Carbon fixation is the process by which CO2 is converted from a gas into biomass. The Calvin–Benson–Bassham cycle (CBB) is the dominant carbon-consuming pathway on Earth, driving >99.5% of the ∼120 billion tons of carbon that are converted to sugar by plants, algae, and cyanobacteria. The carboxylase enzyme in the CBB, ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco), fixes one CO2 molecule per turn of the cycle into bioavailable sugars. Despite being critical to the assimilation of carbon, rubisco's kinetic rate is not very fast, limiting flux through the pathway. This bottleneck presents a paradox: Why has rubisco not evolved to be a better catalyst? Many hypothesize that the catalytic mechanism of rubisco is subject to one or more trade-offs and that rubisco variants have been optimized for their native physiological environment. Here, we review the evolution and biochemistry of rubisco through the lens of structure and mechanism in order to understand what trade-offs limit its improvement. We also review the many attempts to improve rubisco itself and thereby promote plant growth.

中文翻译：

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Rubisco 功能、进化和工程

碳固定是二氧化碳被吸收的过程2从气体转化为生物质。卡尔文-本森-巴沙姆循环 (CBB) 是地球上主要的碳消耗途径，约 1200 亿吨碳中的 99.5% 以上由植物、藻类和蓝藻转化为糖。 CBB 中的羧化酶，核酮糖-1,5-二磷酸羧化酶/加氧酶 (rubisco)，可固定一个 CO2每轮循环将分子转化为生物可利用的糖。尽管对碳同化至关重要，但 Rubisco 的动力学速率并不是很快，限制了通过该途径的通量。这个瓶颈提出了一个悖论：为什么 Rubisco 没有进化成更好的催化剂？许多假设认为 Rubisco 的催化机制受到一种或多种权衡，并且 Rubisco 变体已针对其天然生理环境进行了优化。在这里，我们从结构和机制的角度回顾了 Rubisco 的进化和生物化学，以了解哪些权衡限制了其改进。我们还回顾了许多改进 rubisco 本身从而促进植物生长的尝试。