Determination of the amide I Raman tensor for the antiparallel β-sheet: application to silkworm and spider silks

Authors

  • Masamichi Tsuboi,

    1. Division of Cell Biology and Biophysics, School of Biological Sciences, University of Missouri-Kansas City, 5100 Rockhill Road, Kansas City, Missouri 64110, USA
    2. College of Science and Engineering, Iwaki-Meisei University, Iwaki, Fukushima 970-8551, Japan
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  • Yoshiko Kubo,

    1. JASCO, 2967-5 Ishikawa-cho, Hachioji, Tokyo 192-8537, Japan
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  • Kiso Akahane,

    1. Department of Chemistry, Faculty of Science, Josai University, Sakado, Saitama 350-0002, Japan
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  • James M. Benevides,

    1. Division of Cell Biology and Biophysics, School of Biological Sciences, University of Missouri-Kansas City, 5100 Rockhill Road, Kansas City, Missouri 64110, USA
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  • George J. Thomas Jr

    Corresponding author
    1. Division of Cell Biology and Biophysics, School of Biological Sciences, University of Missouri-Kansas City, 5100 Rockhill Road, Kansas City, Missouri 64110, USA
    • Division of Cell Biology and Biophysics, School of Biological Sciences, University of Missouri-Kansas City, 5100 Rockhill Road, Kansas City, Missouri 64110, USA.
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  • Presented as part of a commemorative issue for Wolfgang Kiefer on the occasion of his 65th birthday.

Abstract

The amide I Raman tensor corresponding to the antiparallel β-sheet structure in proteins has been determined by polarized Raman microspectroscopy of fowl feather rachis using polarized Raman spectra excited in the near-infrared (785 nm). For a Raman tensor principal axis system (XYZ), in which X is perpendicular to the plane of the pleated β-sheet, Y is in the plane of the sheet and perpendicular to the direction of the polypeptide chain, and Z is parallel to the direction of the polypeptide chain, the principal tensor components (αXX, αYY, αZZ) are found to satisfy the following relationships: R1 ≡ αXXZZ = 0.32 and R2 ≡ αYYZZ = 3.48. With this Raman tensor determination, we show that semiquantitative estimates of the total antiparallel β-sheet content in β-rich proteins can be extracted from polarized Raman intensity measurements on the amide I marker of the β-sheet occurring near 1664 cm−1. We demonstrate this approach for the β-rich silk proteins of the silkworm and spider. Copyright © 2006 John Wiley & Sons, Ltd.

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