The Conformation of a Soluble Wool Keratin Derivative

Abstract

The conformation of a low-sulphur soluble wool keratin derivative (SCMKA) has been studied by optical rotatory dispersion. On the assumption that the overall conformation consists of a mixture of a-helical and random-coil regions, this protein has a helical content of about 50% in aqueous solution at pH 9·1; this helical content does not vary with the degree of severity of the preparative procedure. The protein may be reversibly converted to the random-coil form by heating to 70°0, or by treatment with urea at concentrations exceeding 6r.r. An increase in pH to 12·5 causes very little change in conformation, such change as does occur being reversible. The maximum helical content which has been induced by solvents into the protein is about 62% in 2-chloroethanol. This probably represents the upper limit of the helical content of this protein as it occurs in the fibre. The changes in the conforma. tion of the protein which occur in several other solvents are briefly discussed.