Figure 3.

Titration of Trp analog labeled RibU W97Y proteins with RBF. The RBF fluorescence was measured at the indicated RBF concentrations in the absence (triangles) or presence (dots) of the W97Y RibU variant (see insets). The difference between these two signals were calculated to build the titration curve. This curve was used to compute the RBF K_d (see Experimental Section in the Supporting Information). Panels from left to right present the results for RibU W97Y, labeled with 5MeW, 5FW, 5,7diFW, and 5,6,7triFW, respectively.