title: Accumulation of formamide in hydrothermal pores to form prebiotic nucleobases.
abstract: Formamide is one of the important compounds from which prebiotic molecules can be synthesized, provided that its concentration is sufficiently high. For nucleotides and short DNA strands, it has been shown that a high degree of accumulation in hydrothermal pores occurs, so that temperature gradients might play a role in the origin of life [Baaske P, et al. (2007)Proc Natl Acad Sci USA104(22):9346-9351]. We show that the same combination of thermophoresis and convection in hydrothermal pores leads to accumulation of formamide up to concentrations where nucleobases are formed. The thermophoretic properties of aqueous formamide solutions are studied by means of Infrared Thermal Diffusion Forced Rayleigh Scattering. These data are used in numerical finite element calculations in hydrothermal pores for various initial concentrations, ambient temperatures, and pore sizes. The high degree of formamide accumulation is due to an unusual temperature and concentration dependence of the thermophoretic behavior of formamide. The accumulation fold in part of the pores increases strongly with increasing aspect ratio of the pores, and saturates to highly concentrated aqueous formamide solutions of ∼85 wt% at large aspect ratios. Time-dependent studies show that these high concentrations are reached after 45-90 d, starting with an initial formamide weight fraction of[Formula: see text]wt % that is typical for concentrations in shallow lakes on early Earth.
authors.affiliation: Institute of Complex Systems-3 Soft Condensed Matter, Forschungszentrum Juelich GmbH, D-52428 Juelich, Germany;
authors.forename: Doreen
authors.initials: D
authors.lastname: Niether
authors.affiliation: Institute of Complex Systems-3 Soft Condensed Matter, Forschungszentrum Juelich GmbH, D-52428 Juelich, Germany;
authors.forename: Dzmitry
authors.initials: D
authors.lastname: Afanasenkau
authors.affiliation: Institute of Complex Systems-3 Soft Condensed Matter, Forschungszentrum Juelich GmbH, D-52428 Juelich, Germany; Department of Physics, Heinrich-Heine-Universitaet Duesseldorf, D-40225 Dusseldorf, Germany;
authors.forename: Jan K G
authors.initials: JK
authors.lastname: Dhont
authors.affiliation: Institute of Complex Systems-3 Soft Condensed Matter, Forschungszentrum Juelich GmbH, D-52428 Juelich, Germany; Department für Chemie - Physikalische Chemie, Universitaet zu Koeln, 50939 Cologne, Germany s.wiegand@fz-juelich.de.
authors.forename: Simone
authors.identifier: http://orcid.org/0000-0001-6333-1956
authors.initials: S
authors.lastname: Wiegand
mesh_terms: D004247:DNA / Q000737:chemistry*; D005559:Formamides / Q000737:chemistry*; D060086:Hydrothermal Vents / Q000737:chemistry*; D009711:Nucleotides / Q000737:chemistry*; D000069497:Origin of Life
chemical_list: D005559:Formamides; D009711:Nucleotides; C031066:formamide; D004247:DNA
keywords: concentration problem; hydrothermal vents; molecular evolution; origin-of-life problem; thermophoresis