RELATION BETWEEN STRONG BINDING OF SPERMINE TO POLYNUCLEOTIDES AND CONFORMATION OF POLYNUCLEOTIDES

The formation of stable complexes between [14C]spermine and synthetic polynucleotides was analyzed by gel filtration on a Sephadex column; a striking feature was noted in regard to complex formation and the conformation of polynucleotides. Among the polynucleotides examined (poly A, poly U, poly C, poly I and mixtures of these polynucleotides), spermine formed stable complexes with those having the conformation of antiparallel double helix, for instance, with the double-stranded (poly A+poly U) complex. However, the spermine-polynucleotide complex was not observed when the polynucleotide had a nonrigid conformation or even a stable acidic parallel double-helical conformation. When the temperature was elevated, the association of spermine and double-stranded (poly A+poly U) was destroyed in accordance with the helix-coil transition of the strands observed by abrupt increase of ultraviolet absorption. In addition, spermine also formed stable complexes with tRNA, rRNA from Escherichia coli and MS2 bacteriophage RNA. © 1969.