"Prebiotic Synthesis of Autocatalytic Products from Formaldehyde-Derived Sugars as the Carbon and Energy Source"
In a general way, life could be described as a chemical process (metabolism-biopolymer synthesis) that is catalytically controlled by its products (proteins-nucleic acids) in a way that enhances the perpetuation of the entire system. From this perspective, the origin of life can be considered as a series of events in which a prebiotic chemical process became increasingly controlled by the catalytic action of its products in a way that facilitated self-perpetuation. This view stressing autocatalysis imposes three constraints on the chemical process responsible for the origin of life. The process must (a) yield autocatalytic products that accelerate their own synthesis, (b) be a 'one-pot’ process where proximity and containment allow catalytic products to act on chemical intermediates of the process, and (c) occur in the presence of liquid water needed for delivery of a primary organic substrate(s) from the environment. Furthermore, the process must have a favorable free energy, and a rate that is faster than the rate of loss of intermediates from the catalytic domain. The relevance of the process to biogenesis is strengthened if its chemistry resembles and thereby allows its straightforward development into modern metabolism. Based on these criteria, we currently believe that the most attractive process for the origin of life involves sugar chemistry, specifically the incorporation of formaldehyde and/or glycolaldehyde into acyclic sugars that then react with ammonia and/or hydrogen sulfide to generate a variety of autocatalytic products (amines, amino acids, imidazoles, thiols, and polymers). Therefore, we propose to investigate this chemical process named the Sugar Model in order to develop a better understanding of the chemical dynamics involved in the origin of life on the early Earth and elsewhere. This proposed model study of the origins process is aimed at (a), understanding how life begins and evolves by identifying the sources of simple chemicals that contribute to prebiotic evolution and the emergence of life, and (b) determining which chemical systems could have served as precursors of metabolic and replicating systems on Earth and elsewhere, including alternatives to the current DNA-RNA-protein basis for life.