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United States Department of Agriculture

Agricultural Research Service

Title: Quantum Mechanical Conformation Analyses of Cellobiose

Authors
item French, Alfred
item Johnson, Glenn

Submitted to: European Carbohydrate Symposium
Publication Type: Abstract Only
Publication Acceptance Date: March 15, 2006
Publication Date: April 1, 2006
Citation: French, A.D., Johnson, G.P. 2006. Quantum mechanical conformation analyses of cellobiose. European Carbohydrate Symposium. 84(4). p. 603-612.

Technical Abstract: Rotations about the bonds to the glycosidic oxygen atom are the primary determinants of the shape properties of cellobiose and cellulose. Their preferred values can be predicted by consulting the classical Ramachandran map, or f, y energy surface. Earlywork was followed by Simon, Scheraga and Manley, still based on rigid glucose rings and empirical energy functions. Subsequently we used flexibile relaxed models based on the MM2 and MM3 empirical methods and hybrids of quantum mechanics and MM3. Those maps show much lower energy for chain-folding conformations than the rigid-residue work. Our most recent cellobiose surfaces are based on MM4 and AMBER* empirical methods and on HF/6-31G* quantum mechanics. All of these methods vary in their predictions of likely shapes for cellobiose. A major problem is finding the best combinations of the orientations of the exo-cyclic groups. Also, we have studied some analogs of cellobiose to better understand the underlying reasons for the calculated energy surfaces.

Last Modified: 12/17/2014
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