Strong preferences of dopamine and l-dopa towards lipid head group: importance of lipid composition and implication for neurotransmitter metabolism

J. Neurochem. (2012) 122, 681690. Abstract The interactions of the neurotransmitter dopamine, and its precursor l-dopa, with membrane lipids were investigated through a set of molecular dynamic simulations with all atom resolution. The results obtained indicate that both dopamine and l-dopa have a pronounced association with the lipid head groups, predominantly mediated through H-bonds. As a result the molecules are anchored to the interfacial region of the membrane. The strength of this interaction is dependent on lipid composition the presence of phosphatidylserine leads to an increase in the strength of this interaction, resulting in an H-bond network with a lifetime much longer than the timescale of our simulations. Also, bilayers that include sphingomieline and cholesterol interact strongly with dopamine and l-dopa. We postulate that the high membrane association that we have observed for both dopamine and l-dopa could have the following effects: 1) when on the plasma membrane exterior, favour the availability of these compounds for cell membrane uptake processes and, 2) when on an internal membrane surface, accentuate the importance of membrane-bound metabolizing enzymes over their soluble counterparts.