53.ABA代謝物質ファゼイン酸の還元酵素の性質(口頭発表)

概要

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Abscisic acid (ABA) is inactivated through metabolism. First, ABA is hydroxylated by 8'-hydroxylase to give 8'-hydroxy-ABA. 8'-Hydroxy-ABA is spontaneously isomerized to phaseic acid (PA). PA is converted to dihydrophaseic acid (DPA) and epi-DPA by PA 4'-reductase. 8'-Hydroxy-ABA and PA still have biological activity although the activity is low, but DPAs are almost inactive. The gene of ABA 8'-hydroxylase was identified in Arabidopsis and other plants, and its inhibitors were developed to protect plants from water stress. However, the research on PA 4'-reductase has not progressed. We have started the research on the enzyme for regulating inactivation of ABA. Several plants were screened for detection of the PA 4'-reductase activity. The supernatants of the extracts after centrifugation were used to detect the PA 4'-reductase activity. The enzyme activity was found in the extract of immature garden pea (Pisum sativum). The reaction product was DPA, and epi-DPA was not detected. The optimum pH is 8.0, and NADPH is a better coenzyme than NADH. The extract kept 80% of activity after stored 9 days at -80℃. Purification of the enzyme is under progress.
植物化学調節学会の論文
2008-10-06