Structural Studies Of Recombinant And Natural Spider Silk Proteins Studied By Nuclear Magnetic Resonance; Insights For The Spinning Process

Abstract

Spider silk is a biomaterial with astonishing properties that compete with the best synthetic man made materials such as Kevlar. For example, the dragline fiber is as strong as steel and the total energy to break is 6 times higher than Kevlar. These mechanical properties confer to the spider silk several potential medical and military applications such as bullet-proof vests, stitches, ligaments and tendons from tissue engineering. Nexia biotechnologies Inc. were able to make fibers from recombinant proteins but without achieving the same mechanical properties as the natural spider dragline.The secondary structure that the two proteins adopt is known to be very important for the mechanical properties of silk. So our work is to study the structure-function relationship of the proteins by solution and solid-state nuclear magnetic resonance (NMR) spectroscopy and dynamic light scattering (DLS). One of the goals of our research project is therefore to study the proteins in solution, at the beginning of the spinning process and at the fiber state and to understand the conditions in which the structural transition is done. More specifically, we are investigating the structure of the two proteins, the aggregation processes and the level of compaction as a function of temperature, pH and salt concentration by solution NMR spectroscopy and DLS. In the solid-state, we are investigating the gland content in situ under MAS to compare between the recombinant, the natural and the in situ behavior. The comparison of the results gives insights on the role of the physicochemical modifications in the spiders' natural spinning process and supports the idea of using recombinant spider silk proteins as the source of raw material for industrial production of spider silk.