[DNA-tropic inhibitors of nuclease action on DNA in liver nuclei].
Distamycin is a potent, wide-spectrum inhibitor of the breaking of both free and intranuclear DNA with DNAse I and with own nuclear nucleases. It compares very favourably with actinomycin D, proflavin and ethidium bromide, especially in the inhibition of DNAse I action in the nuclei. This seems likely to be due to partial overlapping of the binding sites of the nuclei with chromatin proteins in contrast to distamycin that interacts with a minor furrow of DNA being blocked to a less extent by proteins. The DNA-tropic agents under test exert no qualitative effect on the kinetics of intranuclear DNA splitting by DNAse I. Carminomycin and bleomycin are the least effective inhibitors in all the systems depicted.