Stochastic bifurcation, slow fluctuations, and bistability as an origin of biochemical complexity
Stochastic bifurcation, slow fluctuations, and bistability as an origin of biochemical complexity
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DOI：
10.1039/b900335p
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发表时间：
2009-01-01
影响因子：
3.3
通讯作者：
Xing, Jianhua
中科院分区：
文献类型：
--
作者：
Qian, Hong;Shi, Pei-Zhe;Xing, Jianhua
对于具有多时间尺度动力学的随机生化系统，我们提出了一个简单、统一的理论，这些系统在开放的化学环境中表现出噪声诱导的双稳态，而相应的宏观反应是不稳定的。这类非线性随机生化系统与经典的平衡态或近平衡态的系统有着根本的不同，后者的涨落遵循爱因斯坦-昂萨格-拉克斯-凯泽理论的单峰。结果表明，噪声引起的双稳态一般是由慢涨落引起的，随着涨落速率的减小，会出现干草分叉。由于详细的平衡，均衡分布必须与时间尺度的变化无关，因此分叉必然是一种驱动现象。作为例子，我们分析了目前感兴趣的三个生化网络：自我调节基因、随机二元决策和具有波动激酶的磷酸化-去磷酸化循环。讨论了双稳性对生物化学复杂性的影响。
We present a simple, unifying theory for stochastic biochemical systems with multiple time-scale dynamics that exhibit noise-induced bistability in an open-chemical environment, while the corresponding macroscopic reaction is unistable. Nonlinear stochastic biochemical systems like these are fundamentally different from classical systems in equilibrium or near-equilibrium steady state whose fluctuations are unimodal following Einstein-Onsager-Lax-Keizer theory. We show that noise-induced bistability in general arises from slow fluctuations, and a pitchfork bifurcation occurs as the rate of fluctuations decreases. Since an equilibrium distribution, due to detailed balance, has to be independent of changes in time-scale, the bifurcation is necessarily a driven phenomenon. As examples, we analyze three biochemical networks of currently interest: self-regulating gene, stochastic binary decision, and phosphorylation-dephosphorylation cycle with fluctuating kinase. The implications of bistability to biochemical complexity are discussed.