Determining beta-sheet stability by Fourier transform infrared difference spectra
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Updated: Aug 12, 2026

Thermodynamics of Membrane Protein Folding Measured by Fluorescence Spectroscopy
Published on: April 28, 2011
1Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104, USA.
Abstract:
We describe here a new method for determining the conformational stability of antiparallel beta-sheets. Due to coupling between the transition dipoles, beta-sheet conformations typically exhibit a characteristic high-frequency amide I component centered at approximately 1680 cm(-1). Using one beta-sheet protein and two small beta-hairpins, we demonstrate that this high-frequency component, which is fairly narrow (approximately 8-10 cm(-1)), can be quantitatively resolved and used in thermal stability determination. Compared with the commonly used CD and fluorescence techniques, this ir method offers advantages. Since the area of this high-frequency component is only proportional to the folded population, it eliminates the need for a priori information of the folded and unfolded baselines encountered in other methods. Thus, it is applicable to a variety of beta-sheet systems.
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