A COMPUTATIONAL STUDY OF SOLVENT EFFECTS ON THE CONFORMATION OF DOPAMINE

The solution conformation of the neurotransmitter dopamine is investigated with the AM1-SM1 solvation model as implemented in the program AMSOL. AMSOL invokes the AM1 Hamiltonian and evaluates solvent effects based on a continuum model of solvation free energy. In the current work, calculations are performed on the neutral, N-protonated, and OH-deprotonated forms of dopamine with both AM1 (gas phase) and AM1-SM1 (aqueous solution). For both N-protonated and OH-deprotonated dopamine, the gas-phase AM1 calculations predict the anti conformation to be much higher in energy than gauche conformations. AMSOL, however, predicts the anti conformation to be an important contributor to the solution conformer population at neutral pH, in agreement with experimental observations.