Michaelis-Menten Equation and Detailed Balance in Enzymatic Networks
Michaelis-Menten Equation and Detailed Balance in Enzymatic Networks
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DOI：
10.1021/jp110924w
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发表时间：
2011-05-12
影响因子：
3.3
通讯作者：
Cao, Jianshu
中科院分区：
文献类型：
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作者：
Cao, Jianshu
生物化学中的许多酶促反应远比著名的米氏机制复杂得多，但观察到的周转率通常服从于底物浓度的双曲线依赖关系，这是几乎世纪前为简单的米氏机制建立的关系。为了解决这个长期存在的难题，我们应用通量平衡方法来预测复杂酶促反应的平均周转时间中底物依赖性的函数形式，并确定详细的平衡（即，缺乏不平衡的构象电流）作为米氏方程描述酶网络中周转率的底物浓度依赖性的充分条件。这一预测可以在单分子事件平均测量中使用最近提出的详细违反平衡的签名进行验证。这一发现有助于分析最近对酶网络的单分子研究，并可应用于其他外部变量，如力依赖性和电压依赖性。
Many enzymatic reactions in biochemistry are far more complex than the celebrated Michaelis-Menten scheme, but the observed turnover rate often obeys the hyperbolic dependence on the substrate concentration, a relation established almost a century ago for the simple Michaelis-Menten mechanism. To resolve the longstanding puzzle, we apply the flux balance method to predict the functional form of the substrate dependence in the mean turnover time of complex enzymatic reactions and identify detailed balance (i.e., the lack of unbalanced conformtional current) as a sufficient condition for the Michaelis Menten equation to describe the substrate concentration dependence of the turnover rate in an enzymatic network. This prediction can be verified in single-molecule event-averaged measurements using the recently proposed signatures of detailed balance violations. The finding helps analyze recent single-molecule studies of enzymatic networks and can be applied to other external variables, such as force-dependence and voltage-dependence.