title: Untemplated nonenzymatic polymerization of 3',5'cGMP: a plausible route to 3',5'-linked oligonucleotides in primordia.
abstract: The high-energy 3',5' phosphodiester linkages conserved in 3',5' cyclic GMPs offer a genuine solution for monomer activation required by the transphosphorylation reactions that could lead to the emergence of the first simple oligonucleotide sequences on the early Earth. In this work we provide an in-depth characterization of the effect of the reaction conditions on the yield of the polymerization reaction of 3',5' cyclic GMPs both in aqueous environment as well as under dehydrating conditions. We show that the threshold temperature of the polymerization is about 30 °C lower under dehydrating conditions than in solution. In addition, we present a plausible exergonic reaction pathway for the polymerization reaction, which involves transient formation of anionic centers at the O3' positions of the participating riboses. We suggest that excess Na(+) cations inhibit the polymerization reaction because they block the anionic mechanism via neutralizing the negatively charged O3'. Our experimental findings are compatible with a prebiotic scenario, where gradual desiccation of the environment could induce polymerization of 3',5' cyclic GMPs synthesized in liquid.
authors.affiliation: Institute of Biophysics, Academy of Sciences of the Czech Republic , Královopolská 135, CZ-61265 Brno, Czech Republic.
authors.forename: Judit E
authors.initials: JE
authors.lastname: Šponer
authors.forename: Jiří
authors.initials: J
authors.lastname: Šponer
authors.forename: Alessandra
authors.initials: A
authors.lastname: Giorgi
authors.forename: Ernesto
authors.initials: E
authors.lastname: Di Mauro
authors.forename: Samanta
authors.initials: S
authors.lastname: Pino
authors.forename: Giovanna
authors.initials: G
authors.lastname: Costanzo
mesh_terms: D005075:Biological Evolution; D002412:Cations / Q000737:chemistry; D006152:Cyclic GMP / Q000737:chemistry*; D008956:Models, Chemical; D009841:Oligonucleotides / Q000737:chemistry; D058105:Polymerization; D011789:Quantum Theory; D012965:Sodium Chloride / Q000737:chemistry; D012996:Solutions; D012997:Solvents / Q000737:chemistry; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013696:Temperature; D014867:Water / Q000737:chemistry
chemical_list: D002412:Cations; D009841:Oligonucleotides; D012996:Solutions; D012997:Solvents; D014867:Water; D012965:Sodium Chloride; D006152:Cyclic GMP