Structure-function relationships in synthetic spider silk fibers made from chimeric proteins

To further our knowledge on structure function relationships in spider silk proteins, several chimeric spider silk proteins with basic repeat sequences mixing different ratios of one of the two different Flagelliform silk like elastic motifs ([GPGGX GPGGX]n with X=A/A or Y/S) and the dragline silk crystalline forming/strength motif ([GPSGPGS(A)₈) from Masp2) were engineered. All of these chimeric silk proteins were produced recombinantly in E. coli bacteria and used to generate fibers that were subjected to post spinning modifications using alcohols and water to improve their mechanical properties. For each synthetic fiber type and at each step of the processing, structural (NMR, XRD, Raman Spectroscopy, morphological (SEM) and mechanical data were collected. In all cases, we find that water treatment was overall beneficial and had a platicization effect on the silk fibers.