization of the secondary structure, however, occurs on a time scale much greater than 25 seconds. These results differ from previous results on mixed alpha helix-beta sheet proteins in which both the alpha helices and beta sheets were stabilized very rapidly (less than 10 to 20 milliseconds).
利用核磁共振（NMR）光谱、圆二色性和荧光对全β折叠蛋白白细胞介素-1β的折叠进行了研究。通过远紫外圆二色性监测，天然蛋白中90%的β结构在25毫秒内形成，这与由色氨酸和1-苯胺基萘-8-磺酸盐荧光测定的第一个动力学阶段相关。相比之下，通过淬灭流动氘-氢交换实验测定，稳定的天然二级结构仅在1秒后开始形成。NMR实验结果表明形成了至少两种中间体，半衰期分别为0.7至1.5秒和15至25秒。然而，二级结构的最终稳定发生在远大于25秒的时间尺度上。这些结果与之前关于混合α螺旋-β折叠蛋白的结果不同，在混合α螺旋-β折叠蛋白中，α螺旋和β折叠都非常迅速地（小于10至20毫秒）得到稳定。
