Prebiotic Origin of Pre‐RNA Building Blocks in a Urea “Warm Little Pond” Scenario

Abstract

Urea appears to be a key intermediate of important prebiotic synthetic pathways. Concentrated pools of urea likely existed on the surface of the early Earth, as urea is synthesized in significant quantities from hydrogen cyanide or cyanamide (widely accepted prebiotic molecules), it has extremely high water solubility, and it can concentrate to form eutectics from aqueous solutions. We propose a model for the origin of a variety of canonical and non‐canonical nucleobases, including some known to form supramolecular assemblies that contain Watson‐Crick‐like base pairs.The dual nucleophilic‐electrophilic character of urea makes it an ideal precursor for the formation of nitrogenous heterocycles. We propose a model for the origin of a variety of canonical and noncanonical nucleobases, including some known to form supramolecular assemblies that contain Watson‐Crick‐like base pairs. These reactions involve urea condensation with other prebiotic molecules (e. g., malonic acid) that could be driven by environmental cycles (e. g., freezing/thawing, drying/wetting). The resulting heterocycle assemblies are compatible with the formation of nucleosides and, possibly, the chemical evolution of molecular precursors to RNA. We show that urea eutectics at moderate temperature represent a robust prebiotic source of nitrogenous heterocycles. The simplicity of these pathways, and their independence from specific or rare geological events, support the idea of urea being of fundamental importance to the prebiotic chemistry that gave rise to life on Earth.

X-ray Fiber Diffraction and Computational Analyses of Stacked Hexads in Supramolecular Polymers: Insight into Self-Assembly in Water by Prospective Prebiotic Nucleobases

“…The QM and MD simulations show the importance of stacking interactions for the stability of these systems and support the conclusion that stacks of (TAP/Cy) 3 hexads have an unusually strong propensity to form helical structures . The computational studies support the recent conjecture that a small cavity between stacked hexads might be able to trap ions, similar to the central pore of G-tetrads. , The combined computational and experimental results provide insight into the macroscopic features exhibited by hexad assemblies and support the hypothesis that the unique self-assembly properties of BA, TAP, MA, and Cy, and their suspected prebiotic origin, make them strong candidate recognition units for the informational polymers of life before the emergence of RNA. ,− …”

A dual perspective on the microwave-assisted synthesis of HCN polymers towards the chemical evolution and design of functional materials

“…Beyond the nucleobases identified (uracil ( h9 ), adenine ( h15 ) and guanine ( h16 )), it is interesting to detect new triazines and pyrimidines, since recently cyanuric acid ( h5 ), barbituric acid ( h12 ), melamine and 2,4,6-triaminopyrimidine have been proposed as no canonical nucleobases in a pre-RNA world due to their capability to form ribonucleosides and supramolecular assemblies that are held by Watson–Crick type hydrogen-bonded base pairs. These heterocycles can be formed from cyanamide, its derivatives (malonic acid and urea) and AMN 49 , 50 . All of these N-heterocycle precursors are known to be formed from HCN 13 .…”

Horizontal gene transfer provides insights into the deep evolutionary history and biology of Trichinella

“…Additionally, ammonium cyanate can be generated from the decomposition of urea ( Dirnhuber and Schütz, 1948 ) where urea is also considered a key intermediate in prebiotic earth and a potential precursor of nitrogenous heterocycles and therefore nucleobases. ( Menor Salván et al, 2020 ; Nowakowska et al, 2006 ). Albeit toxic to cells, the importance of cyanate in earth's development and its availability as a timely biochemical substrate cannot be overstated.…”