Abstract EANA2026-7

Periodic temperature variations can power chemical heat engines in accordance with the generalized Carnot principle. Such systems are commonly found in developing reaction networks or RNA evolution. Based on a given balanced reaction equilibrium, they absorb heat at higher temperatures and release it at lower temperatures. The difference between the two heat quantities is converted into chemical energy, which is partially conserved due to the slow kinetics at lower temperatures. Subsequent steps can then use this energy to drive uphill reactions.

For example, the effect of periodic temperature variation on RNA interactions is demonstrated using pairs of competing RNA duplexes as a simplified model system. These represent random base-pairing interactions between short RNA chains at the earliest stages of RNA evolution. The molecular interaction kinetics are simulated based on experimental thermodynamic data obtained by M. E. Christiansen et al. and the Eyring theory. The simulated time developments demonstrate the impact of shifting reaction kinetics and a state of continuous non-equilibrium. The product mixture that forms slowly at low temperatures releases chemical energy quickly at high temperatures, while the product mixture that forms quickly at high temperatures releases chemical energy slowly at low temperatures. In terms of heat flow and energy storage, the chosen model system represents a generalized Carnot engine, as would most similar reactions during RNA evolution. This provides a perpetual driving force for selection processes and creates ideal conditions for ongoing molecular evolution.