Figure 4.

Double-strand cleavage of target DNA by R1Bm EN. The 175-bp substrates described in Fig. 3a were incubated without (lanes 1) or with 2 μg of R1Bm EN enzyme (lanes 2). The arrows indicate the size of the double-stranded DNA products resulting from cleavage on both strands at the R1Bm insertion site. The expected cleavage products would be 67 and 94 bp long with 3′ overhangs of 14 nt, the effect of which on electrophoretic mobility is uncertain. Molecular weight standards (M_r) are radiolabeled pBR322 DNA MspI fragments.