BINDING OF A DESMETALLO-PORPHYRIN CONJUGATE OF HOECHST 33258 TO DNA. III. STRONG BINDING TO SINGLE-STRAND OLIGONUCLEOTIDES

Abstract

The binding of the conjugate of Hoechst 33258 with 5,10,15,20-tetrakis (1-methyl-4-pyridyl)-21H,23H-porphyrin (PORHOE) to single-strand DNA has been detected by UV–vis spectrophotometry and ¹H-NMR. The red-shift of porphyrin Soret band with strong hypochromicity indicates that the porphyrin moiety dominates in the interaction of the PORHOE with ssDNA. The affinity constants of PORHOE for d(GCATACAATTCG) or d(CGAATTGTATGC) were determined to be >10⁵ M ⁻¹, with strong cooperativity.

Keywords:

• Single strand DNA
• Ligand
• NMR
• Binding constant

ACKNOWLEDGMENTS

We are grateful to the EU for the provision of a Marie-Curie Postdoctoral Fellowship (SF) and to the BBSRC for support (EVB), to Dr. Martin Baron for access to the 400 MHz instrument.