Structural Studies on the Microfibrillar Proteins of Wool: Characterization of the a-Helix-Rich Particle Produced by Chymotryptic Digestion

Abstract

The .alpha.-helix-rich particle produced by chymotryptic digestion of the reduced and alkylated microfibrillar proteins of wool was characterized by physicochemical methods. The preparations were homogeneous with respect to size and the particle MW was 50,200 .+-. 2000. Hydrodynamic methods indicated a length of .apprx. 20 nm for the particle. The properties of the particle, derived from 2 methods of isolation of the microfibrillar proteins, were identical and were independent of the type of wool used. Consideration of the MW in denaturing solvents and from cross-linking experiments with dimethyl suberimidate led to a proposed particle structure consisting of a pair of double-stranded .alpha.-helices in a 4-chain structure.