Time-Dependent Binding Mode of a Cationic Porphyrin Dimer to Poly[d(G-C)2] and Poly[d(A-T)2]
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- 作者：Jae Hong Ko ; Biao Jin ; Minju Lee ; Chang Hwan Bae ; Rita Song ; Maeng Joon Jung ; Seog K. Kim
- 刊名：Journal of Physical Chemistry B
- 出版年：2008
- 出版时间：February 7, 2008
- 年：2008
- 卷：112
- 期：5
- 页码：1502 - 1507
- 全文大小：153K
- 年卷期：v.112,no.5(February 7, 2008)
- ISSN：1520-5207
文摘
The time-dependent binding mode of a porphyrin dimer to poly[d(G-C)2] and poly[d(A-T)2] was investigatedby spectroscopic methods including absorption and circular and linear dichroism (CD and LD) spectroscopy.Immediately after mixing with poly[d(G-C)2], the porphyrin dimer exhibited red-shift and hypochromism inthe absorption spectrum and negative CD and LD spectra. With further red-shift in absorption, the CD andLD magnitude in the Soret region became increasingly negative over time. After it was stabilized, the magnitudeof the reduced LD (LDr) in the Soret region was larger than that in the DNA absorption region, indicatingthat the second porphyrin was also intercalated. Following the rapid intercalation of the first porphyrin, thevery slow intercalation of the second followed with first-order kinetics. In the poly[d(A-T)2] case, a bisignateCD spectrum was observed in the Soret region suggesting stacking of the porphyrins. The small alteration inthe CD spectrum and increased absorbance, which followed the initial rapid spectral change, was of thesecond order. This alteration in the spectral properties was attributed to the conformational change of poly[d(A-T)2] near the binding site because the overall shape of the CD spectrum was conserved in spite of thechanges in the absorption spectrum.