Microfibrillar Proteins of Wool: Partial Specific Volumes and Molecular Weights in Denaturing Solvents

Abstract

The molecular weights of the reduced and S-carboxymethylated microfibrillar protein components of wool have been investigated by sedimentation equilibrium in 6 M guanidine hydrochloride and by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The microfibrillar proteins have molecular weights of 57000 (component 5), 58000 (component 7c); 50000 (component 8c-l) with a range of values for the other component 8 polypeptide chains of 45 000--50 000. The proteins migrate anomalously in polyacrylamide gels in the presence of sodium dodecyl sulfate as seen from a comparison of the free mobilities and retardation coefficients of standard proteins with those of the wool proteins. More reliable molecular weights were obtained by plotting the retardation coefficients against molecular weights (Ferguson plot). The partial specific volumes of the microfibrillar proteins have been measured in dilute aqueous buffer solutions, 8 M urea and 6 M guanidine hydrochloride. The values are compared to those calculated from the amino acid compositions.