Smith Joshua I, Steel Mike, Hordijk Wim
Biomathematics Research Centre, Department of Mathematics and Statistics, University of Canterbury, Christchurch, New Zealand.
SmartAnalytiX.com, Lausanne, Switzerland.
J Syst Chem. 2014 Mar 3;5(1):2. doi: 10.1186/1759-2208-5-2. eCollection 2014.
In previous work, RAF theory has been developed as a tool for making theoretical progress on the origin of life question, providing insight into the structure and occurrence of self-sustaining and collectively autocatalytic sets within catalytic polymer networks. We present here an extension in which there are two "independent" polymer sets, where catalysis occurs within and between the sets, but there are no reactions combining polymers from both sets. Such an extension reflects the interaction between nucleic acids and peptides observed in modern cells and proposed forms of early life.
We present theoretical work and simulations which suggest that the occurrence of autocatalytic sets is robust to the partitioned structure of the network. We also show that autocatalytic sets remain likely even when the molecules in the system are not polymers, and a low level of inhibition is present. Finally, we present a kinetic extension which assigns a rate to each reaction in the system, and show that identifying autocatalytic sets within such a system is an NP-complete problem.
Recent experimental work has challenged the necessity of an RNA world by suggesting that peptide-nucleic acid interactions occurred early in chemical evolution. The present work indicates that such a peptide-RNA world could support the spontaneous development of autocatalytic sets and is thus a feasible alternative worthy of investigation.
在之前的工作中，RAF理论已被发展成为一种工具，用于在生命起源问题上取得理论进展，为催化聚合物网络中自我维持且集体自催化集的结构和出现提供见解。我们在此展示一种扩展情况，即存在两个“独立”的聚合物集，催化作用在集内和集间发生，但不存在将两个集的聚合物结合起来的反应。这种扩展反映了现代细胞中观察到的核酸与肽之间的相互作用以及早期生命的推测形式。
我们展示了理论工作和模拟，其表明自催化集的出现对于网络的分区结构具有鲁棒性。我们还表明，即使系统中的分子不是聚合物且存在低水平抑制时，自催化集仍有可能出现。最后，我们展示了一种动力学扩展，为系统中的每个反应赋予一个速率，并表明在这样一个系统中识别自催化集是一个NP完全问题。
最近的实验工作通过表明肽 - 核酸相互作用在化学进化早期就已发生，对RNA世界的必要性提出了挑战。目前的工作表明，这样一个肽 - RNA世界能够支持自催化集的自发发展，因此是一个值得研究的可行替代方案。
