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Relaxed energetic maps of kappa-carrabiose: a DFT study
N Yousfi1, M Sekkal-Rahal, A Sayede
1Faculté des Sciences, Laboratoire L2MSM, Université Djillali Liabes de Sidi Bel Abbes, B.P. 89, Sidi Bel Abbes 22000, Algeria.
Journal of Computational Chemistry
|February 4, 2010
Summary
Computational chemistry explored kappa-carrabiose conformations. Full optimization of low-energy conformers is crucial for accurate energetic analysis of disaccharides.
Area of Science:
- Computational Chemistry
- Carbohydrate Chemistry
- Molecular Modeling
Background:
- Kappa-carrabiose is a disaccharide with potential biological relevance.
- Understanding its conformational landscape is key to elucidating its properties.
Purpose of the Study:
- To investigate the conformational space of kappa-carrabiose in gas and solution phases.
- To evaluate the impact of basis sets and computational methods on conformational energies.
Main Methods:
- Density Functional Theory (DFT) using B3LYP functional with 6-31G(d) basis set.
- Relaxed and rigid energetic contour maps were generated.
- Solvation effects were simulated using the Onsager model.
- Full optimizations of low-energy conformers were performed.
- MP2 calculations were conducted for comparison.
Main Results:
- Energetic maps revealed multiple low-energy conformers for both charged and neutral kappa-carrabiose.
- Basis set augmentation (e.g., adding diffuse/polarization functions) refined energy landscapes.
- A significant energy reversion between the two lowest minima was observed for charged kappa-carrabiose in the gas phase, attributed to grid limitations.
- Full optimization resolved discrepancies and identified true energy minima.
Conclusions:
- Potential energy maps are valuable but require subsequent full optimization for accurate conformational energy determination.
- The choice of computational method and basis set significantly influences the predicted conformational preferences of kappa-carrabiose.
- Accurate conformational analysis is essential for understanding the behavior of disaccharides.
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