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Conformational studies of dextran [alpha-(1----6)-D-glucan]
B K Sathyanarayana1, E S Stevens
1Department of Chemistry State University of New York Binghamton 13901.
Journal of Biomolecular Structure & Dynamics
|October 1, 1984
Summary
Dextran and pustulan, both (1----6)-linked glucans, exhibit different conformational behaviors. This study reveals why dextran does not gel, unlike pustulan, due to favored conformations influencing structural regularity.
Area of Science:
- Carbohydrate Chemistry
- Computational Chemistry
- Polymer Science
Background:
- Dextran is a (1----6)-linked alpha-D-glucan polysaccharide.
- Pustulan is the corresponding (1----6)-linked beta-D-glucan.
- Understanding their conformational differences is key to explaining their distinct physical properties.
Purpose of the Study:
- To perform a theoretical conformational study of dextran.
- To compare dextran's conformation with pustulan.
- To elucidate the structural basis for dextran's inability to gel.
Main Methods:
- Calculated nonbonded, torsional, and hydrogen bond contributions to potential energy.
- Explored potential energy as a function of rotational angles (phi, psi, omega).
- Analyzed the conformational space of disaccharides and helices.
Main Results:
- Identified numerous local energy minima with minimal energy differences in the (phi, psi, omega)-space for both dextran and pustulan.
- Revealed significant differences in conformational behavior between (1----6)-alpha-D-glucans (dextran) and (1----6)-beta-D-glucans (pustulan).
- Dextran lacks favored conformations with high structural regularity, unlike pustulan.
Conclusions:
- The conformational differences between dextran and pustulan explain their distinct gelling properties.
- Dextran's lack of favored, regular conformations contributes to its inability to form gels.
- Pustulan's conformational preferences likely facilitate gel formation.