Cationic porphyrins bearing diazolium rings: Synthesis and their interaction with calf thymus DNA

Daryono H. Tjahjono, Takehiro Akutsu, Naoki Yoshioka, Hidenari Inoue

Research output: Contribution to journalArticle

81 Citations (Scopus)


Two novel cationic porphyrins bearing five-membered rings at the meso- positions, meso-tetrakis(1,3-dimethylimidazolium-2-yl)porphyrin (H2TDMImP) and meso-tetrakis(1,2-dimethylpyrazolium-4-yl)porphyrin (H2TDMPzP), have been synthesized. These two compounds interact with calf thymus DNA (CTDNA) in different binding modes from that of meso-tetrakis(N-methylpyridinium-4- yl)porphyrin (H2TMPyP). H2TDMImP outside binds to the minor groove of CTDNA while H2TDMPzP intercalates into CTDNA. These two novel cationic porphyrins strongly bind to CTDNA even at high ionic strength and the binding constant of H2TDMPzP to CTDNA is comparable to that of H2TMPyP. The binding of H2TDMImP to CTDNA is enthalpically driven. The favorable free energy changes in binding of H2TDMPzP to CTDNA come from the large negative enthalpy changes accompanied by small positive entropy changes.

Original languageEnglish
Pages (from-to)333-343
Number of pages11
JournalBiochimica et Biophysica Acta - General Subjects
Issue number1-2
Publication statusPublished - 1999 Oct 18



  • Binding constant
  • Cationic porphyrin
  • Imidazole
  • Porphyrin-DNA complex
  • Pyrazole
  • Thermodynamic parameter

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology

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