A thermal shift assay compares a protein's temperature-dependent unfolding transition between experimental conditions, often with and without a candidate ligand. The measured shift reports altered thermal behaviour. It is commonly used to investigate ligand binding without first requiring an assay of the protein's biological activity.[ref]
High-density miniaturized thermal shift assays as a general strategy for drug discovery by M. W. Pantoliano and others. 2001, Abstract; energetic coupling and miniaturized screening
In differential scanning fluorimetry, an environment-sensitive fluorescent dye reports changes during heating. A temperature-controlled instrument measures fluorescence from matched control and compound-containing samples. The resulting apparent protein unfolding midpoint is a feature of the measured transition; it need not be a reversible equilibrium melting temperature.[ref]
Evaluation of fluorescence-based thermal shift assays for hit identification in drug discovery by Mei-Chu Lo and others. 2004, Abstract; dye-based unfolding measurement and instrument
For an invented example, suppose a consistently defined midpoint changes from in the control to with a compound. ThenThis indicates thermal stabilization under the tested conditions. It does not by itself give a room-temperature dissociation constant or establish inhibition of enzyme activity. The 2004 study compared the method with isothermal titration calorimetry and activity assays, illustrating the value of an independent readout.[ref]
Evaluation of fluorescence-based thermal shift assays for hit identification in drug discovery by Mei-Chu Lo and others. Abstract; orthogonal affinity and enzymatic-assay comparisons
Protein denaturation, protein aggregation and cleavage of peptide bonds are different events. A fluorescence trace alone must not be assumed to identify all three.
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