Structure and folding of glucagon-like peptide-1-(7–36)-amide in aqueous trifluoroethanol studied by NMR spectroscopy |
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Authors: | Xiaoqing Chang Danielle Keller Søren Bjørn Jens J. Led |
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Affiliation: | 1. Department of Chemistry, University of Copenhagen, The H. C. Ørsted Institute, Universitetsparken 5, DK-2100 Copenhagen Ø, Denmark;2. Health Care Discovery, Novo Nordisk A/S, Novo Alle, DK-2880 Bagsværd, Denmark |
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Abstract: | The conformational changes of free, monomeric glucagon-like peptide-1-(7–36)-amide (GLP-1) in aqueous solution with increasing concentrations of 2,2,2-trifluoroethanol (TFE) were monitored by NMR spectroscopy. It was found that GLP-1 gradually assumes a stable, single-stranded helical structure in water solution when the TFE concentration is increased from 0 to 35% (v/v). No further structural changes were observed at higher TFE concentrations. The structure of GLP-1 in 35% TFE was determined from 292 distance restraints and 44 angle restraints by distance geometry, simulating annealing and restrained energy minimization. The helical structure extends from T7 to K28, with a less well-defined region around G16 and a disordered six-residue N-terminal domain. The folding process of GLP-1 from random coil (in water) to helix (in 35% TFE) is initiated by the formation of the C-terminal segment of the helix that is extended gradually towards the N-terminus of the peptide with increasing concentration of TFE. The exchange rates of the slow exchanging amide protons indicate that the C-terminal part of the helix is more stable than the N-terminal part. Copyright © 2001 John Wiley & Sons, Ltd. |
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Keywords: | NMR 1H NMR 13C NMR GLP-1 solution structure folding trifluoroethanol |
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