Mechanical unfolding of alpha- and beta-helical protein motifs

Abstract

Alpha-helices and beta-sheets are the two most common secondary motifs in proteins. Beta-helices combine features of both motifs to perform a wide variety of functions. Possessing a larger width to height ratio, beta-helices resist unfolding by rotating to larger angles with respect to the loading direction, resulting in hydrogen bonds being ruptured in shear or out of plane peeling rather than in-plane peeling. This allows beta-helices to achieve greater energy dissipation per residue than alpha-helices.