Singh Vijay R, Lapidus Lisa J
J Phys Chem B. 2008 Oct 23;112(42):13172-6. doi: 10.1021/jp805636p. Epub 2008 Sep 26.
We have used the method of Trp/Cys contact quenching to measure the rate of contact formation in polyglutamine and find it to be a very stiff peptide. Separation of observed rates into reaction-limited and diffusion-limited rates show that the reaction-limited rates increase (rather than decrease) slightly with length between 4 and 16 amino acids. Using Szabo, Schulten, and Schulten theory, we have modeled the results with a wormlike chain with excluded volume and find the persistence length to be about 13.0 A, much longer than has been observed for other random peptides and unfolded proteins. The preferred extended conformation of polyglutamine could account for a propensity for expanded glutamine stretches to unfold the Huntington's protein and the high propensity to aggregate from a disordered monomer.
我们采用色氨酸/半胱氨酸接触猝灭法来测量聚谷氨酰胺中接触形成的速率，并发现它是一种非常刚性的肽。将观察到的速率分离为反应限制速率和扩散限制速率表明，反应限制速率在4至16个氨基酸之间的长度上略有增加（而非减少）。使用萨博、舒尔滕和舒尔滕理论，我们用具有排除体积的蠕虫状链对结果进行了建模，发现持久长度约为13.0埃，比其他随机肽和未折叠蛋白所观察到的要长得多。聚谷氨酰胺偏好的伸展构象可能解释了谷氨酰胺延伸段易于使亨廷顿蛋白展开以及从无序单体聚集的高倾向性。
