Malate Metabolism in the Dark After CO(2) Fixation in the Crassulacean Plant Kalanchoë tubiflora.
Malate Metabolism in the Dark After CO(2) Fixation in the Crassulacean Plant Kalanchoë tubiflora.
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景天科植物长寿花 CO(2) 固定后黑暗中的苹果酸代谢。
DOI：
10.1104/pp.94.2.826
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发表时间：
1990
期刊：
影响因子：
7.4
通讯作者：
J. Siedow
中科院分区：
文献类型：
--
作者：
W. Kalt;C. Osmond;J. Siedow
在16小时的黑暗循环中，研究了景天科植物筒花吊兰在暴露于（13）CO（2）中2小时后的[（13）C]苹果酸代谢。从标记的组织中提取的[（13）C]苹果酸的核磁共振光谱显示，苹果酸到线粒体的瞬时通量，通过[4-（13）C]苹果酸到[1-（13）C]苹果酸的随机化由酶估计，在黑暗期间变化很大。在15和25摄氏度下，线粒体中苹果酸标记的随机化程度在黑暗期的早期和晚期最大，在午夜最小，此时（13）CO（2）吸收率最高。标记的苹果酸盐的随机化在苹果酸盐合成最初发生后持续许多小时。内部呼吸的（12）CO（2）也是苹果酸形成的碳源。在15摄氏度，15%的总苹果酸是由呼吸的（12）CO（2）形成的，而在25摄氏度，49%的积累的苹果酸来自呼吸的（12）CO（2）。一些由外部（13）CO（2）合成的苹果酸也在夜间呼吸。在15和25摄氏度下，黑暗期间呼吸的总[（13）C]苹果酸的比例相似，随着夜间的进展，新形成的[（13）C]苹果酸的呼吸增加。这些数据进行了讨论，苹果酸的相对流量的线粒体和液泡在黑暗中CO（2）固定。
The metabolism of [(13)C]malate was studied in the Crassulacean plant Kalanchoë tubiflora following exposure to (13)CO(2) for 2 hour intervals during a 16 hour dark cycle. Nuclear magnetic resonance spectroscopy of [(13)C]malate extracted from labeled tissue revealed that the transient flux of malate to the mitochondria, estimated by the randomization of [4-(13)C]malate to [1- (13)C]malate by fumarase, varied substantially during the dark period. At both 15 and 25 degrees C, the extent of malate label randomization in the mitochondria was greatest during the early and late parts of the dark period and was least during the middle of the night, when the rate of (13)CO(2) uptake was highest. Randomization of labeled malate continued for many hours after malate synthesis had initially occurred. Internally respired (12)CO(2) also served as a source of carbon for malate formation. At 15 degrees C, 15% of the total malate was formed from respired (12)CO(2), while at 25 degrees C, 49% of the accumulated malate was derived from respired (12)CO(2). Some of the malate synthesized from external (13)CO(2) was also respired during the night. The proportion of the total [(13)C]malate respired during the dark period was similar at 15 and 25 degrees C, and respiration of newly formed [(13)C]malate increased as the night period progressed. These data are discussed with regard to the relative fluxes of malate to the mitochondria and the vacuole during dark CO(2) fixation.