A QM/MM analysis of the conformations of crystalline sucrose moieties

Alfred D. French, Anne Marie Kelterer, Christopher J. Cramer, Glenn P. Johnson, Michael K. Dowd

Research output: Contribution to journalArticleResearchpeer-review

Abstract

Both ab initio quantum mechanics (QM) and molecular mechanics (MM) were used to produce a hybrid energy surface for sucrose that simultaneously provides low energies for conformations that are observed in crystal structures and high energies for most unobserved structures. HF/6-31G* QM energies were calculated for an analogue based on tetrahydropyran (THP) and tetrahydrofuran (THF). Remaining contributions to the potential energy of sucrose were calculated with MM. To do this, the MM surface for the analogue was subtracted from the MM surface for the disaccharide, and the QM surface for the analogue was added. Prediction of the distribution of observable geometries was enhanced by reducing the strength of the hydrogen bonding. Reduced hydrogen-bonding strength is probably useful because many crystalline sucrose moieties do not have intramolecular hydrogen bonds between the fructose and glucose residues. Therefore, hydrogen bonding does not play a large role in determining the molecular conformation. On the hybrid energy surface that was constructed with a dielectric constant of 3.5, the average potential energy of 23 sucrose moieties from crystal structures is 1.16 kcal/mol, and the population of observed structures drops off exponentially as the energy increases. Copyright (C) 2000 Elsevier Science Ltd.

Original languageEnglish
Pages (from-to)305-322
Number of pages18
JournalCarbohydrate Research
Volume326
Issue number4
DOIs
Publication statusPublished - 30 Jun 2000

Fingerprint

Molecular mechanics
Quantum theory
Mechanics
Sucrose
Conformations
Hydrogen bonds
Crystalline materials
Potential energy
Interfacial energy
Hydrogen Bonding
Crystal structure
Disaccharides
Fructose
Permittivity
Molecular Conformation
Glucose
Geometry
Hydrogen
Population

Keywords

  • 2-Methoxytetrahydrofuran
  • 2-Methoxytetrahydropyran
  • Carbohydrates
  • exo-Anomeric effect
  • Force field
  • HF/6-31G*
  • MM3
  • Modeling
  • Non-additivity
  • Sugar

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Organic Chemistry

Cite this

A QM/MM analysis of the conformations of crystalline sucrose moieties. / French, Alfred D.; Kelterer, Anne Marie; Cramer, Christopher J.; Johnson, Glenn P.; Dowd, Michael K.

In: Carbohydrate Research, Vol. 326, No. 4, 30.06.2000, p. 305-322.

Research output: Contribution to journalArticleResearchpeer-review

French, Alfred D. ; Kelterer, Anne Marie ; Cramer, Christopher J. ; Johnson, Glenn P. ; Dowd, Michael K. / A QM/MM analysis of the conformations of crystalline sucrose moieties. In: Carbohydrate Research. 2000 ; Vol. 326, No. 4. pp. 305-322.
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