Formation of L-(+)-Tartaric Acid in Leaves of the Bean, Phaseolus vulgaris L.: Radioisotopic Studies with Putative Precursors

概要

論文の詳細を見る
The biosynthetic pathway from D-glucose to L-(+)-tartaric acid (TA) in detached leaves of the bean, Phaseolus vulgaris L., was studied in three cultivars, two of which were known to contain TA and one of which lacked TA, with the aid of several putative radiolabeled intermediates, namely D-[1-^<14>C]glucose, D-[6-^<14>C]glucose, D-[U-^<14>C]glucose, D-[U-^<14>C]gluconate, L-[U-^<14>C]-ascorbic acid, L-[1-^<14>C]idonate, D-xylo-5-[U-^<14>C]hexulosonate, D-xylo-5-[1-^<14>C]hexulosonate, D-xylo-5-[6-^<14>C]hexulosonate and L-[U-^<14>C]threonate. D-[U-^<14>C]Glucose and D-[U-^<14>C]gluconate were converted to TA with low isotopic yield but this yield was further reduced when leaf tissues were supplied with unlabeled D-gluconate or D-xylo-5-hexulosonate. D-xylo-5-[U-^<14>C]Hexulosonate and D-xylo-5-[1-^<14>C]hexulosonate were good precursors of TA. D-xylo-5-[6-^<14>C]Hexulosonate did not furnish ^<14>C to TA. Addition of a metabolic product of D-xylo-5-hexulosonate (which was labeled by D-xylo-5-[1-^<14>C]hexulosonate but not by D-xylo-5-[6-^<14>C]hexulosonate) to leaves labeled with D-xylo-5-[1-^<14>C]hexulosonate doubled the incorporation of ^<14>C into TA. L-[U-^<14>C]Ascorbic acid, L-[1-^<14>C]idonate and L-[U-^<14>C]threonate failed to produce labeled TA. A metabolic scheme to accommodate these observations is presented.
日本植物生理学会の論文