Intrinsic differential scanning fluorimetry (intrinsic DSF) is most commonly associated with proteins containing tryptophan residues, whose strong fluorescence signal provides excellent sensitivity for monitoring thermal unfolding. However, because tryptophan is the least abundant amino acid found in proteins, a substantial fraction of naturally occurring and engineered proteins contain few or no tryptophan residues, making sensitive detection of tyrosine fluorescence essential for broad applicability of the technique.
This technical note demonstrates the ability of SUPR-DSF™ to characterize challenging proteins that contain tyrosine as the sole intrinsic fluorescent amino acid. Using four commercially available proteins spanning a wide range of molecular weights, tyrosine contents, and thermal stabilities, we evaluate both the practical sensitivity limits of the technique and the influence of protein concentration on measured thermal stability. The results demonstrate that full-spectrum fluorescence acquisition combined with BCM analysis enables robust thermal unfolding measurements at protein concentrations as low as 0.1 mg/mL, even for proteins containing only a single tyrosine residue.
