title: Nonenzymatic template-directed synthesis on oligodeoxycytidylate sequences in hairpin oligonucleotides.
abstract: We have developed a novel method for studying template-directed synthesis in hairpin oligonucleotides.  An unpaired segment at the 5'-terminus of the hairpin acts as an intramolecular template for the extension of the paired 3'-terminus.  Products are analyzed by denaturing gel electrophoresis of [32P]-labeled hairpins.  Using this system, we have studied the synthesis of oligoguanylates on an oligodeoxycytidylate template.  We find that guanosine 5'-phosphoro(2-methyl)imidazolide adds efficiently to a terminal riboguanylate residue at temperatures in the range 0-37 degrees C but not at 50 degrees C.  At 0 degree C, the half-time for addition of the first G residue is about 3 h, and the reaction rate is independent of pH in the range 6.5-8.0.  The first addition reaction results in the formation of a predominantly 3'-5'-internucleotide bond.  When the 3'-terminal riboguanylate residue is placed by a deoxyguanylate residue, the half-time for the first addition increases from about 3 to about 30 h.
authors.affiliation: The Salk Institute for Biological Studies, San Diego, California 92186-8500, USA.
authors.forename: T
authors.initials: T
authors.lastname: Wu
authors.forename: L E
authors.initials: LE
authors.lastname: Orgel
mesh_terms: D001483:Base Sequence; D002851:Chromatography, High Pressure Liquid; D004591:Electrophoresis, Polyacrylamide Gel; D019143:Evolution, Molecular; D006863:Hydrogen-Ion Concentration; D008967:Molecular Biology / Q000379:methods*; D008969:Molecular Sequence Data; D009838:Oligodeoxyribonucleotides / Q000032:analysis* / Q000737:chemistry; D009841:Oligonucleotides / Q000032:analysis* / Q000737:chemistry; D011108:Polymers; D012265:Ribonucleotides / Q000032:analysis / Q000737:chemistry; D013698:Templates, Genetic
chemical_list: D009838:Oligodeoxyribonucleotides; D009841:Oligonucleotides; D011108:Polymers; D012265:Ribonucleotides; C033539:oligodeoxycytidylic acid