Figure 3.

Detection of EcoR1 methyltransferase activity using PRP release assay. Immobilized linker DNA is incubated with varying concentrations of EcoR1 methyltransferase, followed by PRP binding, and then digested with EcoR1 (solid bars) or Xba1 (open bars). Increasing concentrations of EcoR1 methyltransferase inhibit enzyme-mediated PRP release. Agarose gel electrophoresis shows that in a solution phase assay EcoR1 cleaves the DNA fragment in the absence of methyltransferase, however, the methyltransferase inhibits EcoR1 digestion of the fragment (EcoR1+) and has no effect on Xba1 cleavage (Xba1+) (inset).