Kinetic Methods of Deducing Binding Mechanisms Involving Intrinsically Disordered Proteins

There are multiple examples of protein-protein interactions involving one intrinsically disordered protein region binding to an ordered protein domain in a coupled binding and folding reaction. Similarly to protein folding studies, much effort has been devoted to understanding the mechanisms of such coupled binding and folding reactions. In this chapter, we describe how kinetics can be used to assess binding mechanisms with focus on fluorescence-monitored stopped-flow experiments. The approach can be applied more generally to any protein interaction with or without a coupled conformational change and to other kinetic techniques. Determining binding mechanisms is a great challenge and while "proving" a mechanism may be futile, it is possible to deduce the simplest scenarios, which are consistent with experimental data.