Carbon-13 NMR Studies of Keratin Intermediate Filament of Human Hair

    February 1998 in “ Polymer ”
    Naoki Nishikawa, Yoshiaki Tanizawa, Shoichi Tanaka, Yasunobu Horiguchi, Hitomi Matsuno, Tetsuo Asakura
    TLDR Human hair keratin has a 40% α-helix structure that changes to a random coil in 8 M urea.
    The study investigated the 13C n.m.r. spectra of the low sulfur fraction in S-(carboxymethyl) keratin (SCMKA), representing the hard keratin intermediate filament in human hair, in aqueous solution. It was found that SCMKA exhibited a 40% α-helix structure in aqueous solution, which transformed into a random coil structure in 8 M urea, similar to the high sulfur fraction (SCMKB) in aqueous solution. The spectra indicated that amino acid residues such as Thr, Ser, Pro, and Gly in the N- and C-terminal domains had high mobility due to their random coil structure, while residues like Leu, Ile, Glu, Arg, and Lys in the rod domain showed no peaks, suggesting restricted motion due to a coiled-coil structure.
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