Thormann Esben, Hansen Per Lyngs, Simonsen Adam Cohen, Mouritsen Ole G
MEMPHYS, Physics Department, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark.
Colloids Surf B Biointerfaces. 2006 Dec 1;53(2):149-56. doi: 10.1016/j.colsurfb.2006.08.015. Epub 2006 Aug 30.
Dynamic force spectroscopy makes it possible to measure the breaking of single molecular bonds or the unfolding of single proteins subjected to a time-dependent pulling force. The force needed to break a single bond or to unfold a domain in a protein depends critically on the time dependence of the applied force. In this way the elastic response couples to the unbinding force. We have performed an experimental and theoretical examination of this coupling by studying the well-known biotin-streptavidin bond in systems incorporating two common types of linkers. In the first case biotin is linked by bovine serum albumin (BSA) and it is observed that this linker has a linear elastic response. More surprisingly we find that its force constant varies significantly between repeated force curves. It is demonstrated that by sorting the force curves according to the force constant of the linker we can improve the data analysis and obtain a better agreement between experimental data and theory. In the second case biotin is linked by poly(ethylene glycol) (PEG), which has a soft nonlinear elastic response. A numerical calculation of the unbinding statistics for the polymer system agrees quantitatively with experiments. It demonstrates a clear decrease in unbinding forces resulting from the polymer linker.
动态力谱能够测量单分子键的断裂或在随时间变化的拉力作用下单蛋白质的展开。断裂单键或使蛋白质中的一个结构域展开所需的力关键取决于所施加力的时间依赖性。通过这种方式，弹性响应与解离力相互耦合。我们通过研究包含两种常见类型连接子的系统中著名的生物素 - 链霉亲和素键，对这种耦合进行了实验和理论研究。在第一种情况下，生物素通过牛血清白蛋白（BSA）连接，观察到这种连接子具有线性弹性响应。更令人惊讶的是，我们发现其力常数在重复的力曲线之间有显著变化。结果表明，通过根据连接子的力常数对力曲线进行分类，我们可以改进数据分析，并使实验数据与理论之间达成更好的一致性。在第二种情况下，生物素通过聚乙二醇（PEG）连接，PEG具有软非线性弹性响应。对聚合物系统解离统计的数值计算与实验定量相符。它表明聚合物连接子导致解离力明显降低。
