Treatment of ionic species in force-field calculations: sulfate and carboxylate groups in carbohydrates.
Ab initio computations with different basis sets (up to 6-31 + G* *) on methylsulfate and N-methylsulfate anions and on the ionic and neutral forms of acetic acid are presented. The atomic charges for the O-sulfo group, computed using the Merz-Kollman method at the highest level of theory, were inserted in a MM2-derived force-field; its current parametrization affords a 0.22 A root-mean-square deviation with respect to five crystal structures of sulfated monosaccharides.
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1st Chimica Macromolecole del CNR, Milano, Italy.
Pumilia
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Cassinari
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Ragazzi
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D000085:Acetates; D019342:Acetic Acid; D000838:Anions; D002236:Carbohydrate Conformation; D008958:Models, Molecular; D008962:Models, Theoretical; D008968:Molecular Conformation; D013431:Sulfates; D013463:Sulfuric Acid Esters
D000085:Acetates; D000838:Anions; D013431:Sulfates; D013463:Sulfuric Acid Esters; D019342:Acetic Acid; C033522:methyl sulfate