Mn2+–DNA interactions in aqueous systems: A Raman spectroscopic study

Cristina M Muntean,Rolf Misselwitz,Heinz Welfle,Lubomir Dostál

doi:10.1155/2006/429147

Abstract

Interaction of natural calf thymus DNA with Mn2+ions was studied by means of Raman spectroscopy. Spectra of DNA in 10 mM Na-cacodylate buffer, pH 6.2, 10 mM NaCl and in buffer containing Mn2+ions were measured at room temperature. Mn2+concentrations varied between 0 and 0.6 M. DNA backbone conformational changes and DNA denaturation were not observed in the concentration range 0 and 0.5 M, however, DNA condensation was observed at a critical concentration of 100 mM Mn2+that prevented the measurement of Raman spectra. Binding of Mn2+to the charged phosphate groups of DNA is indicated in the spectra. A high affinity of Mn2+for guanine N7 was obvious, and binding to adenine was barely suggested.

Highlights

DNA–metal cation interactions and their effects on DNA structure have been investigated extensively by a variety of techniques [8,14,23], the mechanisms of the cation effects on the structure and physical properties of DNA have not yet been completely clarified [10]
A model for the interaction between manganese ions and DNA mediated by water was suggested, destabilizing the double helix and partially breaking the hydrogen bonds between the base pairs [21]. It has been shown by absorption and vibrational circular dichroism (VCD) spectroscopy, that Mn2+ ions induce at room temperature a B–Z transition of the synthetic oligonucleotide20 [2]
The experimental results shown above exemplify in detail the structural changes of calf thymus DNA induced by Mn2+ ions in the concentration range 0–600 mM

Summary

A Raman spectroscopic study

Cristina M. Muntean a,∗,∗∗, Rolf Misselwitz b, Lubomir Dostál b and Heinz Welfle b a National Institute of Research & Development for Isotopic and Molecular Technologies, PO 5, Box 700, R-400293 Cluj-Napoca, Romania b AG Biopolymerspektroskopie, Max-Delbrück-Centrum für Molekulare Medizin Berlin-Buch, Robert-Rössle-Str. 10, D-13092 Berlin, Germany

Introduction

Preparation of DNA samples

Raman spectroscopy

Results and discussion

Conclusions