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Spectroscopy
Volume 20 (2006), Issue 5-6, Pages 261-268
http://dx.doi.org/10.1155/2006/219603

The Influence of Mn2+ on DNA structure in the presence of Na+ ions: A Raman spectroscopic study

Cristina M. Muntean,1,3 Rolf Misselwitz,2,4 and Heinz Welfle2

1National Institute of Research & Development for Isotopic and Molecular Technologies, P.O. 5, Box 700, R-400293 Cluj-Napoca, Romania
2Max-Delbrück-Centrum für Molekulare Medizin Berlin-Buch, Robert-Rössle-Str. 10, D-13092 Berlin, Germany
3The Max-Delbrück-Centrum für Molekulare Medizin Berlin-Buch, Robert-Rössle-Str. 10, D-13092 Berlin, Germany
4Institut für Immungenetik, Charite-Universitätsmedizin Berlin, Campus Virchow-Klinikum, Humboldt-Universität zu Berlin, Spandauer Damm 130, 14050 Berlin, Germany

Copyright © 2006 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The influence of Mn2+ ions on the structure of natural calf thymus DNA was studied by Raman spectroscopy. Measurements were done at room temperature and pH 6.2±0.2, in the presence of the physiological concentration of 150 mM Na+ ions, and in the presence of Mn2+ concentrations that varied between 0 and 600 mM. No condensation of DNA was observed at any of the Mn2+ concentrations. At 5 mM Mn2+ and 150 mM Na+ no significant influence of Mn2+ ions on the DNA structure can be observed. Compared with our previous results obtained at 10 mM Na+ ions, binding of Mn2+ ions to charged phosphate groups and to DNA bases is inhibited in the presence of 150 mM Na+ ions. DNA backbone conformational changes were not observed in the whole concentration range of Mn2+ ions as judging from the Raman spectra. No evidence for DNA melting was identified. A high Mn2+ affinity for binding to guanine N7 and possibly, in a much lesser extent, to adenine have been found.