Duplex structure formation between oligo(dA)'s and oligo(dT)'s generated by thymine-specific interaction with netropsin

Abstract

The formation of oligomeric duplex molecules in the presence of the antibiotic netropsin in the series p(dA)_n·p(dT)_n is demonstrated using low–temperature CD measurements. Addition of Netropsin to mixtures of oligomers generates the same type of CD spectra as observed for poly(dA)·poly(dT) and maintains the duplex structure at temperatures at which base pairing of free oligomers is thermodynamically unstable. The shortest chain length forming a netropsin complex by thymine-specific interaction with the oligopeptide is represented by p(dA)₄·p(dT)₄ Studies with sequence isomers show that adjacent thymine residues strongly favour the complex formation with the oligopeptide.