Williams M, Loewus F A
Department of Agricultural Chemistry, Washington State University, Pullman, Washington 99164.
Plant Physiol. 1978 Apr;61(4):672-4. doi: 10.1104/pp.61.4.672.
The metabolic fate of l-[4-(14)C]ascorbic acid has been examined in the grape (Vitis labrusca L.) and lemon geranium (Pelargonium crispum L. L'Hér. cv. Prince Rupert) under conditions comparable to data from l-[1-(14)C]ascorbic acid and l-[6-(14)C]ascorbic acid experiments. In detached grape leaves and immature berries, l-[4-(14)C]ascorbic acid and l-[1-(14)C]ascorbic acid were equivalent precursors to carboxyl labeled (+)-tartaric acid. In geranium apices, l-[4-(14)C]ascorbic acid yielded internal labeled (+)-tartaric acid while l-[6-(14)C]ascorbic acid gave an equivalent conversion to carboxyl labeled (+)-tartaric acid. These findings clearly show that two distinct processes for the synthesis of (+)-tartaric acid from l-ascorbic acid exist in plants identified as (+)-tartaric acid accumulators. In grape leaves and immature berries, (+)-tartaric acid synthesis proceeds via preservation of a four-carbon fragment derived from carbons 1 through 4 of l-ascorbic acid while carbons 3 through 6 yield (+)-tartaric acid in geranium apices.
在与L-[1-(14)C]抗坏血酸和L-[6-(14)C]抗坏血酸实验数据相当的条件下，对葡萄（美洲葡萄L.）和柠檬天竺葵（皱叶天竺葵L. L'Hér. cv. Rupert王子）中L-[4-(14)C]抗坏血酸的代谢命运进行了研究。在离体葡萄叶和未成熟浆果中，L-[4-(14)C]抗坏血酸和L-[1-(14)C]抗坏血酸是羧基标记的(+)-酒石酸的等效前体。在天竺葵顶端，L-[4-(14)C]抗坏血酸产生内部标记的(+)-酒石酸，而L-[6-(14)C]抗坏血酸向羧基标记的(+)-酒石酸的转化相当。这些发现清楚地表明，在被鉴定为(+)-酒石酸积累植物中，存在两种从L-抗坏血酸合成(+)-酒石酸的不同过程。在葡萄叶和未成熟浆果中，(+)-酒石酸的合成通过保留源自L-抗坏血酸碳1至4的四碳片段进行，而在天竺葵顶端，碳3至6产生(+)-酒石酸。
