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Updated: Aug 13, 2026
Realistic Membrane Modeling Using Complex Lipid Mixtures in Simulation Studies
Published on: September 1, 2023
Molecular dynamics simulations of model trans-membrane peptides in lipid bilayers: a systematic investigation of
Senthil K Kandasamy1, Ronald G Larson
1Chemical Engineering Department, University of Michigan, Ann Arbor, Michigan, USA.
Abstract:
Hydrophobic mismatch, which is the difference between the hydrophobic length of trans-membrane segments of a protein and the hydrophobic width of the surrounding lipid bilayer, is known to play a role in membrane protein function. We have performed molecular dynamics simulations of trans-membrane KALP peptides (sequence: GKK(LA)nLKKA) in phospholipid bilayers to investigate hydrophobic mismatch alleviation mechanisms. By varying systematically the length of the peptide (KALP15, KALP19, KALP23, KALP27, and KALP31) and the lipid hydrophobic length (DLPC, DMPC, and DPPC), a wide range of mismatch conditions were studied. Simulations of durations of 50-200 ns show that under positive mismatch, the system alleviates the mismatch predominantly by tilting the peptide and to a smaller extent by increased lipid ordering in the immediate vicinity of the peptide. Under negative mismatch, alleviation takes place by a combination of local bilayer bending and the snorkeling of the lysine residues of the peptide. Simulations performed at a higher peptide/lipid molar ratio (1:25) reveal slower dynamics of both the peptide and lipid relative to those at a lower peptide/lipid ratio (1:128). The lysine residues have favorable interactions with specific oxygen atoms of the phospholipid headgroups, indicating the preferred localization of these residues at the lipid/water interface.
Insights
Hydrophobic mismatch in proteins is alleviated by peptide tilting and lipid ordering under positive mismatch conditions. Negative mismatch is resolved through bilayer bending and lysine residue snorkeling, impacting membrane protein function.
Area of Science:
- Biophysics
- Computational Biology
- Membrane Protein Dynamics
Background:
- Hydrophobic mismatch, the difference between protein trans-membrane segment length and lipid bilayer width, influences membrane protein function.
- Understanding mismatch alleviation is crucial for predicting protein behavior in cellular membranes.
Purpose of the Study:
- To investigate hydrophobic mismatch alleviation mechanisms in trans-membrane KALP peptides within phospholipid bilayers.
- To systematically study the effects of varying peptide length and lipid hydrophobic length on mismatch resolution.
Main Methods:
- Molecular dynamics simulations of KALP peptides (KALP15-31) in DLPC, DMPC, and DPPC lipid bilayers.
- Systematic variation of peptide length and lipid hydrophobic length to create diverse mismatch conditions.
- Simulations conducted at different peptide/lipid molar ratios (1:25 and 1:128) with durations of 50-200 ns.
Main Results:
- Positive mismatch is alleviated primarily by peptide tilting and secondarily by increased lipid ordering.
- Negative mismatch is resolved through local bilayer bending and lysine residue "snorkeling."
- Higher peptide/lipid ratios result in slower peptide and lipid dynamics; lysine residues prefer the lipid/water interface.
Conclusions:
- Peptide tilting and lipid ordering are key mechanisms for resolving positive hydrophobic mismatch.
- Bilayer bending and residue "snorkeling" are important for negative mismatch resolution.
- Peptide and lipid dynamics are influenced by concentration, and lysine residues show specific interfacial preferences.
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