Laboratory for Atomistic and Molecular Mechanics, Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue Room 1-235A&B, Cambridge, Massachusetts 02139, USA.
Phys Rev Lett. 2010 May 14;104(19):198304. doi: 10.1103/PhysRevLett.104.198304. Epub 2010 May 12.
The alpha-helix to beta-sheet transition (α-β transition) is a universal deformation mechanism in alpha-helix rich protein materials such as wool, hair, hoof, and cellular proteins. Through a combination of molecular and theoretical modeling, we examine the behavior of alpha-helical coiled-coil proteins with varying lengths under stretch. We find that the occurrence of the α-β transition is controlled by the length of constituting alpha-helical proteins. In the asymptotic limit, short proteins with less than 26 amino acids or 3.8 nm length reveal interprotein sliding, whereas proteins with greater lengths feature an α-β transition, leading to a significant increase in the protein's stiffness, strength, and energy dissipation capacity at large deformation. Our study elucidates the fundamental physics of this mechanism and explains why the α-β transition typically occurs in protein filaments with long alpha-helical domains.
α-螺旋到β-折叠的转变（α-β 转变）是富含α-螺旋的蛋白质材料（如羊毛、头发、蹄和细胞蛋白）中的一种普遍变形机制。通过分子和理论建模的结合，我们研究了在拉伸下具有不同长度的α-螺旋卷曲螺旋蛋白的行为。我们发现，α-β 转变的发生受组成α-螺旋蛋白长度的控制。在渐近极限下，长度小于 26 个氨基酸或 3.8nm 的短蛋白质会发生蛋白间滑动，而较长的蛋白质则会发生 α-β 转变，导致蛋白质在大变形时的刚度、强度和能量耗散能力显著增加。我们的研究阐明了这一机制的基础物理学，并解释了为什么α-β 转变通常发生在具有长α-螺旋结构域的蛋白质纤维中。
