Thermodynamic Potential for the Abiotic Synthesis of Adenine, Cytosine, Guanine, Thymine, Uracil, Ribose, and Deoxyribose in Hydrothermal Systems

Abstract

The thermodynamic potential for the abiotic synthesis of the five common nucleobases (adenine, cytosine, guanine, thymine, and uracil) and two monosaccharides (ribose and deoxyribose) from formaldehyde and hydrogen cyanide has been quantified under temperature, pressure, and bulk composition conditions that are representative of hydrothermal systems. The activities of the precursor molecules (formaldehyde and hydrogen cyanide) required to evaluate the thermodynamics of biomolecule synthesis were computed using the concentrations of aqueous N2, CO, CO2 and H2 reported in the modern Rainbow hydrothermal system. The concentrations of precursor molecules that can be synthesized are strongly dependent on temperature with larger concentrations prevailing at lower temperatures. Similarly, the thermodynamic drive to synthesize nucleobases, ribose and deoxyribose varies considerably as a function of temperature: all of the biomolecules considered in this study are thermodynamically favored to be synthesized throughout the temperature range from 0 degrees C to between 150 degrees C and 250 degrees C, depending on the biomolecule. Furthermore, activity diagrams have been generated to illustrate that activities in the range of 10(-2)- 10(-6) for nucleobases, ribose and deoxyribose can be in equilibrium with a range of precursor molecule activities at 150 degrees C and 500 bars. The results presented here support the notion that hydrothermal systems could have played a fundamental role in the origin of life, and can be used to plan and constrain experimental investigation of the abiotic synthesis of nucleic-acid related biomolecules.

The energetics of anabolism in natural settings

“…This is substantiated by Amend et al (2011), who show that the optimal conditions for synthesizing biomolecules because of mixing of cold seawater and 12 hydrothermal fluids is between 11.2 and 32°C. Similarly, LaRowe and Regnier (2008) showed that abiotic nucleotide synthesis is thermodynamically possible at low temperatures. Even the polymerization of amino acids into polypeptides is more favored at lower temperature (Amend et al 2013 and Figure 1) compared with higher ones.…”

“…Because the Gibbs energy of all chemical reactions is a function of temperature, pressure and composition, determining the energetic limits of anabolism will differ depending on these environmental variables (for example, Shock, 1998, 2000;McCollom and Amend, 2005;LaRowe and Regnier, 2008;Amend and McCollom, 2009;Amend et al, 2011Amend et al, , 2013LaRowe and Amend, 2014;Osburn et al, 2014;Teske et al, 2014;Price et al, 2015). In addition, the amount of energy that it takes to produce and sustain a given number of microorganisms depends on the mass of cells and the relative proportion of biomolecule types that make up these cells.…”

Thermodynamic dissipation theory for the origin of life

“…Prevailing scenarios for the origin of life center on the replication first "RNA World" (Gilbert, 1986) hypothesis (see Orgel, 2004, andRauchfuss, 2008, for a review), and "metabolism first" followed by replication proposals (see Shapiro, 2007, for a review) including hydrothermal vent proposals (Wächtershäuser, 2006;LaRowe and Regnier, 2008;Nitschke and Russell, 2009). The scenario presented here is more akin to the RNA World hypothesis but shares with the metabolism first theories the idea of a gradual genetic take-over of a metabolic process.…”

Study of Polymer Material Aging by Laser Mass Spectrometry, UV-Visible Spectroscopy, and Environmental Scanning Electron Microscopy

“…The simple molecules H 2 O, H 2 , CO 2 , CH 4 , would be present as a consequence of mineral reactions of the terrestrial peridotites with seawater and, with the N 2 of the environment and with an activation source such as gamma rays, they could form the simple organic molecules of biological relevance [48][49][50]22,51 and Ref. therein].…”