Electrophoresis of DNA. II. Specific interactions of univalent and divalent cations with DNA

✍ Scribed by Philip D. Ross; Robert L. Scruggs

• Publisher: Wiley (John Wiley & Sons)
• Year: 1964
• Tongue: English
• Weight: 621 KB
• Volume: 2
• Category: Article
• ISSN: 0006-3525
• DOI: 10.1002/bip.1964.360020111

✦ Synopsis

The effect of small quantities of metal ions on the electrophoretic mobility of calf thymus DNA in solutions maintained a t 0.2 ionic strength with weakly interacting (CHa)4N + ions yields information about interactions occurring in a region very close to the polymer chain. By means of this technique, it is demonstrated that the binding order to DNAis Li+> Na+> K+for thealkaIimetaIionsandMn++> Mg++> Ca++ for the divalent ions studied. The quantitative details are compared to earlier work on the long-chain polyphosphates. Close agreement between the two systems is obtained indicating that an intrinsic property of individual phosphate groups is being observed and that minor discrepancies probably arise from secondary factors. Three types of stability constants representing the binding of alkali metal ions to DNA are calculated and although differing in absolute magnitude, they all satisfactorily represent the result that the order of interaction is Li+ > Na+ > K + with respective relative strengths of 1.5: 1 : 0.8.