THE ELECTROPHORETIC SEPARATION OF CURVED CISPLATIN-MODIFIED DNA FRAGMENTS ON POLYACRYLAMIDE GELS IS DEPENDENT ON THE VOLTAGE GRADIENT

Polyacrylamide gel electrophoresis has been widely used to study DNA f ragments containing sequence-dependent curvature. The anomalous electr ophoretic behavior of curved DNA fragments on such gels allows their s eparation from straight fragments of the same length. Here we demonstr ate that polyacrylamide gels can be successfully used to resolve DNA f ragments modified at a single site by the antitumor drug cis-diammined ichloroplatinum(II) (cis-DDP, cisplatin) from their unmodified counter parts. However, the resolution strongly depends on the voltage gradien t, being completely lost when it drops below a certain threshold level . The parameters of the electric field do not affect separation of 'no rmal' DNA fragments of comparable length.