title: Nonenzymatic oligomerization reactions on templates containing inosinic acid or diaminopurine nucleotide residues.
abstract: The template-directed oligomerization of nucleoside-5'-phosphoro-2-methyl imidazolides on standard oligonucleotide templates has been studied extensively. Here, we describe experiments with templates in which inosinic acid (I) is substituted for guanylic acid, or 2,6-diaminopurine nucleotide (D) for adenylic acid. We find that the substitution of I for G in a template is strongly inhibitory and prevents any incorporation of C into internal positions in the oligomeric products of the reaction. The substitution of D for A, on the contrary, leads to increased incorporation of U into the products. We found no evidence for the template-directed facilitation of oligomerization of A or I through A-I base pairing. The significance of these results for prebiotic chemistry is discussed.
authors.affiliation: The Salk Institute for Biological Studies, San Diego, CA 92186, USA.
authors.forename: I A
authors.initials: IA
authors.lastname: Kozlov
authors.forename: L E
authors.initials: LE
authors.lastname: Orgel
mesh_terms: D015075:2-Aminopurine / Q000031:analogs & derivatives* / Q000737:chemistry; D000225:Adenine / Q000737:chemistry; D000241:Adenosine / Q000737:chemistry; D000249:Adenosine Monophosphate / Q000031:analogs & derivatives / Q000737:chemistry; D020029:Base Pairing; D003568:Cytidine Monophosphate / Q000031:analogs & derivatives / Q000737:chemistry; D003596:Cytosine / Q000737:chemistry; D017931:DNA Primers; D019418:Evolution, Chemical; D019143:Evolution, Molecular; D018559:Exobiology; D006147:Guanine / Q000737:chemistry; D007291:Inosine Monophosphate / Q000737:chemistry*; D012313:RNA / Q000138:chemical synthesis*; D013698:Templates, Genetic; D014498:Uracil / Q000737:chemistry; D014542:Uridine Monophosphate / Q000031:analogs & derivatives / Q000737:chemistry
chemical_list: D017931:DNA Primers; D007291:Inosine Monophosphate; C041881:adenosine 5'-phospho-2-methylimidazolide; D000249:Adenosine Monophosphate; D015075:2-Aminopurine; C007300:2,6-diaminopurine; D014498:Uracil; D006147:Guanine; D012313:RNA; C057426:uridine 5'-phospho-2-methylimidazolide; C043331:cytidine 5'-phospho-2-methylimidazolide; D003596:Cytosine; D014542:Uridine Monophosphate; D003568:Cytidine Monophosphate; D000225:Adenine; D000241:Adenosine