Sedimentation and diffusion studies on a derivative of wool keratin

Abstract A derivative of wool keratin dissolved in a strong solution of urea was examined in the ultracentrifuge and by diffusion methods. The solution was polydisperse, yielding a single broad peak in the ultracentrifuge. Approximate molecular constants were calculated to be s 1.93, D20m = 1.9 × 107, M = 84,000, f/f0 = 3.8. The molecule is very asymmetrical, which is in accord with the fiber‐forming properties of the derivative. On further reduction the molecular weight falls to ca. 8000 and the molecule shortens. It is suggested that the fully reduced solution (M.W. = 8000) is that of the primary polypeptides of wool keratin and that the longer and larger molecules (M.W. = 80,000) are formed by the combination of the primary chains effected by disulfide bridges.