DNA-binding geometry dependent energy transfer from 4′,6-diamidino-2-phenylindole to cationic porphyrins

Biao Jin, Kil Sik Min, Sung Wook Han, Seog K. Kim

Research output: Contribution to journalArticlepeer-review

18 Scopus citations


The circular and linear dichroism (CD and LD) spectral properties of the meso-tetrakis(N-methylpyridinium-4-yl)porphyrin (TMPyP)-DNA complex at a [porphyrin]/[DNA] ratio below 0.015 showed that TMPyP intercalates between DNA base pairs. Contrarily, when cis-bis(N-methylpyridinium-4-yl)porphyrin (BMPyP) is associated with DNA, no CD spectrum was induced and a bisignate LD spectrum was observed. These spectral properties of both the TMPyP and BMPyP were essentially retained when the minor groove of the DNA was saturated with 4′,6-diamidino-2-phenylindole (DAPI). The fluorescence of the DNA-bound DAPI was effectively quenched by BMPyP and TMPyP. The quenching by BMPyP can be described through a pure static mechanism while TMPyP quenching produced an upward bending curve in the Stern-Volmer plot. Quenching efficiency was by far greater than predicted by the "sphere of action model", suggesting that the DNA provides some additional processes for an effective energy transfer.

Original languageEnglish
Pages (from-to)38-45
Number of pages8
JournalBiophysical Chemistry
Issue number1-2
StatePublished - Sep 2009


  • 4′,6-Diamidino-2-phenylindole
  • DNA
  • Energy transfer
  • Luminescence
  • Porphyrin


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