Although it is well-known that the environment of mitochondria is a densely packed network of macromolecules, the kinetics of the essential metabolic enzyme, citrate synthase, has been studied only under dilute conditions. To understand how this crowded environment impacts the behavior of citrate synthase, Michaelis-Menten kinetics were measured spectrophotometrically in the presence of synthetic crowders as a function of size, concentration, and identity. The largest factor contributing to crowding effects was the overlap concentration (c*), the concentration above which polymers begin to interact. The presence of the crowder dextran decreased the maximum rate of the reaction by ∼20% in the dilute regime (c*) regardless of polymer size. The disparate effects observed from different crowding agents of similar size also reveal the importance of transient interactions from crowding.

中文翻译：

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重叠浓度和大分子拥挤对柠檬酸合酶活性的影响。

尽管众所周知，线粒体的环境是大分子的密集网络，但仅在稀稀条件下研究了必需的代谢酶柠檬酸合酶的动力学。为了了解这种拥挤的环境如何影响柠檬酸合酶的行为，在存在合成拥挤物的情况下，通过分光光度法对米氏反应动力学进行了测量，该动力学是尺寸，浓度和特性的函数。导致拥挤效应的最大因素是重叠浓度（c *），高于该浓度聚合物开始相互作用。稀溶液中拥挤右旋糖酐的存在使最大反应速率降低了约20％（c *）与聚合物尺寸无关。从相似大小的不同拥挤剂观察到的不同效果也揭示了拥挤产生短暂相互作用的重要性。