Viability Conditions for a Compartmentalized Protometabolic System: A Semi-Empirical Approach

In this work we attempt to find out the extent to which realistic prebiotic compartments, such as fatty acid vesicles, would constrain the chemical network dynamics that could have sustained a minimal form of metabolism. We combine experimental and simulation results to establish the conditions under which a reaction network with a catalytically closed organization (more specifically, an ()-system) would overcome the potential problem of self-suffocation that arises from the limited accessibility of nutrients to its internal reaction domain. The relationship between the permeability of the membrane, the lifetime of the key catalysts and their efficiency (reaction rate enhancement) turns out to be critical. In particular, we show how permeability values constrain the characteristic time scale of the bounded protometabolic processes. From this concrete and illustrative example we finally extend the discussion to a wider evolutionary context

Supramolecular systems chemistry

The field of supramolecular chemistry focuses on the non-covalent interactions between molecules that give rise to molecular recognition and self-assembly processes. Since most non-covalent interactions are relatively weak and form and break without significant activation barriers, many supramolecular systems are under thermodynamic control. Hence, traditionally, supra-molecular chemistry has focused predominantly on systems at equilibrium. However, more recently, self-assembly processes that are governed by kinetics, where the outcome of the assembly process is dictated by the assembly pathway rather than the free energy of the final assembled state, are becoming topical. Within the kinetic regime it is possible to distinguish between systems that reside in a kinetic trap and systems that are far from equilibrium and require a continuous supply of energy to maintain a stationary state. In particular, the latter systems have vast functional potential, as they allow, in principle, for more elaborate structural and functional diversity of self-assembled systems-indeed, life is a prime example of a far- from- -equilibrium system. In this Review, we compare the different thermodynamic regimes using some selected examples and discuss some of the challenges that need to be addressed when developing new functional supramolecular systems

Experimental evidences suggest high between-vesicle diversity of artificial vesicle populations: Results, models and implications

In the past years, artificial cellular models for origins-of-life research and synthetic biology have been extensively studied. At this aim, solute-filled lipid vesicles (liposomes) are widely used. Several evidences have been collected about the capture of water-soluble chemicals, the mechanism of vesicle self-reproduction, and the course of (bio)chemical reactions in the vesicle lumen. Among the several fascinating questions which emerged from these studies, here we focus on a peculiar feature, namely, the fact that a spontaneous heterogeneity of vesicle structure often emerges. In other words, vesicle populations created in the laboratory by classical batch methods include very ‘diverse’ vesicles with respect to size, morphology, and – importantly – solute content. The consequences of this between-vesicle diversity are shortly discussed