Department of Textile Technology and ‡Department of Chemistry, Indian Institute of Technology Delhi , Hauz Khas, New Delhi 110016, India.
Biomacromolecules. 2015 Dec 14;16(12):3936-44. doi: 10.1021/acs.biomac.5b01258. Epub 2015 Nov 24.
Controlling the mechanism of self-assembly in proteins has emerged as a potent tool for various biomedical applications. Silk fibroin self-assembly consists of gradual conformational transition from random coil to β-sheet structure. In this work we elucidated the intermediate secondary conformation in the presence of Ca(2+) ions during fibroin self-assembly. The interaction of fibroin and calcium ions resulted in a predominantly α-helical intermediate conformation, which was maintained to certain extent even in the final conformation as illustrated by circular dichroism and attenuated total reflectance-Fourier transform infrared spectroscopy. Further, to elucidate the mechanism behind this interaction molecular modeling of the N-terminal region of fibroin with Ca(2+) ions was performed. Negatively charged glutamate and aspartate amino acids play a key role in the electrostatic interaction with positively charged calcium ions. Therefore, insights about modulation of self-assembly mechanism of fibroin could potentially be utilized to develop silk-based biomaterials consisting of the desired secondary conformation.
控制蛋白质的自组装机制已成为各种生物医学应用的有力工具。丝素蛋白的自组装包括从无规卷曲到β-折叠结构的逐渐构象转变。在这项工作中，我们阐明了丝素蛋白自组装过程中存在 Ca(2+) 离子时的中间二级构象。丝素蛋白与钙离子的相互作用导致了主要的α-螺旋中间构象，即使在最终构象中也保持了一定程度的稳定，如圆二色性和衰减全反射-傅里叶变换红外光谱所示。此外，为了阐明这种相互作用的机制，我们对丝素蛋白 N 端区域与 Ca(2+) 离子进行了分子建模。带负电荷的谷氨酸和天冬氨酸氨基酸在与带正电荷的钙离子的静电相互作用中起着关键作用。因此，对丝素蛋白自组装机制的调节的深入了解可能会被用来开发包含所需二级构象的基于丝素的生物材料。
