The Silk I and Lamella Structures of (Ala-Gly)15 as the Model of Bombyx mori Silk Fibroin Studied with Solid State NMR

Abstract

The specific structures, Silk I and Lamella, observed in the sequence model peptides, (Ala-Gly)(n) of Bombyx mori silk fibroin, could be determined by several C-13 solid state NMR techniques coupled with C-13 selective labeling of the peptides. The former is the silk fibroin structure before spinning that is a key structure in order to clarify the mechanism of formation of the silk fiber with exceptional strength and toughness from the aqueous solution in silkworm. The latter is a unique structure related with Silk II as referred to the silk fibroin structure after spinning and useful in molecular design the biomaterials with silk. The C-13 solid state NMR coupled with C-13/N-15 stable isotope labeling is very useful to clarify these specific structures appeared in the fibrous protein and therefore the process of the determination is described in detail.