Pharmaceutical Sciences Research Center, Shiraz University of Medical Sciences, Shiraz 7193371, Iran.
School of Dentistry, Marquette University, Milwaukee, Wisconsin 53233-2186, United States.
J Phys Chem B. 2020 Mar 5;124(9):1637-1652. doi: 10.1021/acs.jpcb.9b10980. Epub 2020 Feb 21.
Insulin, which is a small protein hormone consisting of 51 amino acids, rapidly fibrillates under stressogenic conditions. This biotechnological/medical problematic reaction quickly accelerates in the presence of some particles, while there are several other particles that slow down the kinetic process. To address the unexplored demand of the particles that modulate protein fibrillation, we have synthesized two amino-based particles and a chitosan-coated mesoporous silica particle (MS-NH, MS-3NH, and MS-chitosan) to investigate insulin fibrillation. While these particles were fairly similar in size, they are differ in their net positive charge and surface hydrophobicity. To monitor the exact role of the hydrophobic interaction between the protein and MS-chitosan during the fibrillation, we have also co- and preincubated insulin with cholesterol and the particles under stressogenic conditions. The results indicate that MS-NH and MS-3NH, due to their high positive charges and lack of surface hydrophobicity, repel the positively charged unfolded insulins at pH 2.0. Moreover, MS-chitosan with 25% surface hydrophobicity stacks partially unfolded insulins to its surface and induces some α-helix to β-sheet structural transitions to the protein. Consequently, both amino- and chitosan-based particles slow down the kinetics of the fibrillation. We also showed that cholesterol can structurally participate in insulin fibril architecture as a hydrophobic bridge, and extraction of this molecule from the preformed fibrils may disrupt the fibril structure.
胰岛素是一种由 51 个氨基酸组成的小蛋白激素，在应激条件下迅速形成纤维。这种生物技术/医学上的问题反应在存在某些颗粒时会迅速加速，而有些颗粒则会减缓动力学过程。为了解决调节蛋白质纤维形成的颗粒的未知需求，我们合成了两种基于氨基酸的颗粒和一种壳聚糖涂层的介孔硅颗粒（MS-NH、MS-3NH 和 MS-壳聚糖）来研究胰岛素纤维形成。虽然这些颗粒在大小上相当相似，但它们的净正电荷和表面疏水性不同。为了监测在纤维形成过程中蛋白质与 MS-壳聚糖之间的疏水相互作用的确切作用，我们还在应激条件下将胆固醇和颗粒与胰岛素共孵育和预孵育。结果表明，由于 MS-NH 和 MS-3NH 带高正电荷且表面疏水性低，它们在 pH 2.0 时排斥带正电荷的未折叠胰岛素。此外，表面疏水性为 25%的 MS-壳聚糖部分堆积未折叠的胰岛素到其表面，并诱导蛋白质发生一些α-螺旋到β-折叠结构转变。因此，基于氨基酸和壳聚糖的颗粒都减缓了纤维形成的动力学过程。我们还表明，胆固醇可以作为疏水桥结构参与胰岛素纤维结构，并且从预形成的纤维中提取这种分子可能会破坏纤维结构。
