Upon performing 1 H-NMR titration, the chemical shift of specific protons bound to X (eg. receptor) changes during complexation due to non-covalent interactions with another component. Depending on the kinetics of the complex formation, fast and slow exchange can be observed. SupraFit, as most of the other applications, can only handle fast exchange, where the observed signal is the weighted average of all signals of the specific proton in the components, e.g. the shift of a proton assigned to the isolated receptor and one to the complex.