Nucleic Acids Research, 1985, Vol. 13, No. 24 8955-8967
© 1985
Articles |
Interaction of DAPI with double-stranded ribonucleic acids
Dipartimento di Biochimica, Biofisica e Chimica delle Macromolecole, Università di Trieste 34127 Trieste 1Istituto di Chimica Biologica, Università di Catania 95125 Catania, Italy
Received August 7, 1985. Revised November 6, 1985. Accepted November 6, 1985.
The interaction of DAPI with natural and synthetic double-stranded polyribonucleotides was studied with different optical and calorimetric methods. The results were similar to those obtained previously with double-stranded polydeoxynucleotides, i.e. two interaction modes, the first of which shows high affinity for AU clusters and consequent strong fluorescence enhancement. The results suggest caution in the use of DAPI as selective fluorescent staining agent for DNA in the presence of RNA. A narrov groove binding model with hydrogen bonds between DAPI and AU pairs is proposed. An intercalation mechanism can be excluded because of the non planarity of DAPI molecule.