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Molecular dynamics simulation of transmembrane polypeptide orientational fluctuations.
David J Goodyear1, Simon Sharpe, Chris W M Grant
1Department of Physics and Physical Oceanography, Memorial University of Newfoundland, St. John's, Newfoundland A1B 3X7, Canada.
Biophysical Journal
|October 19, 2004
Summary
Molecular dynamics simulations reveal that transmembrane polypeptides exhibit preferred azimuthal orientation within lipid bilayers, influenced by surface interactions. This behavior aligns with experimental findings from 2H NMR studies.
Area of Science:
- Biophysics
- Computational Biology
- Membrane Protein Dynamics
Background:
- Transmembrane polypeptides exhibit complex reorientation within lipid bilayers.
- 2H NMR studies suggest preferred azimuthal orientation for helical polypeptides.
Purpose of the Study:
- Investigate interactions influencing transmembrane polypeptide orientation.
- Simulate a model lysine-terminated polypeptide in a POPC bilayer.
Main Methods:
- Molecular dynamics simulations.
- Utilized a system of 64 POPC molecules and one alpha-helical polypeptide.
- Performed simulations at 55°C and 1 atm pressure.
Main Results:
- Simulated alanine methyl group orientations were inequivalent, matching 2H NMR data.
- Peptide orientation about the helix axis tended towards experimentally suggested values.
- Helix tilt varied significantly during simulations.
Conclusions:
- Bilayer surface interactions constrain polypeptide reorientation about the helix axis.
- Simulations provide insights into the dynamics of transmembrane polypeptides.
- Findings are consistent with experimental 2H NMR observations.