Issue 19, 2001

Isomer formation in the binding of [PtCl2(cis-cyclohexane-1,3-diamine)] to oligonucleotides and the X-ray crystal structure of [PtCl2(cis-cyclohexane-1,3-diamine)]·dimethylformamide

Abstract

The crystal structure of [PtCl2(cis-1,3-chxn)] (cis-1,3-chxn = (cis-cyclohexane-1,3-diamine)) as the dimethyformamide solvate is reported. When [PtCl2(cis-1,3-chxn)] binds to d(GpG), two isomers are formed that are readily separated by HPLC. Both the HPLC and GFAAS studies of the products show that the isomers form in a 1 ∶ 1 ratio. Competition experiments involving d(GpG) and the aquated and nonaquated forms of [PtCl2(cis-1,3-chxn)] and [PtCl2(NH3)2] showed that the slower binding of the former complex was due to slower aquation and not steric bulk. 1D and 2D NMR studies of the [Ptd(GpG)(cis-1,3-chxn)] isomers showed that both the dinucleotide and the diamine were highly fluxional, even at low temperatures, and this prevented formation of strong cross peaks in the NOESY and ROESY spectra and hence identification of the isomers. [PtCl2(cis-1,3-chxn)] was reacted with a 52-mer oligonucleotide having six GpG binding sites and the products were enzymatically digested and separated by HPLC. The two [Ptd(GpG)(cis-1,3-chxn)] stereoisomers were the only significant platinated products, again forming in a 1 ∶ 1 ratio although it had been anticipated that stereoselectivity would be observed in the reaction with the 52-mer because of the potential for steric interactions with the cis-1,3-chxn ligand. Molecular modelling revealed that the observed lack of stereoselectivity was due to the ability of the cis-1,3-chxn ligand to adopt a continuum of conformations that allow it to avoid severe steric clashes with the DNA.

Graphical abstract: Isomer formation in the binding of [PtCl2(cis-cyclohexane-1,3-diamine)] to oligonucleotides and the X-ray crystal structure of [PtCl2(cis-cyclohexane-1,3-diamine)]·dimethylformamide

Supplementary files

Article information

Article type
Paper
Submitted
22 May 2001
Accepted
14 Aug 2001
First published
13 Sep 2001

J. Chem. Soc., Dalton Trans., 2001, 2769-2774

Isomer formation in the binding of [PtCl2(cis-cyclohexane-1,3-diamine)] to oligonucleotides and the X-ray crystal structure of [PtCl2(cis-cyclohexane-1,3-diamine)]·dimethylformamide

S. T. Cham, C. I. Diakos, L. T. Ellis, R. R. Fenton, V. P. Munk, B. A. Messerle and T. W. Hambley, J. Chem. Soc., Dalton Trans., 2001, 2769 DOI: 10.1039/B104502B

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Spotlight

Advertisements