FIG 4.

Representative streptothricin affinity determination experiments. Conditions for the performance of ITC experiments are detailed in Materials and Methods. (A and C) Isotherms of streptothricin binding to BsSatA^WT and BaSatA^WT, respectively. (B and D) Isotherms of streptothricin binding to BsSatA^L128F and BaSatA^Y164F. In all cases the insets show the thermodynamic parameters of the binding events. Each experiment was performed thrice, and the dissociation constants shown in the insets are for a single experiment. They differ slightly from those shown in Table 2, because those shown in Table 2 are averages from the three experimental values. Data for panel A were previously published (26) and are being used as a point of reference.