Binding of Carminomycin to synthetic polyribonucleotides poly(A) and poly(U): absorption and polarized fluorescence study

TL;DR

This study investigates how the antibiotic carminomycin binds to synthetic polyribonucleotides poly(A) and poly(U) using absorption and fluorescence spectroscopy, revealing two distinct binding modes depending on dye concentration.

Contribution

It identifies and characterizes two different binding modes of carminomycin to polyribonucleotides, providing thermodynamic insights into each interaction.

Findings

Two binding modes identified: surface self-assembly at low P/D ratios and monomeric binding at high P/D ratios.

Thermodynamic parameters for both binding modes were estimated.

Binding behavior varies with phosphate-to-dye ratio, affecting the mode of interaction.

Abstract

Binding of anthracycline antibiotic carminomycin (CM) to synthetic polyribonucleotides poly(A) and poly(U) was studied in solution of low ionic strength in a wide phosphate-to-dye (P/D) range using absorption and polarized fluorescence spectroscopy. Two different modes of CM binding to the ss-polynucleotides have been identified. The first of them dominating at low phosphate-to-dye (P/D) ratios is self-assembly of the heterocyclic dye on the polymer surface driven by to cooperative electrostatic binding of amino group of CM sugar moiety to negatively charged polynucleotide phosphate groups with the chromophores self-stacking. At high P/D values, the stacking-associates disintegrate and monomeric binding of ligand to nucleic bases become prevalent. Thermodynamic parameters of binding were estimated for the both cases.