|
| << vorige | volgende >> |
Tijdschrift beschrijving
Alle jaargangen van het bijbehorende tijdschrift
Alle afleveringen van het bijbehorende jaargang
Alle artikelen van de bijbehorende aflevering
Details van artikel 79 van 116 gevonden artikelen
| Titel: |
SALT DEPENDENCE OF BINDING OF Δ- and Λ-Ru(2, 2'-bypyridine)2ppz ( 2) AND A CHIRAGEN ANALOG WITH CALF THYMUS DNA: UNPREDICTIBILITY OF ENANTIOSELECTIVE BINDING TO DNA |
| Auteur: |
Strekas, Thomas C. Baker, A. David Zaltsman, Lyudmila Wang, Sihe |
| Verschenen in: |
Journal of coordination chemistry |
| Paginering: | Jaargang 39 (1996) nr. 3-4 pagina's 281-291 |
| Jaar: |
1996-11-01 |
| Inhoud: |
Fluorescence techniques have been used to measure binding constants with calf thymus DNA for both enantiomers of Ru(bpy)2ppz(+2) as well as a (+)-chiragen[6] complex of ruthenium(II) of Δ configuration, which has ppz as a third ligand. The configuration of the more strongly binding enantiomer of Ru(bpy)2ppz(+2) is unambiguously assigned as Λ (and not Δ as previously assumed), by comparison of the circular dichroism spectrum of the (+)-chiragen[6] complex of ruthenium(II) with ppz to the CD spectra of the bipyridine complexes. This assignment is also consistent with exciton theory of the circular dichroism spectra of such complexes. Binding constants for each enantiomer as well as the (+)-chiragen[6] complex are reported, and serve to quantitate the chiral discrimination of binding to DNA. Analysis of the sodium ion concentration dependence of the binding constants using polyelectrolyte theory indicates that the binding is largely electrostatic in nature. The non-electrostatic contribution (Kt°) at 50 mM Na+ is about 3.5% for both isomers and 5.3% for the (+)-chiragen[6] complex. Similar values have been reported for the enantiomers of Ru(phen)3(+2). The approximately four-fold difference in binding between the enantiomers and favoring the Λ (not the Δ) enantiomer reported here must therefore be attributed to differences in structural interaction which are non-electrostatic in nature. Clearly, the configuration of the two ancilliary ligands is not sufficient to predict which enantiomer will bind more strongly, as has been suggested. More subtle interactions with the double strandedB-form DNA structure, involving not only the ancilliary ligands, but also the partially intercalated diimine ligand, are clearly involved. |
| Uitgever: |
Taylor & Francis |
| Bronbestand: |
Elektronische Wetenschappelijke Tijdschriften |
Details van artikel 79 van 116 gevonden artikelen
| << vorige | volgende >> |