Department of Biochemistry, University of Nevada, Reno, Nevada 89557-0014.
Plant Physiol. 1992 Aug;99(4):1551-5. doi: 10.1104/pp.99.4.1551.
Results presented here indicate that 2'-carboxyarabinitol (CA) is the in vivo precursor and product of 2'-carboxyarabinitol 1-phosphate (CA1P) metabolism in leaves. When [2-(14)C]CA was fed in the light to leaves of five species known to be highly active in CA1P metabolism (Phaseolus vulgaris, Lycopersicon esculentum, Helianthus annuus, Petunia hybrida, and Beta vulgaris), [(14)C]CA1P was formed in the dark. Reillumination of a Phaseolus leaf caused this [(14)C]CA1P to be rapidly metabolized to [(14)C]CA (t((1/2)) = 1 min). The epimer 2'-carboxyribitol could not substitute for CA in the dark synthesis of CA1P, and CA in the anionic form was a better substrate than CA in the lactone form. In leaves of Phaseolus vulgaris, the active CA pool size used in the dark synthesis of CA1P is between about 70 and 110 nanomoles per milligram of chlorophyll. The photosynthetic electron transport inhibitor diuron did not affect the dark synthesis of [(14)C]CA1P, but did greatly reduce the rate of its subsequent light degradation (t((1/2)) = approximately 10 min). Dark synthesis of [(14)C]CA1P was inhibited by dithiothreitol and NaF. From the present data, we suggest that CA1P and CA participate in a metabolic substrate cycle in vivo.
这里呈现的结果表明，2'-羧基阿拉伯糖醇（CA）是 2'-羧基阿拉伯糖醇 1-磷酸（CA1P）代谢在叶片中的体内前体和产物。当[2-(14)C]CA 在光下被喂食到五种已知在 CA1P 代谢中非常活跃的物种（菜豆、番茄、向日葵、矮牵牛和甜菜）的叶片中时，[(14)C]CA1P 在黑暗中形成。对菜豆叶片的再光照导致[(14)C]CA1P 迅速代谢为[(14)C]CA（t((1/2)) = 1 分钟）。差向异构体 2'-羧基核糖醇不能替代 CA 来暗合成 CA1P，并且阴离子形式的 CA 比内酯形式的 CA 是更好的底物。在菜豆叶片中，用于暗合成 CA1P 的活性 CA 池大小约为每毫克叶绿素 70 至 110 纳摩尔。光合电子传递抑制剂敌草隆不影响[(14)C]CA1P 的暗合成，但大大降低了其后光降解的速率（t((1/2)) = 约 10 分钟）。二硫苏糖醇和 NaF 抑制[(14)C]CA1P 的暗合成。根据目前的数据，我们认为 CA1P 和 CA 参与体内代谢底物循环。
