Figure 4.

Dissociation kinetics of GDP from its complex with FtsY NG fragment. The complex between the NG fragment and GDP was generated by premixing 33.6 μM GDP with 2.2 μM NG fragment in one syringe of a stopped-flow apparatus and mixing with 500 μM mantGDP in the other syringe in the actual experiment. Excitation was at 295 nm, and fluorescence was detected above 389 nm. The continuous line shows a double-exponential fit to the data with rate constants of 3.74 ± 0.10 and 0.21 ± 0.02 s⁻¹.