Influence of the ionic environment on the conformation of aspartic acid and possible relevance to its neurotransmitter action.
The conformational changes of aspartic acid, a possible neurotransmitter, induced by increasing ionic strength were investigated by means of NMR spectroscopy. The effects of Li, Na, K, and Cs chlorides in basic and neutral conditions were characterized. The effects of the presence of both Ca2+ and Na+ or K+ were also examined. The results always showed a relative stabilization of the two conformers with gauche carboxylates at the expense of the anticonformer. The significant quantitative difference found between Na+ and K+ in basic solutions, as well as between calcium-free and calcium-containing solutions, may bear some relevance for the role of aspartate as a CNS neurotransmitter.
D001224:Aspartic Acid / Q000502:physiology; D002412:Cations; D008958:Models, Molecular; D008968:Molecular Conformation; D018377:Neurotransmitter Agents; D009994:Osmolar Concentration
D002412:Cations; D018377:Neurotransmitter Agents; D001224:Aspartic Acid