Porphyrin self-assembly as template for RNA?

The self-assembly of chiral porphyrin molecules HpD (hematoporphyrin IX derivative) has been shown to form helical fibers in low salt aqueous conditions. The spectroscopic (UV and circular dichroism (CD)), thermodynamic (Tm, differential scanning calorimetry (DSC)) and microscopic (light and scanning force microscopy (SFM)) examinations of the HpD properties were performed individually and in the presence of nucleic acid double strands (15–60 °C, 0–50 mM NaCl). The asymmetric HpD molecules themselves at room temperature show sharp positive or negative CD signals, which increase enormously with HpD concentration. The data show strong evidence for the external self-stacking interaction of HpD, pure and in the presence of polynucleotides. At low salt concentration (<40 mM NaCl, pH 7) the spectra change completely by increasing the temperature. At 35 to 40 °C RNA-similar spectra of the pure HpD self-assemblies (without nucleic acids) occur. At higher temperatures the aggregates become unstable and break off. ...