Incorporation of 18(O) into oxalic, L-threonic and L-tartaric acids during cleavage of L-ascorbic and 5-keto-D-gluconic acids in plants
1997
Saito, K. | Ohmoto, J. | Kuriha, N.
L-[1,6-14C]Ascorbic acid was administered to young leaves of Pelargonium. 5-Keto-D-[1-14C]gluconic acid, a metabolic product of L-[1-14C]ascorbic acid in grape, was supplied to young leaves of Pelargonium, parsley, bean and grape in the presence of 18O2 or H218O. From the 18O incorporated into oxalic and L-threonic acids, which were C2/C3 cleavage products of L-ascorbic acid, and into L-tartaric acid, which was a C4/C5 cleavage product of 5-keto-D-gluconic acid, the number of oxygen atoms incorporated into the respective organic acids was calculated. The data strongly suggest that a cleavage mechanism of C2/C3 of L-ascorbic acid involves both oxygenase and hydrolase reactions but that cleavage of C4/C5 of 5-keto-D-gluconic acid is due only to hydrolase.
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