CONFORMATIONAL-ANALYSIS AND MOLECULAR-DYNAMICS SIMULATION OF LACTOSE

The conformational details of beta-lactose are investigated through mo lecular dynamics simulations in conjunction with the adiabatic potenti al energy map. The adiabatic energy map generated in vacuo contains fi ve local minima. The lowest energy structure on the map does not corre spond to the structure determined experimentally by NMR and the X-ray crystallography. When aqueous solvent effect is incorporated into the energy map calculation by increasing the dielectric constant, one of t he local minima in the vacuum energy map becomes the global minimum in the resultant energy map. The lowest energy structure of the energy m ap generated in aquo is consistent with the one experimentally determi ned. Molecular dynamics simulations starting from those five local min ima on the vacuum energy map reveal that conformational transitions ca n take place among various conformations. Molecular dynamics simulatio ns of the lactose and ricin B chain complex system in a stochastic bou ndary indicate that the most stable conformation in solution phase is bound to the binding site and that there are conformational changes in the exocyclic region of the lactose molecule upon binding.