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Does compactness induce secondary structure in proteins? A study of poly-alanine chains computed by distance geometry
1Department of Pharmaceutical Chemistry, University of California, San Francisco 94143-1204.
Journal of Molecular Biology
|August 26, 1994
Summary
Compactness can stabilize protein secondary structures like helices and sheets. However, the specific amount of structure depends on how it
Area of Science:
- Computational chemistry
- Biophysics
- Polymer physics
Background:
- Lattice and off-lattice studies suggest compactness influences polymer chain structure.
- Previous research indicates varying amounts of induced secondary structure.
Purpose of the Study:
- To investigate the role of compactness in inducing secondary structure in poly-alanine chains.
- To determine how compactness affects the stability and specificity of protein secondary structures.
Main Methods:
- Utilized distance geometry to generate random conformations of compact poly-alanine chains.
- Applied compactness and excluded volume constraints without other energy terms.
- Introduced small energy perturbations using the AMBER force field for refinement.
Main Results:
- Compactness significantly stabilizes secondary structure, but the quantity depends on definition criteria.
- Stabilization free energy is criterion-independent.
- Alpha-helices formed readily with minor energy refinements, while beta-sheets required larger ones.
Conclusions:
- Compactness provides stability to protein secondary structures but lacks specificity.
- Compactness acts as a statistical force (ensemble effect) rather than a specific interaction like hydrogen bonding.