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Predicting the conformational states of cyclic tetrapeptides
Nicolas Loiseau1, Jean-Marie Gomis, Jérôme Santolini
1CNRS-URA 2096, Protéines Membranaires Transductrices d'Energie, DBJC, et Département de Biologie, Joliet-Curie, CEA-Saclay, 91191 Gif-sur-Yvette cedex, France.
Biopolymers
|July 2, 2003
Summary
Standard molecular mechanics accurately predicts cyclic tetrapeptide conformations in solution. This computational method, validated by experimental data, aids drug design by determining conformer populations and orientations for biologically active molecules like tentoxin.
Area of Science:
- Biochemistry
- Computational Chemistry
- Structural Biology
Background:
- Cyclic tetrapeptides, often fungal metabolites, possess biological activity (phytotoxic, cytostatic) influenced by their solution conformations.
- Accurate prediction of cyclotetrapeptide conformational populations is crucial for drug design and understanding biological activity.
Purpose of the Study:
- To validate a standard molecular mechanics approach for predicting cyclotetrapeptide conformations and conformer proportions.
- To assess the method's reliability using experimental data from synthesized peptides and literature.
Main Methods:
- Utilized standard molecular mechanics with the TRIPOS force field to compute potential energies of conformers.
- Incorporated solvent effects using dielectric constants or free energy of solvation calculations (SILVERWARE algorithm).
- Validated predictions against experimental synthesis, NMR analysis, and literature data for cyclo(Gly)(4), cyclo(Ala)(4), cyclo(Sar)(4), cyclo(SarGly)(2), and tentoxin.
Main Results:
- The molecular mechanics approach provided satisfactory predictions of peptide backbone conformation.
- Accurate determination of carbonyl group orientation and conformer nature was achieved.
- Calculated conformer proportions for tentoxin closely matched experimental findings across different solvents.
Conclusions:
- Standard molecular mechanics is a reliable and efficient method for predicting cyclotetrapeptide conformations and their solution populations.
- This computational strategy facilitates drug design and the study of biologically active cyclic peptides.
- The method accurately accounts for solvent effects, enhancing predictive power for molecules like tentoxin.