[Nucleotide specificity of sibiromycin interaction with DNA].

Sibiromycin binds selectively to poly(dG).poly (dC) and poly(dG--dC).poly (dG--dC) and does not interact with poly(dA--dT).poly(dA--DT), poly (dI).poly (dC) and poly(dI--dC).poly(dI-dC) as is evident from the changes in the UV spectrum of the antibiotic at 310 mn, differential CD spectrum and inhibition of the template activity of polynucleotides in the DNA-dependant RNA-polymerase system. Sibiromycin efficiently interacts with GC-rich DNA specifically methylated at N-7 of guanine and glucosilated DNA of T2 phage. Therefore, specific interaction of sibiromycin with the guanine sites may take place rather in the narrow groove than in the large groove of the double helix.