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Differential scanning fluorimetry follows fluorescence while a protein sample undergoes controlled heating. Changes associated with protein unfolding provide a transition curve and an apparent protein unfolding midpoint. Comparing matched conditions turns the method into a thermal shift assay.^[ref]

In a common implementation, an environment-sensitive fluorescent dye reports changes as normally buried regions become exposed. Compare otherwise matched protein-plus-dye samples with and without a candidate ligand, rather than comparing measurements made with different buffers or heating programs. Fluorescent compound-only and dye-only controls can help diagnose reporter interference; these are proposed controls, not specific settings claimed for every published assay.

For an illustrative result, midpoints of $320\mathrm{K}$ and $324\mathrm{K}$ give a thermal shift of $+4\mathrm{K}$. The measured quantity is a change in a heating-dependent transition. An independent ligand binding or activity measurement is needed to assess the proposed molecular mechanism, as illustrated by the comparisons with isothermal titration calorimetry in the 2004 evaluation.^[ref]

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]

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]

For an invented example, suppose a consistently defined midpoint changes from $48{}^{\circ }\mathrm{C}$ in the control to $52{}^{\circ }\mathrm{C}$ 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]

Protein denaturation, protein aggregation and cleavage of peptide bonds are different events. A fluorescence trace alone must not be assumed to identify all three.