USE AND ACTIVITY OF METALS IN BIOLOGICAL-SYSTEMS - I - THE INTERACTION OF BIVALENT-METAL CATIONS WITH DOUBLE-STRANDED POLYNUCLEOTIDES AND PHOSPHOLIPIDS

Triple complexes of DNA (or model double stranded polyadenilic-polyuri dilic acid) and unilamellar vesicles of egg phosphatidylcholine with n ine bivalent cations have been studied. Turbidimetric measurements hav e been used as experimental tool, on the basis of the widely accepted, assumption, that complexation is responsible for-aggregation. EPR mea surements and metal and phosphorus analysis on a complex with Mn2+ all owed a definite stoicheiometry to be determined and a possible structu re for the complexes to be proposed, where each bivalent cation acts a s a bridge among two phosphate groups of DNA and three molecules of ph osphatidylcholine. The presence of the cations is able to modify the I R-FT spectra of the double complexes vesicles-DNA significantly.