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Brownian dynamics simulation of helix-capping motifs
Tongye Shen1, Chung F Wong, J Andrew McCammon
1Department of Chemistry & Biochemistry, University of California, San Diego, La Jolla, CA 92093-0365, USA. tshen@ucsd.edu
Biopolymers
|October 1, 2003
Summary
Helix-capping motifs stabilize alpha-helices. Simulations suggest side-chain interactions, not just hydrogen bonds, stabilize the S**D capping box motif, influencing helix conformation.
Area of Science:
- Biophysics
- Computational Biology
- Structural Biology
Background:
- Helix-capping motifs are crucial for alpha-helix stability and defining helix boundaries.
- The S**D capping box motif is widely studied for its role in helix stabilization.
Purpose of the Study:
- To investigate the propensity of XAAD sequences to form helix capping motifs using Brownian dynamics simulations.
- To correlate simulation findings with protein structural database analyses.
- To elucidate the stabilizing factors of the S**D capping box motif.
Main Methods:
- Microsecond scale Brownian dynamics simulations of ten XAAD sequences.
- Analysis of a structural database of proteins.
- Principal component analysis (PCA) of simulation trajectories.
- Comparison with explicit-solvent molecular dynamics simulations.
Main Results:
- Simulations indicate that one proposed hydrogen bond in the S**D motif may be less critical for stabilization.
- Side-chain interactions between the capping residue and the third downstream residue appear to contribute to motif stability.
- PCA revealed that the first two principal components capture significant conformational fluctuations, differentiating between all-helical and capped states.
Conclusions:
- The study refines the understanding of stabilizing forces within helix-capping motifs.
- Side-chain interactions play a significant role in S**D capping box stability.
- Conformational dynamics simulations provide insights into helix-capping motif formation and transitions.