title: DNA homoduplexes containing no pyrimidine nucleotide.
abstract: We show using polyacrylamide gel electrophoresis that guanine+adenine repeat strands of DNA associate into homoduplexes at neutral pH and moderate ionic strength. The homoduplexes melt in a cooperative way like the Watson-Crick duplex, although they contain no Watson-Crick base pair. Guanine is absolutely needed for the homoduplex formation and the homoduplex stability increases with the guanine content of the repeat. The present results have implications for the nature of the first replicators, as well as regarding forces stabilizing the duplexes of DNA.
authors.affiliation: Institute of Biophysics, Academy of Sciences of the Czech Republic, Královopolská 135, 61265 Brno, Czech Republic. kypr@ibp.cz
authors.forename: Jaroslav
authors.initials: J
authors.lastname: Kypr
authors.forename: Iva
authors.initials: I
authors.lastname: Kejnovská
authors.forename: Michaela
authors.initials: M
authors.lastname: Vorlícková
mesh_terms: D000225:Adenine / Q000737:chemistry*; D020029:Base Pairing; D002942:Circular Dichroism; D004247:DNA / Q000737:chemistry; D004591:Electrophoresis, Polyacrylamide Gel / Q000379:methods*; D006147:Guanine / Q000737:chemistry*; D009690:Nucleic Acid Conformation; D009711:Nucleotides / Q000737:chemistry; D009841:Oligonucleotides / Q000737:chemistry*; D011743:Pyrimidines / Q000737:chemistry; D020080:Tandem Repeat Sequences; D013696:Temperature
chemical_list: D009711:Nucleotides; D009841:Oligonucleotides; D011743:Pyrimidines; D006147:Guanine; D004247:DNA; D000225:Adenine; C030986:pyrimidine