Taraban Marc B, Feng Yue, Hammouda Boualem, Hyland Laura L, Yu Y Bruce
Fischell Department of Bioengineering, University of Maryland, College Park, USA.
Chem Mater. 2012 Jun 26;24(12):2299-2310. doi: 10.1021/cm300422q.
The origin and the effects of homochirality in the biological world continuously stimulate numerous hypotheses and much debate. This work attempts to look at the biohomochirality issue from a different angle-the mechanical properties of the bulk biomaterial and their relation to nanoscale structures. Using a pair of oppositely charged peptides that co-assemble into hydrogels, we systematically investigated the effect of chirality on the mechanical properties of these hydrogels through different combinations of syndiotactic and isotactic peptides. It was found that homochirality confers mechanical advantage, resulting in higher elastic modulus and strain yield value. Yet, heterochirality confer kinetic advantage, resulting in faster gelation. Structurally, both homochiral and heterochiral hydrogels are made of fibers interconnected by lappet-like webs, but the homochiral peptide fibers are thicker and denser. The result highlights the possible role of biohomochirality in the evolution and/or natural selection of biomaterials.
生物世界中同手性的起源和影响不断激发着众多假说和激烈争论。这项工作试图从一个不同的角度看待生物同手性问题——大块生物材料的力学性质及其与纳米级结构的关系。使用一对带相反电荷的肽共同组装成水凝胶，我们通过间同立构和全同立构肽的不同组合，系统地研究了手性对这些水凝胶力学性质的影响。研究发现，同手性赋予力学优势，导致更高的弹性模量和应变屈服值。然而，异手性赋予动力学优势，导致更快的凝胶化。在结构上，同手性和异手性水凝胶均由通过垂饰状网相互连接的纤维组成，但同手性肽纤维更粗且更致密。该结果突出了生物同手性在生物材料进化和/或自然选择中可能发挥的作用。
