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Spectroscopic study on the interactions of trace elements Co., Mn, Mg and Al with d(GCGTACGC) indicated the following: Al and Mg did not alter Tm values. Mn enhanced Tm at lower concentration and decreased it at higher concentrations. Interestingly Co at higher concentration elevated the Tm. These studies also showed lower concentrations of Mn displaced EtBr, whereas Al could displace it at higher ionic strength. Mg and Co displaced EtBr fluorescence at moderate concentrations. The binding constant values and CD spectra clearly indicated strong binding of these elements to DNA.

Spectroscopic study of the interactions of metal (CD) spectra of the oligomers in a concentration-depenions, Co, Mn, Mg and Al with d(GCCCATGGGC) and dent manner. The CD spectra of d(GCCCATGGGC) and d(CCGGGCCCGG) indicated B and Z forms of DNA, d(CCGGGCCCGG) revealed the following. Metal ions Mn, Al and Mg at the lowest concentrations enhanced respectively, in contrast to the A form observed in the the t m of oligomers, whereas Mn and Mg at higher crystal structures. Mg and Co at different ionic strength concentrations decreased the t m . Co enhanced the t m of induced Z-B transition in d(CCGGGCCCGG), while Al oligomers at higher concentrations. The studies have also at higher concentrations induced a Z-A transition. Mn indicated that Mn at lower concentrations displaced EtBr did not induce any transition. This is the first report to fluorescence, Mg and Co at moderate concentrations and show that Al causes structural transitions in sequenceAl only at higher concentrations. Addition of Co, Mn, specific oligomers and has strong binding ability with Mg and Al altered the bands of the circulars dichroism GC-rich euchromatin oligomers.Metal ions are known to be involved in the stabilization of DNA strands and in the catalytic activity of DNA polymerases [1]. Transition metals such as Mn and Co at higher ionic strength are found to be mutagenic and carcinogenic and also change the handedness of their DNA [1 -6]. Al is reported to be associated with neurological disorders [7] and causes cellular toxicity through its interaction with DNA in cells [8 -9]. Many data are available on the effect of metal ions on the melting behaviour of genomic DNA, uDNA, poly (A-T) and poly (G-C) [10 -12]. However, the precise mechanisms of binding of the metal ions to DNA are not yet clearly understood. Metal-binding studies on defined short sequences of DNA are also limited [13][14][15][16] and would be of interest in this connection. Recently, the crystal structures of the two oligomers d(CCGGGCCCGG) and d(GCCCATGGGC) were solved in our laboratory. Both structures crystallize isomorphously and are found to adopt the A-DNA conformation in the crystals. They exhibit interesting changes in their local conformation which are brought about by base sequence and crystal-packing forces. We report here the melting behaviour and spectroscopic analysis of the metal ion interactions of Mn, Co, Mg and Al with the two deoxyoligonucleotides which were carried out to understand their structure in the solution