The line 1 representsthe untreated plasmid (native DNA) with its two forms: the upperone is DNA with single strand break and the faster migrating band issupercoiled (closed circular) plasmid. Native DNA contains a highconcentration of supercoiled DNA and low concentration of DNAwith single strand break. Incubation of plasmid DNA with Fenton’sreagent in the absence of FPHs resulted in the complete degradationof the two DNA bands