Analysis of spider silk in native and supercontracted states using Raman spectroscopy

Well-defined, fluorescence-free Raman spectra were obtained from native as well as treated (supercontracted) major ampullate dragline silks reeled from four very different spiders: Araneus diadematus, Nephila edulis, Latrodectus mactans and Euprosthenops sp. Conformational sensitive regions were assigned in the spectra. Compared to the silk of the silkworm Bombyx mori, all spider silks showed less beta-sheet and more random coil and/or alpha-helix material. Polarized spectra suggested that the molecular chains of the spider silk were aligned parallel to the axis of the fibre. The differences in the mechanical properties between the native and supercontracted silks were attributed to variations in beta-sheet content. The mechanism of contraction of spider silks in solvents was correlated to conformational changes in the supermolecular structure. (C) 1999 Elsevier Science Ltd. All rights reserved.