Hydrogen bonding, overlap geometry, and sequence specificity in anthracycline antitumor antibiotic.DNA complexes in solution.

Abstract
Structural aspects of the intercalation complex of the anthracycline antitumor antibiotic daunomycin and its analogs with the synthetic DNA poly(dA-T) were deduced by 1H and 31P NMR in high-salt solution. The base pairs are intact at the antibiotic binding site; the anthracycline phenolic hydroxyls form intramolecular H bonds with the quinone carbonyls and are shielded from solvent in the intercalation complex. The complexation shifts of the exchangeable phenolic and nonexchangeable aromatic protons demonstrate that rings B and C of the anthracycline chromophore overlap with adjacent base pairs; anthracycline ring D passes right through the intercalation site in the complex. Two resolved 31P resonances attributable to the dA-dT and dT-dA phosphodiester linkages in the P spectra of the neighbor-exclusion daunomycin.cntdot.poly(dA-dT) complex were observed. The anthracycline antitumor antibiotic apparently exhibits a sequence specificity in its intercalation complex with alternating purine-pyrimidine synthetic DNA in solution. These conclusions on H bonding and overlap geometry at the intercalation site and sequence specificity for the daunomycin.cntdot.poly(dA-dT) complex in solution are in agreement with the structure of the daunomycin.cntdot.dC-dG-dT-dA-dC-dG hexanucleotide duplex crystalline complex at atomic resolution published recently.

This publication has 22 references indexed in Scilit: