Figure 4 - Effects of delta’-E mutants. (a) Clamp binding and release from FRET experiments compared to clamp loaders containing wild-type delta’-E subunits. Clamp binding (red bars) and clamp release (green bars for 6.6 µM DNA, blue bars for 5 mM ADP plus DNA) was calculated by changes in donor fluorescence by the same methods as Figure 2b. (See Supplementary Fig. 2 for raw data.) Error bars represent the standard error of at least two measurements. (b) DNA-binding affinity for delta’-E mutants. 100 nM tamra-labeled DNA was excited at 550 nm with emission signal collected at 580 nm in the presence of 1 uM wild-type beta, 1 mM ADP-BeFx. Fits obtained using the equation as described in Materials & Methods. (c) Dissociation constants of delta’-E mutants for DNA. Error bars shown are the standard error of the fit. All clamp loaders examined contained wild-type gamma-BCD subunits unless noted otherwise.