Botnar Research Centre, University of Oxford, Oxford, UK.
Nanoscale. 2011 Sep 1;3(9):3805-11. doi: 10.1039/c1nr10502g. Epub 2011 Aug 12.
Due to its remarkable mechanical and biological properties, there is considerable interest in understanding, and replicating, spider silk's stress-processing mechanisms and structure-function relationships. Here, we investigate the role of water in the nanoscale mechanics of the different regions in the spider silk fibre, and their relative contributions to stress processing. We propose that the inner core region, rich in spidroin II, retains water due to its inherent disorder, thereby providing a mechanism to dissipate energy as it breaks a sacrificial amide-water bond and gains order under strain, forming a stronger amide-amide bond. The spidroin I-rich outer core is more ordered under ambient conditions and is inherently stiffer and stronger, yet does not on its own provide high toughness. The markedly different interactions of the two proteins with water, and their distribution across the fibre, produce a stiffness differential and provide a balance between stiffness, strength and toughness under ambient conditions. Under wet conditions, this balance is destroyed as the stiff outer core material reverts to the behaviour of the inner core.
由于其显著的机械和生物学特性，人们对理解和复制蜘蛛丝的应力处理机制和结构-功能关系非常感兴趣。在这里，我们研究了水在蜘蛛丝纤维不同区域的纳米力学中的作用，以及它们对应力处理的相对贡献。我们提出，富含丝氨酸 II 的内芯区域由于其固有无序性而保留水分，从而提供了一种机制，即在破坏一个牺牲的酰胺-水键并在应变下获得秩序时耗散能量，形成更强的酰胺-酰胺键。富含丝氨酸 I 的外芯在环境条件下更为有序，固有地更硬、更强，但本身并不能提供高韧性。两种蛋白质与水的明显不同相互作用，以及它们在纤维中的分布，产生了一个刚度差，在环境条件下为刚度、强度和韧性之间提供了平衡。在潮湿条件下，由于硬的外芯材料恢复到内芯的行为，这种平衡被破坏。
