Cation and sequence effects on stability of intermolecular pyrimidine-purine-purine triplex.

AUTOR(ES)

Malkov, V A

RESUMO

A differential effect is found of various bivalent cations (Ba2+, Ca2+, Mg2+, Cd2+, Co2+, Mn2+, Ni2+, Zn2+ and Hg2+) on stability of intermolecular Py-Pu-Pu triplex with different sequence of base triads. Ca2+, Mg2+, Cd2+, Co2+, Mn2+, Ni2+ and Zn2+ do stabilize the d(C)n d(G)n d(G)n triplex whereas Ba2+ and Hg2+ do not. Ba2+, Ca2+, Mg2+ and Hg2+ destabilize the d(TC)n d(GA)n d(AG)n triplex whereas Cd2+, Co2+, Mn2+, Ni2+ and Zn2+ stabilize it. The complexes we observe are rather stable because they do not dissociate during time of gel electrophoresis in the co-migration experiments. Chemical probing experiments with dimethyl sulfate as a probe indicate that an arbitrary homopurine-homopyrimidine sequence forms triplex with corresponding purine oligonucleotide in the presence of Mn2+ or Zn2+, but not Mg2+. In the complex the purine oligonucleotide has antiparallel orientation with respect to the purine strand of the duplex. Specifically, we have shown the formation of the Py-Pu-Pu triplex in a fragment of human papilloma virus HPV-16 in the presence of Mn2+.

Documentos Relacionados

• Protonated pyrimidine-purine-purine triplex.
• Monovalent cation effects on intermolecular purine-purine-pyrimidine triple-helix formation.
• Oligodeoxyribonucleotide length and sequence effects on intermolecular purine-purine-pyrimidine triple-helix formation.
• The integral divalent cation within the intermolecular purine*purine. pyrimidine structure: a variable determinant of the potential for and characteristics of the triple helical association.
• Triplex formation with alpha anomers of purine-rich and pyrimidine-rich oligodeoxynucleotides.