Autocatalytic binary polymer model (Vol. 45 No.5-6)

(a) The reaction scheme. (b) A typical reaction network.

Template directed replication of information in polymers is at the essence of living beings, and is believed to be a cornerstone of life's origin. Using a binary polymer model, where polymers act as templates for their autocatalytic replication, we analyze the chemical reaction network in which replicators serve as reactants of each other and compete for common resources. The involved random ligation, degradation and autocatalytic replication reactions are shown in figure (a). Our idealized model demonstrates how autocatalysis in such a molecular ecology completely alters the qualitative and quantitative system dynamics in counter-intuitive ways. We demonstrate analytically that the system features a stationary state where the concentration of polymers does not decrease with length. Numerical simulations reveal a strong intrinsic selection mechanism that favors the appearance of few population structures with highly ordered sequence patterns when starting from a pool of monomers. An example of such a cooperative structure is shown in figure (b). This selection mechanism is due to symmetries in the underlying reaction network, and we discuss how these intrinsically selected species might be in line or in conflict with other prebiotic selection mechanisms.

S. Tanaka, H. Fellermann and S. Rasmussen, "Structure and selection in an autocatalytic binary polymer model", EPL, 107, 28004 (2014)