Binding curve direction for Temperature-Related Intensity Change (TRIC)
For binding affinity analysis, ligand-dependent changes in Temperatrue-Related Intensity Change (TRIC) are plotted as Fnorm values vs. ligand concentration. The 'direction' of the binding curve is has no influence on further Kd analysis. For example, the TRIC response of a given target is typically a reduction in fluorescence in the detection volume upon induction of a temperature gradient, represented by a descending TRIC trace. The TRIC response of the complex, however, can be either stronger than that of pure target (reducing the fluorescence even further, Figure 1A), or it can be weaker (causing a smaller reduction in fluorescence, Figure 1B). The 'direction' of the curve therefore depends on the specific properties of the molecules and does not influence further analysis.
Figure 1. TRIC binding curve direction.