セロトニン(5-ハイドロオキシトリプタミン)および5-ハイドロオキシトリプトファンの酸解離

概要

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The acid dissociation equilibria in aqueous solutions of serotonin (5-HT) and 5-hydroxytryptophan (5-HTP) were studied by potentiometry at 25°and μ=0.1(NaClO_4). Microscopic equilibrium constants shown in chart 1 were calculated by three different methods. Methods A and B are based on the assumption that k_n is the same as the dissociation constants of tryptamine・HCl and 5-methoxytryptamine・HCl, respectively. In method C, the absorbance at 322 nm is taken as a measure of the concentration of the dissociated phenol. Results are listed in Tables I and II. 5-HT was found to be present completely in cationic form at the physiological pH of 7.4,and about 30% each as neutral and zwitterionic form at pH 10.5,whereas about 60% of 5-HTP was found to be present in the form corresponding to neutral form of 5-HT at pH 10.4.
社団法人日本薬学会の論文
1975-11-25