INTERACTION OF RNA POLYMERASE INHIBITOR CHROMOMYCIN WITH DNA

Formation of a complex between chromomycin and DNA has been shown to depend on the guanine content and on base pairing of the polydeoxynucleotides. A limit of association is reached when one chromomycin molecule is bound per four nucleotide base pairs. The rate of complex formation is independent of the size of the sugar side chains of the antibiotic and of the nature and base composition of DNA. In contrast the rate of complex dissociation increases with a decrease in size of the sugar side chains. The inhibition by chromomycin and its derivatives of DNA and RNA polymerase reactions exhibits similar features. Probably the dissociation rate of the complex determines the inhibitory activity. Chromomycin by complex formation protects guanine rich segments of DNA very efficiently against the attack of nucleases. After enzymatic hydrolysis chromomycin containing base paired oligonucleotide fragments remain in the reaction mixture and can be isolated by electrophoresis. The antibiotic is not covalently bound to these fragments and can be removed by thorough extraction with ether. Copyright © 1969, Wiley Blackwell. All rights reserved