AGGREGATION OF DNA ENHANCED BY THE PROTOBERBERINE ALKALOIDS, CORALYNEAND BERBERINE

The aggregation of DNA caused by coralyne was studied by spectroscopic , viscosity and electric birefringence measurements. Aggregation was m arkedly enhanced over a narrow range of coralyne to DNA phosphate rati o and then followed by precipitation. The electric birefringence measu rements indicated that the ratio at the maximal aggregation varied dep ending on the concentration of coralyne, finally reaching 1:1 at highe r concentrations. The particles (type I) for such enhanced aggregation were estimated to be prolate ellipsoids 1700-4000 Angstrom in length with a diameter of 1400-4000 Angstrom. At higher coralyne concentratio ns, another particle (type II) was formed which was a thick rod-like p article 1700-4000 Angstrom in length with a diameter of 120-210 Angstr om. These dimensions indicate that type I and II particles consist res pectively of several tens of thousands and some hundreds of molecules of DNA. On the other hand, berberine did not produce such a marked agg regation of DNA, and the result was a thick rod-like particle 1700-400 0 Angstrom in length with a diameter of 300-1000 Angstrom. The enhance ment by coralyne and berberine is discussed in terms of intermolecular interactions.