title: [Possibilities of forming a hydrogen-bonded cytosine-adenine pair in the structure of transfer ribonucleic acid and at the wobble-position of the codon-anticodon complex].
abstract: 220 nucleotide sequences of tRNAs were investigated to elucidate the frequency of appearance of C-A pairs in their main two-stranded regions, in the positions 26--44 and 15--48. It was supposed, that in the formation of C-A pairs on antiparallel polynucleotide chains the atomic groups--N4-H and -N3 of cytosine make up H-bonds with the groups N7- and H-N6--of adenine. On parallel chains, H-bonds, probably, form -N6-H and --N1 groups of adenine with N3- and H-N4--of cytosine. The calculation results predicted a significant energy of ineraction between cytosine and adenine. By the investigation of the molecular models it was shown that the formation of H-bonded C-A pairs requires considerable changes of conformation in rebosephosphate chains. In addition a theoretical analysis revealed the possibility of formation of C-A pairs at the wobble-position of codon-anticodon complex. The significance of this nucleotide pair in the processes of genetic coding proved to depend on the stability of the codon-anticodon complex, modification of cytosine 34 and structural features of the distant regions of the tRNA.
mesh_terms: D000225:Adenine; D000926:Anticodon; D001482:Base Composition; D001483:Base Sequence; D003062:Codon; D003596:Cytosine; D006860:Hydrogen Bonding; D008958:Models, Molecular; D009690:Nucleic Acid Conformation; D012333:RNA, Messenger; D012343:RNA, Transfer
chemical_list: D000926:Anticodon; D003062:Codon; D012333:RNA, Messenger; D003596:Cytosine; D012343:RNA, Transfer; D000225:Adenine
vernacular_title: O vozmozhnostiakh obrazovaniia vodorodno-sviazannoĭ pary tsitozin-adenin v strukture transportnoĭ ribonukleinovoĭ kisloty i Wobble-pozitsii kodon-antikodonovogo kompleksa.