Figure 7.

Activity of RNase I D241L and D241E mutants. RNase I cleavage of synthetic dsRNA or ssRNA using dilution series of RNase I mutant enzymes. (A) Structure (wt) and homology models (D241L/E) of the Ca²⁺ coordinating site on RNase I. Either a dsRNA substrate (B, F) or a ssRNA substrate (D) was cleaved by the indicated amount of RNase I_D241L (B, D) or RNase I_D241E (F) in the absence or presence of Ca²⁺. The concentration for each enzyme is indicated at the top of each lane. (C, E, G) show the respective quantifications of the uncleaved RNA substrates in (B, D, F). NE, no enzyme control.