NMR studies of the aggregation of glucagon-like peptide-1: formation of a symmetric helical dimer

FEBS Lett. 2002 Mar 27;515(1-3):165-70. doi: 10.1016/s0014-5793(02)02466-3.

Abstract

Nuclear magnetic resonance (NMR) spectroscopy reveals that higher-order aggregates of glucagon-like peptide-1-(7-36)-amide (GLP-1) in pure water at pH 2.5 are disrupted by 35% 2,2,2-trifluoroethanol (TFE), and form a stable and highly symmetric helical self-aggregate. NMR spectra show that the helical structure is identical to that formed by monomeric GLP-1 under the same experimental conditions [Chang et al., Magn. Reson. Chem. 37 (2001) 477-483; Protein Data Bank at RCSB code: 1D0R], while amide proton exchange rates reveal a dramatic increase of the stability of the helices of the self-aggregate. Pulsed-field gradient NMR diffusion experiments show that the TFE-induced helical self-aggregate is a dimer. The experimental data and model calculations indicate that the dimer is a parallel coiled coil, with a few hydrophobic residues on the surface that may cause aggregation in pure water. The results suggest that the coiled coil dimer is an intermediate state towards the formation of higher aggregates, e.g. fibrils.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Diffusion
  • Dimerization
  • Glucagon / chemistry*
  • Glucagon-Like Peptide 1
  • Hydrogen Bonding / drug effects
  • Magnetic Resonance Spectroscopy*
  • Models, Molecular
  • Molecular Sequence Data
  • Peptide Fragments / chemistry*
  • Protein Binding / drug effects
  • Protein Binding / physiology
  • Protein Conformation / drug effects
  • Protein Precursors / chemistry*
  • Protein Structure, Secondary / drug effects
  • Protein Structure, Secondary / physiology
  • Trifluoroethanol / chemistry
  • Trifluoroethanol / pharmacology
  • Water / chemistry

Substances

  • Peptide Fragments
  • Protein Precursors
  • Water
  • Trifluoroethanol
  • Glucagon-Like Peptide 1
  • Glucagon