| Cancers and its complications have become the adverse problems that seriously threaten human health world widely. However, there is some difficulty in treatment the cancer efficiently. The best existing way of curing cancers is to detect the states of patients frequently and then adjust the quantity of necessary medical dose; thereby the cancers of patients can be controlled and the complications of it can be prevented or relieved. Cancer is caused by many factors in which the chemical masteries such as As, Cd, Ni and Benzene, etc, hold the first place. Metal masteries, for example Hg, Ag, Pb, Cd, As, Cr, Ni, are harmful to DNA, RNA, enzyme, protein and cell membrane and will cause the taking place of cancers and mutations of them. So the normal metabolize and split are damaged, the immunity function, the anti-cancer function will be weakened. It is very difficult to be cured once he or she is toxic. Zn is a necessary element for man and is named as "the light of life". But superfluous Zn also affects the properties of DNA and leads its configuration unstable. The Itai-Itai Disease and the "Shui Yu" disease were caused by metal ions. So to study the interaction of metal ions with DNA is very important in biology and applications for us to understand to toxic mechanism and guard against diseases.In this paper, we used Raman spectroscopic technique to study different metal ions with different concentrations and found that in Cd-DNA solution, when R increases from 0 to 0.5, 1.0, 1.5, 3.0, the corresponding Raman spectra of 835.0cm-1 are 835.0cm-1, 832.0cm-1, 832.0cm-1, 829.0cm-1, 827.0cm-1,respectively. The spectrum of the double helix B-DNA macromolecule at 835.0cm-1 shiftes about 8cm-1. The overlapping spectra of 1446.0cm-1 and 1461.0cm-1 separates with increasing of Cd2+ which is different from ancient experiments and each moves to 1441.0cm-1 and 1458.0cm-1, respectively. But in Zn-DNA solution, the corresponding center postions of 835.0cm-1 with increasing of R are 835.0, 835.0, 832.0, 827.0 and 823.0cm-1, respectively. The bandwidth of 1095.0 and 1491.0cm-1 are broadened acutly. Both thefrequency and intensity of 1146.0cm-1 change largely, etc. Discussed and compared the mechanism of these interaction in detail we got some conclusions as following:Both Zn2+ and Cd2+ions can chelate with PO2- and come into being - PO2-Me2+N7(purine) chelate. As to Zn2+ ions, when R2.0 , the quantity of PO2-Zn2+N7 is directly linear with R. When R2.0, Zn2+ions even can chelate with C at N3-O2 sites and this chelation will disrupt the H-bond between GC base pairs and make the DNA structure unstable. As to Cd2+ ions, only when R is within 1.0-1.5 can this chelation take place and the relation of the quantity of this chelate with R is not easy to conclude.Both Zn2+ and Cd2+ ions can interact with AT and GC bases but the binding degree is different from different ions and even to the same ions it will change with the change of ions concentrations. In low metal ions concentration environment, Zn2+ ions bind to AT are easier than to GC, whereas in higher metal ions concentration surroundings, Zn2+ ions bind to GC are easier than to AT, so in higher Zn2+ ions environment, GC bases are damaged larger than AT. Cd2+ ions mainly bind to AT bases and these interactions will disrupt the H-bond between AT base pairs, destroy the stability of DNA and lead the percent of GC to increase.In a word, both Zn2+ and Cd2+ ions can interact with DNA and make it alter its conformation from a normal B-DNA into a modified B'-DNA.At last, a prospect of Raman spectroscopy in its developments and applications was proposed. The effects of Raman spectroscopy became more and more important with the progresses of laser bean and the putting in practice of ameliorate measures and this technique will expand to other fields.
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