Search

application/pdf, 論文(Article)

東京家政大学生活科学研究所研究報告は、本研究所の本年度の活動成果を取りまとめたものです。本研究報告の内容の一部は、別途学会誌等に発表されることがありますのでご了承ください。

本論文の要旨は,第33回広島大学歯学会総会(平成12年6月24日)において発表した。

本論文の要旨は,平成9年7月の第12回中国・四国歯科麻酔研究会において発表した。

Decarboxylation of L -threo-3,4-dihydroxyphenylserine ( L -threo-DOPS) was examined in vitro using hog renal L -aromatic amino acid decarboxylase. Decarboxylation was measured by chemical assay of the reaction product, noradrenaline (NA), and was found to occur specifically with the L -isomer and not with the D -isomer. The maximum rate of decarboxylation of L -threo-DOPS was obtained in the presence of 10 μM pyridoxal phosphate (PALP) at 37° and pH 8.6. Under the optimal conditions, Km and Vmax for L -threo-DOPS were 4 × 10−4 M and 2.80 nmoles NA/mg of protein/min respectively. Decarboxylation of L -threo-DOPS was competitively inhibited by L -3,4-dihydroxyphenylalanine ( L -DOPA) and L -5-hydroxytryptophan ( L -5-HTP). D -Threo-DOPS and D -DOPA at 0.125 mM inhibited the decarboxylation of L -threo-DOPS to about half that of the control. D -Erythro-DOPS at higher concentrations had a slight inhibitory effect on the decarboxylation of L -threo-DOPS, while D -5-HTP and D -tryptophan up to 1 mM had no effect whatever. The inhibition induced by D -threo-DOPS was competitive when the concentration of D -threo-DOPS was below that of L -threo-DOPS. When the concentration of the D -isomer was higher than that of the L -isomer, a noncompetitive inhibition was observed. Inhibition due to inactivation of PALP by interaction of PALP and D -isomer was ruled out. These results suggest that inhibition of decarboxylation of L -threo-DOPS by D -threo-DOPS is the result of the interaction of the D -isomer with the enzyme.

この論文は国立情報学研究所の電子図書館事業により電子化されました。