Raman spectroscopy of an O(2)-Co(II)bleomycin-calf thymus DNA adduct: alternate polymer conformations. |
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| Authors: | C Rajani J R Kincaid D H Petering |
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| Institution: | Department of Chemistry, University of Wisconsin-Milwaukee, P.O. Box 413, Milwaukee, WI 53211, USA. |
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| Abstract: | Bleomycin (Blm) is an antitumor agent which binds to specific sequences of DNA and as HO(2)-Fe(III)Blm causes single and double strand cleavage. In the present investigation, binding of O(2)-Co(II)Blm to a native DNA polymer, calf thymus DNA, was examined using conventional Raman spectroscopy. O(2)-Co(II)Blm is a model for O(2)-Fe(II)Blm, the direct precursor of HO(2)-Fe(III)Blm. Although the DNA polymer retained a predominant B-form structure, Raman spectral evidence was obtained for localized structural changes to A, C and Z-DNA forms. The presence of these alternate DNA forms within B-DNA implied the presence of B/A, B/C and B/Z junctions. The observed changes in DNA secondary structure were attributed to perturbation of structural water resulting from binding of O(2)-Co(II)Blm within the minor groove. |
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