Fig 4.
Restriction enzyme sensitivity of Marvin DNA. Marvin DNA was digested with the enzymes DpnI, Dpn II, HpaII, MspI, and McRBC as indicated, and the products were separated by agarose gel electrophoresis. Lane 2 contains undigested genomic DNA; Lane M is a 1-kbp size marker. Note that DpnI and Dpn II are isoschizomers (recognizing 5′-GATC), and DpnI only cuts DNA if the recognition site is methlylated, whereas DpnII is blocked by dam methylation. Likewise, HpaII and MspI are isochizomers (recognizing 5′-CCGG), and HpaII is blocked by CpG methylation, whereas MspI is insensitive to site methylation. McrBC (lane 7) that recognizes 5′-PumC(N40–3000)PumC only cuts methylated DNA.