Structural And Interaction Analysis Of Helical Heparin Oligosaccharides With The Fragment Molecular Orbital Method

The fragment molecular orbital method (FMO) was applied to the geometry optimization of several heparin oligosaccharides at the RHF/6-31(+)G(d) level combined with the polarizable continuum model (PCM). For comparison, GLYCAM force field optimization in explicit solvent was also conducted. Good accuracy of FMO was demonstrated in comparison to ab initio at the MP2/PCM level. The interaction analysis was conducted using the pair interaction energy decomposition analysis (PIEDA), and the role of hydrogen bonding and solvent was elucidated in the helix formation of heparin in solution. (C) 2009 Wiley Periodicals, Inc. Int J Quantum Chem 109: 2033-2045, 2009