Grant Anise M, Krecker Michelle C, Gupta Maneesh K, Dennis Patrick B, Crosby Marquise G, Tsukruk Vladimir V
School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30305, United States.
Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433, United States.
ACS Biomater Sci Eng. 2020 Oct 12;6(10):5519-5526. doi: 10.1021/acsbiomaterials.0c00791. Epub 2020 Sep 14.
The Humboldt squid is one of the fiercest marine predators thanks in part to its sucker ring teeth that are biopolymer blends of a protein isoform family called suckerin with compression strength that rivals silkworm silk. Here, we focus on the popular suckerin-12 isoform to understand what makes the secondary structure of this biopolymer different in water and the potential role of diverse physical and chemical cross-linkings. By choosing a salt post-treatment, in accordance with the Hofmeister series, we achieved film stability with salt annealing that is comparable to chemical cross-links. By correlating the film morphology with the protein secondary structure changes, suckerin-12 films were shown to contract upon treatment with kosmotropic salts and exhibited increased stability in water. These changes are related to the rearrangement of suckerin-12 secondary structure from random coils and helices to β-sheets. Overall, understanding secondary structure changes caused by aqueous and ionic environments can be instructive for the tuning of the suckerin film sclerotization, its conversion to a tough biological material, and to ultimately produce the natural squid sucker ring teeth.
洪堡乌贼是最凶猛的海洋捕食者之一，部分原因在于其吸盘环齿，这些齿是一种名为suckerin的蛋白质异构体家族的生物聚合物混合物，其抗压强度可与蚕丝相媲美。在此，我们聚焦于广为人知的suckerin-12异构体，以了解是什么使得这种生物聚合物的二级结构在水中有所不同，以及各种物理和化学交联的潜在作用。通过根据霍夫迈斯特序列选择盐后处理，我们通过盐退火实现了与化学交联相当的薄膜稳定性。通过将薄膜形态与蛋白质二级结构变化相关联，结果表明，suckerin-12薄膜在用促溶盐处理时会收缩，并且在水中表现出更高的稳定性。这些变化与suckerin-12二级结构从无规卷曲和螺旋重排为β-折叠有关。总体而言，了解由水性和离子环境引起的二级结构变化，对于调节suckerin薄膜的硬化、将其转化为坚韧的生物材料以及最终制造天然乌贼吸盘环齿具有指导意义。
