Retrobiosynthetic nuclear magnetic resonance analysis of amino acid biosynthesis and intermediary metabolism. Metabolic flux in developing maize kernels
Retrobiosynthetic nuclear magnetic resonance analysis of amino acid biosynthesis and intermediary metabolism. Metabolic flux in developing maize kernels
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DOI：
10.1104/pp.125.3.1178
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发表时间：
2001-03-01
期刊：
影响因子：
7.4
通讯作者：
Eisenreich, W
中科院分区：
文献类型：
--
作者：
Glawischnig, E;Gierl, A;Eisenreich, W
代谢网络的信息可以为代谢工程靶标的设计提供基础。为了研究谷物中的代谢通量，将发育中的玉米（Zea mays）籽粒在含有[U-C-13（6）]葡萄糖或[1，2-C-13（2）]乙酸盐的培养基上无菌培养。生长后，氨基酸，脂质和谷甾醇被分离的内核以及从驾驶室，和他们的C-13同位素组成进行了测定，通过定量核磁共振光谱。高度特异性的标记模式被用来分析代谢途径，导致氨基酸和三萜的定量基础上。数据显示，丝氨酸是由磷酸甘油酸和甘氨酸产生的。赖氨酸完全通过二氨基庚二酸途径形成，谷甾醇完全通过甲羟戊酸途径合成。氨基酸和谷甾醇的标记数据用于重建关键代谢中间体（例如乙酰辅酶A、丙酮酸、磷酸烯醇丙酮酸、赤藓糖4-磷酸和Rib 5-磷酸）的标记模式，其揭示关于中间代谢或发育中的玉米籽粒中的碳核的定量信息。外源性乙酸充当谷甾醇的有效前体，以及天冬氨酸和谷氨酸家族的氨基酸;相比之下，在质体隔室中形成的代谢物显示出低乙酸掺入。
Information on metabolic networks could provide the basis for the design of targets for metabolic engineering. To study metabolic flux in cereals, developing maize (Zea mays) kernels were grown in sterile culture on medium containing [U-C-13(6)]glucose or [1,2-C-13(2)]acetate. After growth, amino acids, lipids, and sitosterol were isolated from kernels as well as from the cabs, and their C-13 isotopomer compositions were determined by quantitative nuclear magnetic resonance spectroscopy. The highly specific labeling patterns were used to analyze the metabolic pathways leading to amino acids and the triterpene on a quantitative basis. The data show that serine is generated from phosphoglycerate as well as from glycine. Lysine is formed entirely via the diaminopimelate pathway and sitosterol is synthesized entirely via the mevalonate route. The labeling data of amino acids and sitosterol were used to reconstruct the labeling patterns of key metabolic intermediates (e.g. acetyl-coenzyme A, pyruvate, phosphoenolpyruvate, erythrose 4-phosphate, and Rib 5-phosphate) that revealed quantitative information about carbon nux m the intermediary metabolism or developing maize Kernels. Exogenous acetate served as an efficient precursor of sitosterol, as well as of amino acids of the aspartate and glutamate family; in comparison, metabolites formed in the plastidic compartments showed low acetate incorporation.