Dijkhuizen L, Harder W
Antonie Van Leeuwenhoek. 1984;50(5-6):473-87. doi: 10.1007/BF02386221.
The Calvin cycle of carbon dioxide fixation constitutes a biosynthetic pathway for the generation of (multi-carbon) intermediates of central metabolism from the one-carbon compound carbon dioxide. The product of this cycle can be used as a precursor for the synthesis of all components of cell material. Autotrophic carbon dioxide fixation is energetically expensive and it is therefore not surprising that in the various groups of autotrophic bacteria the operation of the cycle is under strict metabolic control. Synthesis of phosphoribulokinase and ribulose-1,5-bisphosphate carboxylase, the two enzymes specifically involved in the Calvin cycle, is regulated via end-product repression. In this control phosphoenolpyruvate most likely has an alarmone function. Studies of the enzymes isolated from various sources have indicated that phosphoribulokinase is the target enzyme for the control of the rate of carbon dioxide fixation via the Calvin cycle through modulation of existing enzyme activity. In general, this enzyme is strongly activated by NADH, whereas AMP and phosphoenolpyruvate are effective inhibitors. Recent studies of phosphoribulokinase in Alcaligenes eutrophus suggest that this enzyme may also be regulated via covalent modification.
二氧化碳固定的卡尔文循环构成了一条生物合成途径，用于从一碳化合物二氧化碳生成中心代谢的（多碳）中间体。该循环的产物可作为合成细胞物质所有成分的前体。自养型二氧化碳固定在能量上成本高昂，因此毫不奇怪，在各类自养细菌中，该循环的运行受到严格的代谢控制。卡尔文循环中特有的两种酶，即磷酸核糖激酶和核酮糖-1,5-二磷酸羧化酶的合成，是通过终产物阻遏来调节的。在这种调控中，磷酸烯醇丙酮酸很可能具有警报素的功能。对从各种来源分离出的酶的研究表明，磷酸核糖激酶是通过调节现有酶活性来控制经由卡尔文循环的二氧化碳固定速率的靶标酶。一般来说，该酶被NADH强烈激活，而AMP和磷酸烯醇丙酮酸是有效的抑制剂。最近对真养产碱菌中磷酸核糖激酶的研究表明，这种酶也可能通过共价修饰来调节。
