论文标题
精确减少尿素尿布反应中pH振荡的模型,仅限于巨型脂质囊泡
Accurate reduced models for the pH oscillations in the urea-urease reaction confined to giant lipid vesicles
论文作者
论文摘要
这项理论研究涉及基于局限于巨型脂质囊泡的尿素 - 尿液反应的pH振荡器。在适当的条件下,尿素和氢离子在单层囊泡膜上的差分转运会定期重置pH时钟,从而将系统从酸转换为碱性,从而导致自维持的振荡。我们分析了相流的结构和极限循环的结构,该结构控制着巨型囊泡的动力学,并在小囊泡大小的小囊泡中主导着明显的随机振荡。为此,我们得出了简化的模型,这些模型可与数值溶液补充的分析处理,并获得振荡的周期和幅度以及振荡行为持续存在的参数结构域。我们表明,这些预测的准确性对使用的还原方案高度敏感。特别是,我们建议使用准确的两变量模型,并显示其等于三变量模型,该模型接受了化学反应网络的解释。单个pH振荡器的忠实建模对于合理化实验和了解囊泡的交流和节奏同步似乎至关重要。
This theoretical study concerns a pH oscillator based on the urea-urease reaction confined to giant lipid vesicles. Under suitable conditions, differential transport of urea and hydrogen ion across the unilamellar vesicle membrane periodically resets the pH clock that switches the system from acid to basic, resulting in self-sustained oscillations. We analyse the structure of the phase flow and of the limit cycle, which controls the dynamics for giant vesicles and dominates the pronouncedly stochastic oscillations in small vesicles of submicrometer size. To this end, we derive reduced models, which are amenable to analytic treatments that are complemented by numerical solutions, and obtain the period and amplitude of the oscillations as well as the parameter domain, where oscillatory behavior persists. We show that the accuracy of these predictions is highly sensitive to the employed reduction scheme. In particular, we suggest an accurate two-variable model and show its equivalence to a three-variable model that admits an interpretation in terms of a chemical reaction network. The faithful modeling of a single pH oscillator appears crucial for rationalizing experiments and understanding communication of vesicles and synchronization of rhythms.