title: Prebiotic glycosylation of uracil with electron-donating substituents.
abstract: Following the suggestion that nucleoside analogues having their nucleobases joined to ribose via a carbon-carbon bond might easily arise prebiotically, the glycosylation of uracil carrying electron-donating substituents (Me, OH, OCH3, NH2) at its 5 or 6 positions was investigated. Of these, only 6-aminouracil gave glycosylated products in greater than 50% yield under simulated prebiotic conditions. The reaction provided four products, three of which were purified by preparative HPLC. The structure of the isolated compounds was determined by high-resolution mass spectrometry and NMR spectroscopy. The glycosylation products were, as expected, C-nucleosides, with the sugar having either a pyranose or a furanose structure, with the ratio depending on the precise conditions, implying reversible addition. Interestingly, the 6-aminouracil riboside displays two hydrogen bonding patterns, the "acceptor-donor-acceptor" pattern of uridine itself and (upon 180° rotation) the "acceptor-donor-donor" hydrogen bonding pattern. The second, in an artificially expanded genetic information system, is trivially called "V" and pairs with a purine analogue that presents the complementary "donor-acceptor-acceptor" hydrogen bonding pattern, trivially called "J."
authors: Foundation for Applied Molecular Evolution, The Westheimer Institute for Science and Technology , Alachua, Florida.
authors: Hyo-Joong
authors: HJ
authors: Kim
authors: Steven A
authors: SA
authors: Benner
mesh_terms: D002384:Catalysis; D002851:Chromatography, High Pressure Liquid; D004583:Electrons; D006031:Glycosylation; D006863:Hydrogen-Ion Concentration; D000069497:Origin of Life; D012266:Ribose / Q000737:chemistry; D014498:Uracil / Q000031:analogs & derivatives / Q000737:chemistry*
chemical_list: D014498:Uracil; D012266:Ribose; C013400:6-aminouracil