The biochemistry of Rubisco in Flaveria
The biochemistry of Rubisco in Flaveria
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DOI：
10.1093/jxb/erm283
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发表时间：
2008-05-01
影响因子：
6.9
通讯作者：
Jesson, Linley K.
中科院分区：
文献类型：
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作者：
Kubien, David S.;Whitney, Spencer M.;Jesson, Linley K.
据报道，与 C-3 物种的酶相比，C-4 植物的 Rubiscos 具有更高的最大羧化率 (kcat(CO2)) 和 CO2 (K-c) 的米氏常数 (K-m)，但两种光合作用途径之间其他动力学参数的变化尚未得到广泛研究。 CO2/O-2 特异性 (S-C/O)、kcat(CO2)、K-c 以及 O-2 (K-o) 和 RuBP (Km-RuBP) 的 K-m 是在 25 摄氏度下，在从 16 种黄菊属（菊科）纯化的 Rubisco 中测量的。我们的分析包括黄菊属的两种 C-3 物种、四种 C-4 物种和十种 C-3-C-4 或 C-4 类物种，以及其他 C-4（玉米和苋菜）和 C-3（菠菜和藜）植物。 C-4 黄菊属物种的 S-C/O 约为 77 mol mol 21 ，比 C-3 物种的相应值低约 5%。对于来自 C-4 黄蜂的 Rubisco，kcat(CO2) 和 K-c 分别比来自 C-3 植物的 Rubisco 高 23% 和 45%。有趣的是，我们发现，C-4 物种 F. bidentis 和 F.trinervia 的 Rubisco K-o 与 C-3 Flaveria Rubiscos 相似（类似于 650 μM），而 C-4 物种 F. kochiana、F. australasica、Z. mays 和 A. edulis 的 Rubisco K-o 降低了 2 倍以上。 Km-RuBP 不存在与途径相关的差异。在 C-3-C-4 物种中，kcat(CO2) 和 Kc 通常与 C-3 Rubiscos 相似，但 K-o 值变化更大。 S-C/O与kcat(CO2)和K-c之间观察到典型的负相关关系，并且在kcat(CO2)和K-c之间观察到强正相关关系。然而，这些关系的统计显着性受到物种系统发育相关性的影响。
C-4 plants have been reported to have Rubiscos with higher maximum carboxylation rates (kcat(CO2)) and Michaelis-Menten constants (K-m) for CO2 (K-c) than the enzyme from C-3 species, but variation in other kinetic parameters between the two photosynthetic pathways has not been extensively examined. The CO2/O-2 specificity (S-C/O), kcat(CO2), K-c, and the K-m for O-2 (K-o) and RuBP (Km-RuBP), were measured at 25 degrees C, in Rubisco purified from 16 species of Flaveria (Asteraceae). Our analysis included two C-3 species of Flaveria, four C-4 species, and ten C-3-C-4 or C-4-like species, in addition to other C-4 (Zea mays and Amaranthus edulis) and C-3 (Spinacea oleracea and Chenopodium album) plants. The S-C/O of the C-4 Flaveria species was about 77 mol mol 21, which was approximately 5% lower than the corresponding value in the C-3 species. For Rubisco from the C-4 Flaverias kcat(CO2) and K-c were 23% and 45% higher, respectively, than for Rubisco from the C-3 plants. Interestingly, it was found that the K-o for Rubisco from the C-4 species F. bidentis and F. trinervia were similar to the C-3 Flaveria Rubiscos (similar to 650 mu M) while the K-o for Rubisco in the C-4 species F. kochiana, F. australasica, Z. mays, and A. edulis was reduced more than 2-fold. There were no pathway-related differences in Km-RuBP. In the C-3-C-4 species kcat(CO2) and Kc were generally similar to the C-3 Rubiscos, but the K-o values were more variable. The typical negative relationships were observed between S-C/O and both kcat(CO2) and K-c, and a strongly positive relationship was observed between kcat(CO2) and K-c. However, the statistical significance of these relationships was influenced by the phylogenetic relatedness of the species.