Department of Materials Science and Engineering, University of Delaware, Newark, DE, USA; NIST Center for Neutron Research (NCNR), National Institute of Standards & Technology (NIST), Gaithersburg, MD, USA.
Department of Chemistry, University of Pennsylvania, Philadelphia, PA, USA.
J Colloid Interface Sci. 2022 Jan 15;606(Pt 2):1974-1982. doi: 10.1016/j.jcis.2021.09.184. Epub 2021 Oct 1.
The use of isotropic potential models of simple colloids for describing complex protein-protein interactions is a topic of ongoing debate in the biophysical community. This contention stems from the unavailability of synthetic protein-like model particles that are amenable to systematic experimental characterization. In this article, we test the utility of colloidal theory to capture the solution structure, interactions and dynamics of novel globular protein-mimicking, computationally designed peptide assemblies called bundlemers that are programmable model systems at the intersection of colloids and proteins. Small-angle neutron scattering (SANS) measurements of semi-dilute bundlemer solutions in low and high ionic strength solution indicate that bundlemers interact locally via repulsive interactions that can be described by a screened repulsive potential. We also present neutron spin echo (NSE) spectroscopy results that show high-Q freely-diffusive dynamics of bundlemers. Importantly, formation of clusters due to short-range attractive, inter-bundlemer interactions is observed in SANS even at dilute bundlemer concentrations, which is indicative of the complexity of the bundlemer charged surface. The similarities and differences between bundlemers and simple colloidal as well as complex protein-protein interactions is discussed in detail.
使用各向同性势能模型来描述复杂的蛋白质-蛋白质相互作用，这在生物物理界是一个持续争论的话题。这种争议源于缺乏可进行系统实验表征的合成类似蛋白质的模型粒子。在本文中，我们测试胶体理论在捕获新型球状蛋白模拟、计算设计的肽组装体（称为束状分子）的溶液结构、相互作用和动力学方面的适用性，这些组装体是胶体和蛋白质交叉领域的可编程模型系统。在低离子强度和高离子强度溶液中，半稀束状分子溶液的小角中子散射（SANS）测量表明，束状分子通过可以用屏蔽排斥势描述的排斥相互作用在局部相互作用。我们还呈现了中子自旋回波（NSE）光谱结果，表明束状分子具有高 Q 值的自由扩散动力学。重要的是，即使在束状分子浓度稀的情况下，SANS 中也观察到由于短程吸引力引起的束状分子间的簇形成，这表明束状分子带电表面的复杂性。本文详细讨论了束状分子与简单胶体以及复杂蛋白质-蛋白质相互作用之间的异同。
