氧-17只出现在水应激大豆叶中的蛋白质中,标有 (17) O2 2 的标签
Terry Gullion1, Tsyr-Yan Yu, Manmilan Singh
1Department of Chemistry, West Virginia University, Morgantown, West Virginia 26506, USA.
Journal of the American Chemical Society
|August 5, 2010
概括
大豆叶中的水应激会将氧化酶反应中产生的甘氨酸直接转向蛋白质合成. 这一发现表明,水应力有效地抑制了这些植物的光呼吸.
科学领域:
- 植物生理学 植物生理学
- 生物化学 生物化学
- 分子生物学分子生物学
背景情况:
- 里布洛二酸碳氧酶-氧化酶 (Rubisco) 是光合作用中的关键酶,但其氧化酶活性导致光呼吸,这是一个浪费过程.
- 甘氨酸是光吸的产物,其代谢命运对于理解植物中的碳流量至关重要.
- 已知水应激会影响植物生理过程,包括气体交换和光合作用.
研究的目的:
- 为了研究水应激下在大豆叶中Rubisco的氧化酶活性产生的甘氨酸的代谢命运.
- 为了确定水应激是否影响糖氨酸融入蛋白质或其他细胞组件.
- 为了阐明水应激对大豆植物光呼吸的影响.
主要方法:
- 使用了一种旋转回声-亚亚巴特通道双共振 (13) C {(17) O} 固态核磁共振 (NMR) 实验.
- 暴露于完整的,水应力大豆叶子,以同位素标记的二氧化碳 ((13) CO(2)) 和氧气 ((17) O(2)).
- 在糖氨酸中对 (13) C 和 (17) O 的同位素丰富和其纳入蛋白质的监控.
主要成果:
- 从氧化酶反应中产生的甘氨酸完全被纳入水应力大豆叶中的蛋白质或蛋白质前体.
- 由于气体交换减少和口腔阻力增加,水应力将卡尔文循环 (13) C 丰富度降低到 35%.
- 足够的 (17) O(2) 标签证实了氧化酶产物形成的增加, (17) O同位素度增加了20倍.
结论:
- 在水应激下直接将甘氨酸纳入蛋白质表明显著抑制光呼吸.
- 水应激改变了大豆叶中的碳分区,有利于蛋白质合成而不是光呼吸道.
- 固态NMR是一种强大的工具,可以在压力条件下追踪完整的植物组织中的代谢途径.
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