Figure 3.

Direct comparison between tmFRET distances and the x-ray crystal structure distances. a) Plot of FRET efficiences compaired to the calculated Cα-Cα distances in the crystal structure between F5M-labeled MBP mutants and nickel. The same measurements between F5M and copper (b), mBBr and nickel (c), and mBBr and copper (d). Plot of distances calculatd from FRET comapired to disntanes calulcated from the x-ray crystal structure for between F5M and nickel (e), F5M and copper (f), mBBr and nickel (g), and mBBr and copper (h). For comparisons, the probe pairs defined as fixed are shown as open circles and the dynamic pairs are shown as solid circles. i) Comparison between the APO state distances and the HOLO state distances for fixed pairs in F5M-labeled MBP donors with nickel (green) or copper (blue) acceptors. j) The same comparison for fixed pairs in mBBr-labeled MBP. k) comparison between the APO state distances and the HOLO state distances for dynamic pairs in F5M-labeled MBP donors with nickel (green) or copper (blue) acceptors. l) The same comparison for dynamic pairs in mBBr-labeled MBP. m) Measured distance changes for dynamic pairs labeled with F5M compaired to distance chages measured from the crystal structures. n) Calculated distance changes for dynamic pairs labeled with mBBr compaired to changes from the crystal structures.