Secondary structure of peptides mimicking the Gly-rich regions of major ampullate spidroin protein 1 and 2

Abstract

Spider dragline silk has highly desirable material properties, possessing high extensibility, strength, and biocompatibility. Before it is spun, the constituent proteins are stored in a concentrated dope that is void of fibrils. To investigate the structural properties of the amorphous fiber regions in the dope, computer simulations were performed on model peptides representing the N. clavipes Gly-rich regions. Analysis of the secondary structure found predominantly turns, bends and coils; a small 31-helical population decreased with increasing concentration. Interestingly, the population of 31-helices saw a large increase in octanol. These results indicate that the unusual 31-helical secondary structure of the Gly-rich region of the fiber is a consequence of the spinning process, and that the low dielectric environment of the fiber may assist in favoring this structure.