Fitness of amines for pseudocyclic conformation of lasalocid A.

Ionophore lasalocid A selectively transports amines across lipid membranes. The structures of amine-lasalocid complexes were calculated by a molecular mechanics technique. Four typical catecholamines were considered: serotonin, dopamine, noradrenaline and adrenaline. The fitness energy was introduced consisting of tension energies of amine and ionophore and the interaction energy between them. Four fitted complexes of the first three amines and two of the last one were found. They are characterized by interaction between lasalocid ligand oxygens and amine ammonium groups, and also between their aromatic rings. The fitness energy increase correlates well with the decrease of the transportation rate in the considered sequence of amines.