Deglyco-peplomycin metal complexes on DNA fibers: a role of the sugar moiety for the stability and the orientation of the complexes |
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Authors: | Takamasa Iiyama Makoto Chikira Takanori Oyoshi Hiroshi Sugiyama |
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Institution: | 1-13-27, Kasuga, Bunkyo-ku, Tokyo 112-8551, Japan, 2-3-10 Kanda-Surugadai, Chiyoda-ku, Tokyo 101-0062, Japan,
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Abstract: | Binding structures of metal complexes of deglyco-peplomycin (dPEP) on DNA were investigated by comparing dPEP complexes with those of bleomycin (BLM) using DNA fiber EPR spectroscopy. A low spin species of Fe(III)dPEP observed in the DNA pellet changed irreversibly to several high spin species after the fabrication of the DNA fibers. The g values of the high spin species were different from those of Fe(III)BLM. The high spin species could not be nitrosylated reductively to ON-Fe(II)dPEP, suggesting that some nitrogen atoms coordinated to the Fe(III) were displaced on the DNA fibers. On the other hand, O(2)-Co(II)dPEP remained intact on the fibers similarly to O(2)-Co(II)BLM but with an increased randomness in the orientation on the DNA. In contrast to Cu(II)BLM, a considerable amount of Cu(II)dPEP bound almost randomly on B-form DNA fibers. These results indicated that the sugar moiety in peplomycin or bleomycin is playing an important role in enhancing the stability of the metal-binding domain and in the stereospecificity of the binding on DNA. |
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