Mitochondria is a decisive organelle of cells that produces adenosine triphosphate (ATP) by the process of oxidative phosphorylation of the Krebs cycle and the electron transport chain. The electron transport chain system of mitochondria embodies multiple enzyme supercomplexes including complex I to V which located in the inner membrane. Although the simple enzyme activity of some as-isolated complex has been studied so far, the steady-state kinetic analysis of each complex within the form of mitochondrial supercomplex has not been studied in depth. To this end, kinetic parameters of mitochondrial complex I–IV were determined using steady-kinetic analysis using corresponding substrates of them. Catalytic activity and binding affinity between substrates and enzymes were obtained by fitting the data to the Michaelis–Menten equation. Acquired kinetic parameters represented distinctive values depending on the complexes that can be interpreted by the characteristics of the enzymes including the distinction of substrates or the ratio of the enzyme itself under the supercomplex form. The indirect kcat of the mitochondrial enzymes were varied from 0.0609 to 0.334 s−1 in order of complex III, II, I, and IV and Km of substrates were also diverse from 5.1 μM to 12.14 mM. This is the first attempt to get exact kinetic values that should provide profound information to evaluate the mitochondrial function practically in advance.

中文翻译：

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牛心线粒体线粒体呼吸酶的稳态动力学分析

线粒体是细胞的决定性细胞器，它通过三羧酸循环和电子传递链的氧化磷酸化过程产生三磷酸腺苷 (ATP)。线粒体的电子传递链系统包含多种酶超复合物，包括位于内膜的复合物 I 至 V。虽然到目前为止已经研究了一些分离的复合物的简单酶活性，但尚未深入研究线粒体超复合物形式的每种复合物的稳态动力学分析。为此，线粒体复合物 I-IV 的动力学参数使用它们的相应底物通过稳态动力学分析来确定。通过将数据拟合到 Michaelis-Menten 方程，获得了底物和酶之间的催化活性和结合亲和力。获得的动力学参数代表不同的值，这取决于复合物，这些值可以通过酶的特征来解释，包括底物的区别或超复合物形式下酶本身的比例。线粒体酶的间接 kcat 从 0.0609 到 0.334 s-1 按复合物 III、II、I 和 IV 的顺序变化，底物的 Km 也从 5.1 μM 到 12.14 mM 不等。这是获得精确动力学值的第一次尝试，这些值应该提供深刻的信息，以实际提前评估线粒体功能。线粒体酶的间接 kcat 从 0.0609 到 0.334 s-1 按复合物 III、II、I 和 IV 的顺序变化，底物的 Km 也从 5.1 μM 到 12.14 mM 不等。这是获得精确动力学值的第一次尝试，这些值应该提供深刻的信息，以实际提前评估线粒体功能。线粒体酶的间接 kcat 从 0.0609 到 0.334 s-1 按复合物 III、II、I 和 IV 的顺序变化，底物的 Km 也从 5.1 μM 到 12.14 mM 不等。这是获得精确动力学值的第一次尝试，这些值应该提供深刻的信息，以实际提前评估线粒体功能。