Denaturation in Regenerated Protein Fibres

Abstract

IN a discussion on the possibility of producing a regenerated keratin fibre, Mercer1 claims to have retained the α-form of the molecule in wool reconstituted from solution. This is a matter of some interest, as the yarns produced by Dr. R. L. Wormell2 and myself show no evidence of the α-keratin structure even in orientated fibres. During the past few months, highly orientated specimens of casein yarn have been made3 which may throw some light on Mercer's results, especially with reference to the type of solution from which fibres are drawn containing an α-keratin phase. Fig. 1 is an X-ray photograph of a Ferretti-type casein fibre which shows little or no obvious orientation by X-rays. Fig. 2 is an X-ray photograph of highly orientated casein which is, in the main, made up of reflexions from a two-phase system. First there is the X-ray photograph of a normal β-protein type of fibre comprising an axial repeat of 3·25 A., a backbone spacing of 4·65 A., and a side-chain spacing of approximately 10·5 A. Superimposed on this diagram, however, there is a strong polar arc of 4·65 A., which is most probably indicative of a protein phase containing a crystalline cross β-configuration of the molecule.