Figure 5.

Alternative two-step kinetic mechanisms for ATP binding to Rho-MatB. Rho-MatB and Rho-MatB* represent two different fluorescence states of the protein with Rho-MatB* having the higher fluorescence. (A) Conformational selection model. In the absence of ATP, the protein exists in two conformations, but only Rho-MatB₂ can bind ATP. It is assumed that the fluorescence change occurs only on the second step. (B) Induced fit model. Rho-MatB binds ATP, and then the ATP-bound protein goes to the other conformation.