Molecular features of Co-III tetra- and pentammines affect their influenceon DNA structure

Citation
A. Rodger et al., Molecular features of Co-III tetra- and pentammines affect their influenceon DNA structure, EUR J INORG, (9), 2001, pp. 2311-2316
Citations number
21
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Inorganic & Nuclear Chemistry
Journal title
EUROPEAN JOURNAL OF INORGANIC CHEMISTRY
ISSN journal
1434-1948 → ACNP
Issue
9
Year of publication
2001
Pages
2311 - 2316
Database
ISI
SICI code
1434-1948(200109):9<2311:MFOCTA>2.0.ZU;2-4
Abstract
The polyamines spermine and spermidine cause a range of structural effects on DNA. [Co(NH3)(6)](3+) is known to mimic many of these effects and we hav e shown previously that (+)[Co(en)(3)](3+) and (-)-[Co(en)(3)](3+) (en = et hylenediamine) do so as well. In this paper the effects of mono- and disubs titution of the Coin ammines by aqua, halo and nitro groups is explored. Th e overall effectiveness of the amines in conferring thermal stability on th e ct-DNA proceeds in the order: spermine > (+)-[Co(en)(3)](3+) approximate to (-)-[Co(en)(3)](3+) approximate to [Co(NH3)(6)](3+) spermidine > [Pt(NH3 )(4)](2+) > [Co(NH3)(5)H2O](3+) [Co(NH3)(5)Cl](2+) approximate to [Co(NH3)( 5)Br](2+) > cis-[Co(en)(2)NH3Cl](2+) > [Co(NH3)(5)(NO2)](2+) = trans-(Co(NH 3)(4)(H2O)(2)](3+); whereas the B -->Z transition-induction ordering is: sp ermine approximate to [Co(NH3)(6)](3+) > (+)-[Co(en)(3)](3+) = [Co(NH3)(5)( H2O)](3+) > (-)-[Co(en)(3)](3+) > [Co(NH3)(5)Br](2+) > [Co(NH3)(5)Cl](2+), with the other amines failing to cause the transition under the 11 mm salt concentration and temperature ramp conditions used; the DNA bending ranking is: spermine > [Co(NH3)(6)](3+) > (+)-[Co(en)(3)](3+) > (-)[Co(en)(3)](3+) > [Co(NH3)(5)(H2O)](3+) > trans-[Co(NH3)(4)(H2O)(2)](3+) > spermidine, wit h the other 2+ amines (the aquo complexes will be 2+ at neutral pH), especi ally the bromo and nitro compounds, having comparatively little effect. Whi le the presentation of NNN triangular faces is found to be important in the B -->Z transition, the fact that the halo ligands are probably substituted by the DNA phosphates plays a role, especially in the DNA bending, where d eep penetration of the major groove is concluded to be required. A favourab le interaction between the backbone and the aquo ligands may enhance the B -->Z transition.