Dr Sara Szymkuć
Institute of Organic Chemistry PAS, Allchemy Inc
Title: “Synthetic connectivity and emergence in the network of prebiotic chemistry”
Seminarium on-line (link)
Nearly seventy years have passed since the famous Urey-Miller experiment demonstrating that simple abiotic species can be transformed into building blocks of living matter. Since then many other prebiotically plausible reactions have been validated. Yet the knowledge of how individual transformations combine into complex networks of interlacing systems and give rise to complex molecules is still fragmentary and leaves many questions unanswered.
We attacked this issue with the power of modern computer-assisted organic chemistry. Commencing with six simple molecules, generally accepted as feedstocks available on primordial Earth: H2O,NH3,H2S,HCN,CH4,N2 we created a network of tens of thousands of molecules synthesizable under prebiotic conditions. The key element here was to encode the body of prebiotic reactions in a form processable by a machine, including details of reactivity conflicts and reaction conditions. Then, these transformations were iteratively applied to a collection of six basic substrates. The network thus generated was analyzed to trace synthetic pathways leading to prebiotically relevant compounds as well as to map the first systems, in particular, reaction cycles.
In a recent Science (1) publication, we showed that the network comprises more abiotic molecules than biotic ones. The biotic compounds have distinct properties: they are more hydrophilic, more thermodynamically stable, have more balanced ratios of hydrogen donors to hydrogen acceptors. The synthetic routes leading to these biotic molecules are characterized by fewer changes of conditions along the pathways. Within the network, we identified not only all known prebiotic syntheses of biotic compounds but also other, previously unknown pathways, many of which we validated by experiment.
Perhaps the most impactful part of our findings was demonstration of three forms of chemical emergence: i) that molecules created within the network can enable new types of reactions ii) that simple chemical systems are reachable just in few steps from basic prebiotic feedstock iii) that first surfactants important for biologic compartmentalization are makeable from basic prebiotic feedstocks.
 A. Wołos, R. Roszak, A. Żądło-Dobrowolska, W. Beker, B. Mikulak-Klucznik, G. Spólnik, M. Dygas, S. Szymkuć, B. A. Grzybowski, Science2020.