Neomycin, spermine and hexaamminecobalt (III) share common structural motifs in converting B- to A-DNA.
AUTOR(ES)
Robinson, H
RESUMO
The (dG)n.(dC)n-containing 34mer DNA duplex [d(A2G15C15T2)]2 can be effectively converted from the B-DNA to the A-DNA conformation by neomycin, spermine and Co(NH3)6(3+). Conversion is demonstrated by a characteristic red shift in the circular dichroism spectra and dramatic NMR spectral changes in chemical shifts. Additional support comes from the substantially stronger CH6/GH8-H3'NOE intensities of the ligand-DNA complexes than those from the native DNA duplex. Such changes are consistent with a deoxyribose pucker transition from the predominate C2'-endo (S-type) to the C3'-endo (N-type). The changes for all three ligand-DNA complexes are identical, suggesting that those three complex cations share common structural motifs for the B- to A-DNA conversion. The A-DNA structure of the 4:1 complex of Co(NH3)6(3+)/d(ACCCGCGGGT) has been analyzed by NOE-restrained refinement. The structural basis of the transition may be related to the closeness of the two negatively charged sugar-phosphate backbones along the major groove in A-DNA, which can be effectively neutralized by the multivalent positively charged amine functions of these ligands. In addition, ligands like spermine or Co(NH3)6(3+) can adhere to guanine bases in the deep major groove of the double helix, as is evident from the significant direct NOE cross-peaks from the protons of Co(NH3)6(3+) to GH8, GH1 (imino) and CH4 (amino) protons. Our results point to future directions in preparing more potent derivatives of Co(NH3)6(3+) for RNA binding or the induction of A-DNA.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=145680Documentos Relacionados
- Stereochemical model for proflavin intercalation in A-DNA.
- The molecular electrostatic potential and steric accessibility of A-DNA.
- Transmissible Resistance to Penicillin G, Neomycin, and Chloramphenicol in Rhizobium japonicum1
- Influence of counter-ions on the crystal structures of DNA decamers: binding of [Co(NH3)6]3+ and Ba2+ to A-DNA.
- Effects of base substituents on the hydration of B- and Z-DNA: correlations to the B- to Z-DNA transition.