Abstract
As a type of interaction of neurotransmitters with a charged surface, adsorption of nine neurotransmitters. onto a gold electrode has been studied by measuring specular reflecti vity in phosphate buffer (pH 6.9). The neurotransmitters examined are: (a), γ-aminobutyric acid, glycine, β-alanine, dopamine, norepinephrine, epinephrine and (b), acetylcholine, glutamic acid, aspartic acid. All of these neurotrans mitters are adsorbed in the potential range around the point of zero charge. However, the difference in the potential dependence of adsorption is clearly observed'between groups (a) and (b). The adsorption potential profiles obtained for group (a)are of a quasi-bell-type, indicating no orientational change takes place in their adsorptiondesorption processes. On the other, hand, group (b) exhibits rather complicated profiles, implying conformational changes in the adsorbed molecules may occur depending on the surface charge. Groups (a) and (b) are known to function as inhibitory and excitatory neurotransmitters, respectively, in central nervous system. Then the results suggest that electrosorption of neurotransmitters may provide a very simple model of their combinations at the receptor sites on synaptic membranes. In this paper, optical reflection method is reconfirmed to be useful to recognize the adsorbed molecules on the electrode surface, in situ, and to be promissing to develop the bioelectr ochemical applications.
