Solid State Conformational Transitions In Peptides Modeling B. <i>Mori</i> Fibroin

Abstract Fibrous proteins are molecules whose secondary structures are their dominant motifs due to their highly repetitive amino acid sequences. Most fibrous proteins have physiological roles as protective, connective or structural materials. Among the fibrous proteins, silks tend to have blocky structures, with crystallizable and amorphous blocks comprised of short, highly repetitive amino acid sequences. In addition, the high glycine content of silks allows them greater conformational variability than most proteins, thus Bombyx morisilk fibroin is typically polymorphic. The ability of silk fibroin to adopt multiple conformations and crystal structures makes it difficult to obtain corroborating data using multiple characterization techniques. Differences in sample preparation to accommodate different techniques can also affect the resulting sample structure. Reproducible sample preparation was achieved for IR and TEM experiments by rubbing the dried IR sample with a carbon substrate TEM grid to pick up tiny flakes of solidified peptide.