Selection between Competing Self-Reproducing Lipids: Succession and Dynamic Activation

Abstract

Models of chemical evolution are central to advancing origins of life research. To design more lifelike systems, we must expand our understanding of molecular selection mechanisms. Here, we show two selection modes that produce evolving populations of self-reproducing species, formed through thiol–disulfide exchange. Competition between thiol precursors can give clear succession patterns based on steric factors, an intrinsic property. A separate, emergent selection mechanism—dynamic activating metathesis—was found when exploring competing disulfide precursors. These experiments reveal that additional species generated in the mixture open up alternative reaction pathways to form self-reproducing products. Thus, increased compositional complexity provides certain species with a unique competitive advantage at the expense of others.

Dissipative Dynamic Libraries (DDLs) and Dissipative Dynamic Combinatorial Chemistry (DDCC)

“…A very sophisticated DDL was ingeniously devised by Fletcher and coworkers [25] . However, before illustrating such DDL, it is helpful to understand how the single kinetic cycle works [26] .…”

“…Among the many competitive experiments reported by Fletcher et al, [25] two types of DDLs are worth considering here. The first one is obtained by the competition between sterically differentiated hydrophobic thiols 4 a – 4 c toward the disulfide 7 a (Figure 7a), whereas the second one is obtained by the competition of the hydrophobic thiol 4 a for the electronically differentiated disulfides 7 a – 7 c (Figure 7c).…”

“…A very sophisticated DDL was ingeniously devised by Fletcher and coworkers. [25] However, before illustrating such DDL, it is helpful to understand how the single kinetic cycle works. [26] The fuel reaction, providing the driving force for the reaction cycle, consists of the hydrogen peroxide (the fuel) oxidation of the phase separated hydrophobic octanethiol 4 a (the deactivating reactant) to yield 1,2-dioctyldisulfane 5 a (the waste).…”

Light-Fueled Primitive Replication and Selection in Biomimetic Chemical Systems

“…Chemical − or light energy , can promote chemical replication by producing precursors in a protometabolic manner. Molecular complexification and selection phenomena have been demonstrated by driving replication and decomposition with chemical energy in a kinetically asymmetric manner. However, a current challenge is simultaneously driving replication and replicator decomposition with external light energy.…”

Anion-assisted amidinium exchange and metathesis

“…34,[36][37][38][39] This type of DCR has been widely used in numerous fields including the synthesis of polymers as well as advanced molecular architectures and the exploration of complex chemical systems. 1,[40][41][42][43][44] Therefore, we decided to test if N,N 0disubstituted formamidinium ions were able to undergo formal metathesis. ‡ To our delight, the reaction between 1aa and 1bb did take place and afforded the metathesis product 1ab (Fig.…”