Fig. 2.

ATP hydrolyzed by CYT-19 per separation event of the 6-bp P1 duplex with low Mg²⁺ concentration (2 mM). Open and filled circles show results from 2 identical experiments. The solid curve shows the best fit by a model that includes stimulation of unwinding by bound ATP without hydrolysis (see SI Text, Stimulation of Strand Separation by Bound ATP). Dashed curves show best fits to discarded models in which only free CYT-19 gives ATP hydrolysis-independent strand separation (long dashes) or in which ATP-bound CYT-19 can give strand separation without hydrolysis, but with the same efficiency as nucleotide-free CYT-19 (short dashes).