Figure 6.

Single turnover on AACAA. The reaction in SfiI assay buffer at 30°C contained 10 nM AACAA (5′-end-labelled with ³²P in the top strand) and 20 nM SfiI endonuclease. At timed intervals after adding SfiI, samples were withdrawn from the reactions and analysed as in the Materials and Methods to determine the percent cleavage. The data were fitted to a single exponential and the optimal fit (indicated by the line) was obtained with a value of 1.2 min^–1.