{ "id": "epb7vmggbg", "slug": "differential-scanning-fluorimetry", "title": "Differential scanning fluorimetry", "updated": "2026-10-25", "topic_path": [ { "id": "life", "label": "Life and health", "api_url": "https://www.edgepedia.org/api/v1/topics/life" }, { "id": "life.biology", "label": "Biological foundations", "api_url": "https://www.edgepedia.org/api/v1/topics/life.biology" }, { "id": "life.biology.biochemistry", "label": "Biochemistry and metabolism", "api_url": "https://www.edgepedia.org/api/v1/topics/life.biology.biochemistry" }, { "id": "life.biology.biochemistry.practice", "label": "Biochemistry field and methods", "api_url": "https://www.edgepedia.org/api/v1/topics/life.biology.biochemistry.practice" }, { "id": "life.biology.biochemistry.practice.methods", "label": "Biochemical methods and techniques", "api_url": "https://www.edgepedia.org/api/v1/topics/life.biology.biochemistry.practice.methods" }, { "id": "life.biology.biochemistry.practice.methods.assays", "label": "Assay techniques", "api_url": "https://www.edgepedia.org/api/v1/topics/life.biology.biochemistry.practice.methods.assays" } ], "geo": [ { "id": "geo.nongeo.t1946.life.biology.biochemistry.practice.methods.assays", "label": "Non-geographic · 1946 to 2000: Assay techniques", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo.t1946.life.biology.biochemistry.practice.methods.assays", "path": [ { "id": "geo.nongeo", "label": "Non-geographic", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo" }, { "id": "geo.nongeo.t1946", "label": "Non-geographic · 1946 to 2000", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo.t1946" }, { "id": "geo.nongeo.t1946.life", "label": "Life and health", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo.t1946.life" }, { "id": "geo.nongeo.t1946.life.biology", "label": "Biological foundations", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo.t1946.life.biology" }, { "id": "geo.nongeo.t1946.life.biology.biochemistry", "label": "Biochemistry and metabolism", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo.t1946.life.biology.biochemistry" }, { "id": "geo.nongeo.t1946.life.biology.biochemistry.practice", "label": "Biochemistry field and methods", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo.t1946.life.biology.biochemistry.practice" }, { "id": "geo.nongeo.t1946.life.biology.biochemistry.practice.methods", "label": "Biochemical methods and techniques", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo.t1946.life.biology.biochemistry.practice.methods" }, { "id": "geo.nongeo.t1946.life.biology.biochemistry.practice.methods.assays", "label": "Assay techniques", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo.t1946.life.biology.biochemistry.practice.methods.assays" } ] } ], "excerpt": "Differential scanning fluorimetry (DSF), also called the thermal shift assay or ThermoFluor, heats a protein while monitoring fluorescence to measure its melting temperature and ligand binding.", "snippet": "Differential scanning fluorimetry (DSF), also called the thermal shift assay or ThermoFluor, heats a protein while monitoring fluorescence to measure its melting temperature and ligand binding.", "node": "life.biology.biochemistry.practice.methods.assays", "markdown": "# Differential scanning fluorimetry\n\nDifferential scanning fluorimetry (DSF) is an in vitro method that heats a purified protein while monitoring fluorescence to determine its melting temperature (\\( T_{\\mathrm{m}} \\)) and the shift in \\( T_{\\mathrm{m}} \\) caused by ligand binding. It is also called the thermal shift assay (TSA) or ThermoFluor, and it is a workhorse of protein characterization and early-stage drug discovery because it needs little protein, no specialized instrumentation, and delivers results within a day.[1](https://www.nature.com/articles/nprot.2007.321) • [2](https://doi.org/10.1016/j.xpro.2023.102688)\n\n| Key fact | Value |\n|---|---|\n| Standard conditions | 5 µM protein, 5× SYPRO Orange (10 µM), 25–95 °C at 1 °C/min[2](https://doi.org/10.1016/j.xpro.2023.102688) |\n| Output per run | Melting curve, \\( T_{\\mathrm{m}} \\) (Boltzmann or first-derivative fit), \\( \\Delta T_{\\mathrm{m}} \\) versus control[2](https://doi.org/10.1016/j.xpro.2023.102688) |\n| \\( \\Delta T_{\\mathrm{m}} \\) at ligand \\( K_{\\mathrm{D}} \\) | Typically 1–12 °C; below 1 °C for fragments, above 12 °C for covalent ligands[2](https://doi.org/10.1016/j.xpro.2023.102688) |\n| Throughput | ~30 min per 96-well plate, 1–5 µg protein per well; 384-well formats available[3](https://cmi.hms.harvard.edu/sites/g/files/omnuum4016/files/2025-03/CMI%20QuantStudio%20DSF%20Getting%20Started%20Guide.pdf) |\n| Failure rate | 15–25% of recombinant proteins give non-ideal denaturation curves[4](https://pmc.ncbi.nlm.nih.gov/articles/PMC4332540/) |\n| Label-free variant | nanoDSF monitors intrinsic tryptophan and tyrosine fluorescence at 330/350 nm and works in detergent-containing solutions[5](https://link.springer.com/content/pdf/10.1007/s12551-020-00619-2.pdf) |\n\n## How it works\n\nA protein is heated at a controlled rate while a fluorescent reporter tracks unfolding. In the most common format, the dye SYPRO Orange binds hydrophobic regions exposed as the protein unfolds, producing a large increase in quantum yield; the fluorescence trace versus temperature is a melting curve whose midpoint defines \\( T_{\\mathrm{m}} \\), the temperature at which 50% of the sample is folded and 50% unfolded.[1](https://www.nature.com/articles/nprot.2007.321) • [4](https://pmc.ncbi.nlm.nih.gov/articles/PMC4332540/) • [5](https://link.springer.com/content/pdf/10.1007/s12551-020-00619-2.pdf) SYPRO Orange's excitation and emission maxima fall within the filter sets of standard real-time PCR instruments, and the assay is inexpensive to run.[6](https://www.ncbi.nlm.nih.gov/books/NBK586874/) • [4](https://pmc.ncbi.nlm.nih.gov/articles/PMC4332540/) • [1](https://www.nature.com/articles/nprot.2007.321)\n\nA ligand that stabilizes the folded state raises \\( T_{\\mathrm{m}} \\); the difference \\( \\Delta T_{\\mathrm{m}} \\) between ligand and control is related to binding affinity.[1](https://www.nature.com/articles/nprot.2007.321) Tm is extracted either by fitting the truncated curve to a Boltzmann sigmoid or from the peak of the first derivative of fluorescence.[2](https://doi.org/10.1016/j.xpro.2023.102688) • [4](https://pmc.ncbi.nlm.nih.gov/articles/PMC4332540/) An alternative readout is the protein's intrinsic tryptophan fluorescence, which shifts between 330 nm and 350 nm on unfolding; because dye binding to the unfolded form shifts the folding equilibrium, apparent \\( T_{\\mathrm{m}} \\) values from dye-based and intrinsic measurements can differ.[7](https://link.springer.com/article/10.1007/s12551-025-01280-3)\n\n## How it is done\n\nA typical run mixes 5 µM protein with 5× SYPRO Orange (10 µM) in a buffer such as 20 mM HEPES pH 7.4, 100 mM NaCl, in a 96-well PCR plate, and ramps 25 °C to 95 °C at 1 °C/min on a real-time PCR instrument; \\( \\Delta T_{\\mathrm{m}} \\) is the tested condition's \\( T_{\\mathrm{m}} \\) minus the control \\( T_{\\mathrm{m}} \\).[2](https://doi.org/10.1016/j.xpro.2023.102688) Optimization ranges of 0.5–10× dye and 2–20 µM protein usually suffice, and the assay miniaturizes readily to 384- or 1536-well plates.[4](https://pmc.ncbi.nlm.nih.gov/articles/PMC4332540/) A QuantStudio-style run collects data in about 30 minutes per 96-well plate, consuming 1–5 µg per well in 20 µL volumes.[3](https://cmi.hms.harvard.edu/sites/g/files/omnuum4016/files/2025-03/CMI%20QuantStudio%20DSF%20Getting%20Started%20Guide.pdf) Thermo Fisher recommends at least four replicates per reaction, and ligand-only controls to reveal ligand–dye interactions.[8](https://genomics2.lsu.edu/documentation/vendor/qPCR_Protein_Thermal_Shift_Studies%28software-vB.0%29.pdf) Raising the heating rate from 1 to 4 °C/min has little effect on ligand detection but quadruples throughput, although \\( T_{\\mathrm{m}} \\) values generally increase with heating rate.[9](https://liebertpub.com/doi/10.1089/adt.2011.0390)\n\n## Origin\n\nFluorescence-monitored thermal denaturation of proteins has been used since at least the 1960s, and the continuous 1 °C/min ramp protocol was established in the 1970s and 1980s on the assumption of pseudo-equilibrium.[7](https://link.springer.com/article/10.1007/s12551-025-01280-3) • [2](https://doi.org/10.1016/j.xpro.2023.102688) The high-density miniaturized thermal shift assay for drug discovery was reported by Michael W. Pantoliano and colleagues in 2001 in SLAS DISCOVERY;[10](https://doi.org/10.1177/108705710100600609) some reviews date the underlying system to 1997, while the published high-throughput record is the 2001 paper, and the two accounts have not been reconciled.[5](https://link.springer.com/content/pdf/10.1007/s12551-020-00619-2.pdf) • [6](https://www.ncbi.nlm.nih.gov/books/NBK586874/) Daumantas Matulis and colleagues showed in 2005 that ThermoFluor yields binding affinities and stoichiometries for carbonic anhydrase in [Biochemistry](https://www.edgepedia.org/biochemistry),[11](https://doi.org/10.1021/bi048135v) Ulrika B. Ericsson and colleagues adapted the method to high-throughput protein stability optimization for structural studies in 2006 in Analytical Biochemistry,[12](https://doi.org/10.1016/j.ab.2006.07.027) and Frank H. Niesen, Helena Berglund, and Masoud Vedadi published the protocol under the name differential scanning fluorimetry in 2007 in Nature Protocols.[1](https://www.nature.com/articles/nprot.2007.321) The SYPRO Orange and SYPRO Red dyes themselves were described by Thomas H. Steinberg and colleagues in 1996 in Analytical Biochemistry as gel stains.[13](https://doi.org/10.1006/abio.1996.0319)\n\n## Variants\n\nLabel-free and membrane-protein formats remove the extrinsic dye. nanoDSF monitors intrinsic tryptophan and tyrosine fluorescence at 330 nm and 350 nm, typically as the \\( F_{350}/F_{330} \\) ratio, in capillary formats such as the 48-capillary Prometheus NT.48 heated at 1 °C/min; unlike dye-based DSF, it tolerates detergent-containing solutions, a prerequisite for membrane proteins, whose lipid bilayers and micelles bind hydrophobic dyes.[5](https://link.springer.com/content/pdf/10.1007/s12551-020-00619-2.pdf) • [14](https://onlinelibrary.wiley.com/doi/10.1002/pro.3622) nanoDSF needs about 50-fold less sample and 20-fold less time than conventional fluorimetry, using 15 µL volumes and a minimum reliable protein concentration of 15 µg/mL.[14](https://onlinelibrary.wiley.com/doi/10.1002/pro.3622) The CPM assay instead uses the thiol-specific fluorochrome N-[4-(7-diethylamino-4-methyl-3-coumarinyl)phenyl] maleimide, which reacts with cysteines exposed during unfolding, and supplies most current examples of DSF on integral membrane proteins.[9](https://liebertpub.com/doi/10.1089/adt.2011.0390) • [2](https://doi.org/10.1016/j.xpro.2023.102688) GFP-tag DSF follows the tag's fluorescence loss on denaturation but is unsuitable for targets with a \\( T_{\\mathrm{m}} \\) near GFP's, since GFP only starts losing fluorescence around 75 °C.[5](https://link.springer.com/content/pdf/10.1007/s12551-020-00619-2.pdf)\n\nPlate-based and dye-library formats extend the method. Microplate intrinsic DSF excites at 280 nm and collects emission from 310–420 nm in 384-well plates at 10 µL per sample,[15](https://pmc.ncbi.nlm.nih.gov/articles/PMC11881137/) and modulated scanning fluorimetry (MSF) runs on the same hardware to report a nonreversibility onset temperature that marks the onset of aggregation.[15](https://pmc.ncbi.nlm.nih.gov/articles/PMC11881137/) Protein-adaptive DSF (paDSF) pairs proteins with dyes from a 312-dye Aurora library spanning 470/520 nm to 660/705 nm, succeeding on 94% of 70 tested proteins (including 10 [SARS-CoV-2](https://www.edgepedia.org/sars-cov-2) proteins) compared with roughly 29% for SYPRO Orange.[16](https://www.nature.com/articles/s41587-024-02158-7) Analysis software has matured alongside these formats: DSFworld, published in Protein Science in 2024, introduced models accommodating multiple transitions, high initial signal, and temperature-dependent signal decay, validated against a database of 6,235 raw curves.[17](https://doi.org/10.1002/pro.5022)\n\n## Applications\n\nIn drug discovery, DSF serves as a primary screen: ThermoFluor screening of MurF against 200,000 compounds produced 17 hits, one inhibiting MurF with an \\( \\mathrm{IC}_{50} \\) of 25 µM, and HDM2 was screened against roughly 400,000 compounds with a hit rate below 0.4%.[9](https://liebertpub.com/doi/10.1089/adt.2011.0390) Beyond screening, published uses include buffer optimization for storage, assay, and crystallization; refolding buffer screens; measurements in unpurified chemical reactions; and biotherapeutic formulation, where nanoDSF monitored BSA stability through nanoparticle formulation steps in 10 µL samples.[5](https://link.springer.com/content/pdf/10.1007/s12551-020-00619-2.pdf) • [18](https://www.mdpi.com/1999-4923/15/5/1473) Binding parameters can be estimated from the dependence of \\( T_{\\mathrm{m}} \\) on ligand concentration, but \\( \\Delta T_{\\mathrm{m}} \\) validation typically correlates only for similarly structured compounds within a series.[5](https://link.springer.com/content/pdf/10.1007/s12551-020-00619-2.pdf)\n\n## Limitations and alternatives\n\n**Protein requirements.** The protein must unfold cooperatively within roughly 15–85 °C on qPCR instruments; proteins with \\( T_{\\mathrm{m}} \\) above 98 °C show no distinct melt phase, and intrinsically disordered proteins or small proteins lacking hydrophobic regions, such as ubiquitin, fail to generate usable curves.[2](https://doi.org/10.1016/j.xpro.2023.102688) • [8](https://genomics2.lsu.edu/documentation/vendor/qPCR_Protein_Thermal_Shift_Studies%28software-vB.0%29.pdf) • [6](https://www.ncbi.nlm.nih.gov/books/NBK586874/)\n\n**Artifacts.** SYPRO Orange fluoresces aberrantly with glycerol, detergents, lipids, and EDTA, is quenched at pH below 5 or above 10, and gives high background with micelles and membranes; dye-related artifacts are the most common cause of failed or misinterpreted results.[2](https://doi.org/10.1016/j.xpro.2023.102688) BSA must never be in the assay buffer because it binds the dye strongly,[3](https://cmi.hms.harvard.edu/sites/g/files/omnuum4016/files/2025-03/CMI%20QuantStudio%20DSF%20Getting%20Started%20Guide.pdf) and as little as 0.1 mg/mL polysorbate almost completely masks the SYPRO Orange unfolding transition, although intrinsic DSF tolerates it.[15](https://pmc.ncbi.nlm.nih.gov/articles/PMC11881137/) Compounds can induce protein-independent dye fluorescence, reduced dramatically by 0.001% [Triton X-100](https://www.edgepedia.org/triton-x-100);[2](https://doi.org/10.1016/j.xpro.2023.102688) replacing SYPRO Orange with the paDSF dye T004 cut such false positives in one screen from 8% to 2% of compounds.[16](https://www.nature.com/articles/s41587-024-02158-7) Negative thermal shifts are commonly observed and can be explained by equilibrium models, and a negative shift does not exclude binding to the native state.[19](https://onlinelibrary.wiley.com/doi/10.1002/9783527683604.ch07) • [5](https://link.springer.com/content/pdf/10.1007/s12551-020-00619-2.pdf)\n\n**ΔTm versus affinity.** No general correlation exists between \\( \\Delta T_{\\mathrm{m}} \\) and binding affinity, because the shift reflects affinity at the melting temperature, which can differ substantially from affinity at 25 °C; DSF gives false negatives for enthalpy-driven binding and false positives for entropy-driven binding, so positive hits should be confirmed with a quantitative orthogonal method such as microscale thermophoresis or ITC.[7](https://link.springer.com/article/10.1007/s12551-025-01280-3)\n\n**Alternatives.** DSC directly measures heat absorbed during unfolding without dyes and provides \\( T_{\\mathrm{m}} \\), \\( \\Delta H \\), and heat capacity, and with CD it remains the gold standard when DSF dyes fail, but it is low-throughput; DSF offers far higher throughput and smaller volumes but no enthalpy or heat-capacity data.[20](https://www.malvernpanalytical.com/en/learn/knowledge-center/insights/dsf-vs-dsc-in-biopharmaceutical-research) • [2](https://doi.org/10.1016/j.xpro.2023.102688) CETSA is a distinct technique performed in cells or lysates rather than on purified protein.[2](https://doi.org/10.1016/j.xpro.2023.102688) nanoDSF free energies and unfolding temperatures are comparable to DSC values, with higher throughput and lower sample consumption, provided the protein contains tryptophan or tyrosine.[21](https://cmi.hms.harvard.edu/differential-scanning-fluorimetry)\n\n## References\n\n1. [The use of differential scanning fluorimetry to detect ligand interactions that promote protein stability (Niesen, Berglund & Vedadi, Nat Protoc 2007)](https://www.nature.com/articles/nprot.2007.321)\n2. [Protocol for performing and optimizing differential scanning fluorimetry experiments (STAR Protocols, 2023)](https://doi.org/10.1016/j.xpro.2023.102688)\n3. [Harvard HMS CMI QuantStudio DSF Getting Started Guide](https://cmi.hms.harvard.edu/sites/g/files/omnuum4016/files/2025-03/CMI%20QuantStudio%20DSF%20Getting%20Started%20Guide.pdf)\n4. [Thermal Shift Assay (Current Protocols in Protein Science)](https://pmc.ncbi.nlm.nih.gov/articles/PMC4332540/)\n5. [Theory and applications of differential scanning fluorimetry in early-stage drug discovery (Gao, Oerlemans & Groves; Biophysical Reviews 2020; excerpts merged from PMC copy PMC7040159)](https://link.springer.com/content/pdf/10.1007/s12551-020-00619-2.pdf)\n6. [Chapter 15: Thermofluor-Based Analysis of Protein Integrity and Ligand Interactions (Methods in Molecular Biology)](https://www.ncbi.nlm.nih.gov/books/NBK586874/)\n7. [Differential scanning fluorimetry followed by microscale thermophoresis and/or isothermal titration calorimetry as an efficient tool for ligand screening (Biophysical Reviews, 2025)](https://link.springer.com/article/10.1007/s12551-025-01280-3)\n8. [qPCR Protein Thermal Shift Studies(software vB.0) (genomics2.lsu.edu)](https://genomics2.lsu.edu/documentation/vendor/qPCR_Protein_Thermal_Shift_Studies%28software-vB.0%29.pdf)\n9. [Thermal Denaturation Assays in Chemical Biology (Assay and Drug Development Technologies)](https://liebertpub.com/doi/10.1089/adt.2011.0390)\n10. [Michael W. Pantoliano and colleagues (2001). High-Density Miniaturized Thermal Shift Assays as a General Strategy for Drug Discovery. SLAS DISCOVERY.](https://doi.org/10.1177/108705710100600609)\n11. [Daumantas Matulis and colleagues (2005). Thermodynamic Stability of Carbonic Anhydrase: Measurements of Binding Affinity and Stoichiometry Using ThermoFluor. Biochemistry.](https://doi.org/10.1021/bi048135v)\n12. [Ulrika B. Ericsson and colleagues (2006). Thermofluor-based high-throughput stability optimization of proteins for structural studies. Analytical Biochemistry.](https://doi.org/10.1016/j.ab.2006.07.027)\n13. [Thomas H. Steinberg and colleagues (1996). SYPRO Orange and SYPRO Red Protein Gel Stains: One-Step Fluorescent Staining of Denaturing Gels for Detection of Nanogram Levels of Protein. Analytical Biochemistry.](https://doi.org/10.1006/abio.1996.0319)\n14. [Facile measurement of protein stability and folding kinetics using a nano differential scanning fluorimeter (Protein Science, 2018)](https://onlinelibrary.wiley.com/doi/10.1002/pro.3622)\n15. [Intrinsic Differential Scanning Fluorimetry for Protein Stability Assessment in Microwell Plates (2025)](https://pmc.ncbi.nlm.nih.gov/articles/PMC11881137/)\n16. [Protein-adaptive differential scanning fluorimetry using conformationally responsive dyes (Nature Biotechnology, 2024; excerpts merged from PMC preprint copy PMC9900766)](https://www.nature.com/articles/s41587-024-02158-7)\n17. [Taiasean Wu, Zachary J. Gale‐Day, Jason E. Gestwicki (2024). DSFworld : A flexible and precise tool to analyze differential scanning fluorimetry data. Protein Science.](https://doi.org/10.1002/pro.5022)\n18. [Nano Differential Scanning Fluorimetry as a Rapid Stability Assessment Tool in the Nanoformulation of Proteins (Pharmaceutics, 2023)](https://www.mdpi.com/1999-4923/15/5/1473)\n19. [Fragment-Based Drug Discovery Lessons and Outlook (DSF chapter, Wiley)](https://onlinelibrary.wiley.com/doi/10.1002/9783527683604.ch07)\n20. [How to choose between DSF vs DSC in biopharmaceutical research (Malvern Panalytical, March 2025)](https://www.malvernpanalytical.com/en/learn/knowledge-center/insights/dsf-vs-dsc-in-biopharmaceutical-research)\n21. [Differential Scanning Fluorimetry (DSF), Harvard Medical School Center for Macromolecular Interactions](https://cmi.hms.harvard.edu/differential-scanning-fluorimetry)\n\n---\n*Topic: Encyclopedia › Life and health › Biological foundations › Biochemistry and metabolism › Biochemistry field and methods › Biochemical methods and techniques › Assay techniques*\n\n*Initially written Sep 29, 2026 · Edited: Oct 15, 2026; Oct 25, 2026*\n\n*Copyright 2026 EdgeChat AI, a subsidiary of Biostate AI.*\n\nLicense: Edgepedia Community License 1.0, https://www.edgepedia.org/edgepedia/license\n", "same_as": [], "url": "https://www.edgepedia.org/differential-scanning-fluorimetry", "markdown_url": "https://www.edgepedia.org/differential-scanning-fluorimetry.md", "license": { "name": "Edgepedia Community License 1.0", "url": "https://www.edgepedia.org/edgepedia/license", "summary": "Free with credit, commercial use included. AI training is open to everyone. 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Edgepedia Community License 1.0.", "speakable": "Differential scanning fluorimetry, also called the thermal shift assay or ThermoFluor, heats a protein while monitoring fluorescence to measure its melting temperature and ligand binding." }