Origins of life and evolution of the biosphere

, Volume 31, Issue 3, pp 221–229

Concentration by Evaporation and the Prebiotic Synthesis of Cytosine


  • Kevin E. Nelson
    • Department of BiochemistryUniversity of Illinois at Urbana-Champaign
  • Michael P. Robertson
    • Department of Molecular BiologyThe University of Texas at Austin
  • Matthew Levy
    • Department of Molecular BiologyThe University of Texas at Austin
  • Stanley L. Miller
    • Department of Chemistry and BiochemistryUniversity of California

DOI: 10.1023/A:1010652418557

Cite this article as:
Nelson, K.E., Robertson, M.P., Levy, M. et al. Orig Life Evol Biosph (2001) 31: 221. doi:10.1023/A:1010652418557


The efficient prebiotic synthesis of cytosine from urea andcyanoacetaldehyde (CA) has recently been claimed to be invalidon the basis of possible side reactions of the starting materials and the inapplicability of prebiotic syntheses usingdrying beach conditions. We therefore have investigated the synthesis of cytosine and uracil from urea and cyanoacetaldehydeat 100 °C under dry-down conditions, and in solution at 4 °C and -20 °C. We find that cytosine isproduced from the low temperature experiments more efficientlythan calculated from the Arrhenius extrapolation from highertemperatures, i.e., 60-120 °C. In addition, we findthat CA dimer is as efficient as the monomer in cytosine synthesis. We also studied whether evaporating very dilutesolutions of nonvolatile organic compounds will concentrateaccording to theory. Solutions as dilute as 10-4 M concentrate from pure water approximately according to theory.Similar solutions in 0.5 M NaCl have less than theoreticalconcentrations due to absorption, but concentrations neardryness were very high.

cyanoacetaldehydecyanoacetaldehyde dimercytosinedry-down conditionsevaporationprebiotic synthesisuracil

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© Kluwer Academic Publishers 2001