Fig. 2.
Subunit assembly for DNA cleavage by BfiI. (A) Cartoon representations of possible reaction schemes for double-strand DNA cleavage by BfiI. (B) Reactions at 25°C, in reaction buffer at pH 9.0, contained various concentrations of BfiI dimer (25–100 pM) and 3 nM 30/30 duplex, radiolabeled in either bottom or top strand. Samples were taken from the reactions at timed intervals and analyzed as in Experimental Procedures to determine the extent of cleavage of each strand. The steady-state rates for bottom-strand (○) and top-strand (•) cleavages were determined by linear regression; kcat for the bottom strand = 0.20 ± 0.02 min–1.