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Diastereochemically controlled porphyrin dimer formation on a DNA duplex scaffold
Masayuki Endo1, Mamoru Fujitsuka, Tetsuro Majima
1The Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan. endo@sanken.osaka-u.ac.jp
The Journal of Organic Chemistry
|January 11, 2008
Summary
DNA-porphyrin conjugates form controlled dimer structures within DNA minor grooves. Factors like temperature, linker chemistry, and zinc coordination influence their conformation and stability.
Area of Science:
- Supramolecular Chemistry
- Biophysical Chemistry
- Organic Synthesis
Background:
- DNA-porphyrin conjugates offer a scaffold for constructing ordered molecular architectures.
- Controlling the spatial arrangement of porphyrin units is crucial for tuning their photophysical properties.
Purpose of the Study:
- To synthesize and characterize conformationally controlled porphyrin dimer structures on a DNA template.
- To investigate the influence of factors like zinc coordination and diastereochemistry on porphyrin dimer conformation and DNA binding.
Main Methods:
- Synthesis of DNA-porphyrin conjugates with free-base porphyrin (FbP) and zinc-coordinated porphyrin (ZnP).
- Characterization using Circular Dichroism (CD), UV-vis, steady-state, and time-resolved fluorescence spectroscopies.
- Thermal stability studies (melting temperature) and spectral analysis of duplex formation.
Main Results:
- Porphyrin dimers adopt face-to-face conformations within the DNA minor groove.
- Zinc coordination destabilized both porphyrin dimer and DNA duplex formation.
- Two diastereomers exhibited distinct thermal stabilities and influenced dimer conformation.
- Temperature-dependent assembly and conformational changes of porphyrin dimers were observed.
Conclusions:
- DNA-porphyrin conjugates enable the creation of clockwise overlapped porphyrin dimers in the B-form DNA minor groove.
- Porphyrin dimer conformation and interaction are modulated by temperature, phosphoramidate diastereochemistry, and zinc ion coordination.
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