title: Ab initio conformational maps for disaccharides in gas phase and aqueous solution.
abstract: Ab initio conformational maps for beta-lactose in both the gas phase and in aqueous solution have been constructed at the HF/6-31G(d,p) level of calculation. The results of the gas-phase ab initio calculations allow us to conclude that a rigid conformational map is able to predict the regions of the minima in the potential energy surface of beta-lactose, in full agreement with those found in the relaxed conformational map. The solvation effects do not give rise to any new local minimum in the potential energy surface of beta-lactose, but just change the relative Boltzmann populations of the conformers found in the gas-phase calculations. The values obtained for heteronuclear spin coupling constant (3J(H,C)), using the seven most stable conformers in solution are in good agreement with the available experimental values. This is a good indication that ab initio rigid conformational maps can be reliably used to sort the most stable conformers of beta-lactose.
authors.affiliation: Departamento de Química da Universidade, Federal Rural do Rio de Janeiro, BR-465, Km 47, Seropédica, Rio de Janeiro CEP 23.890-000, Brazil. clarissa-dq@ufrrj.br
authors.forename: Clarissa O
authors.initials: CO
authors.lastname: da Silva
authors.forename: Marco A C
authors.initials: MA
authors.lastname: Nascimento
mesh_terms: D005740:Gases; D007785:Lactose / Q000737:chemistry*; D008432:Mathematical Computing; D008956:Models, Chemical; D008968:Molecular Conformation; D012996:Solutions; D013499:Surface Properties; D013816:Thermodynamics
chemical_list: D005740:Gases; D012996:Solutions; D007785:Lactose