Wuhan YanGeneBio Wuhan YanGeneBio is an innovative biotechnology service company dedicated to drug target discovery and drug mechanism validation. We provide solutions spanning from target discovery to mechanism validation for novel drug development, the modernization of traditional Chinese medicine, and natural product research. By integrating core technologies—including drug target fishing approaches such as ABPP, TPP, and Lip-MS; drug–target interaction site identification via crosslinking mass spectrometry and Lip-MS combined with molecular docking; affinity detection platforms (SPR/MST/BLI/ITC/DSF) for drug–target binding; high-throughput screening platforms such as protein microarrays and Olink multiplex assays; as well as siRNA drug synthesis and organoid-based drug screening—we deliver high-precision services in compound target identification, binding site analysis, affinity validation, and functional verification for our clients. Molecular interactions are the core foundation of life activities. The precise quantification of binding affinity and kinetic parameters between biomolecules represents a critical technical demand in drug development, target discovery, and mechanism elucidation. MicroScale Thermophoresis (MST) technology, with its core advantages of in-solution in situ detection, high sensitivity, and low sample consumption, overcomes the limitations of traditional interaction analysis techniques and has become a mainstream tool for molecular interaction research. This article systematically describes the principles of MST, the standardized experimental workflow, and data analysis methods; demonstrates its core advantages with comparative data; and showcases its technical value through representative application cases, providing a reliable technical reference for research and translation in the biomedical field. Principles of MST MST is based on the thermophoretic properties of molecules within a microscopic temperature gradient field, enabling precise quantitative analysis of molecular interactions. An infrared laser creates a local temperature gradient (ΔT ≈ 1–5 °C) in the detection system; fluorescently labeled target molecules undergo directed thermophoresis within the gradient, and their migration rate is jointly determined by molecular size, surface charge, hydration shell thickness, and conformational state. When the target molecule specifically binds a ligand, the physicochemical properties of the molecule change, producing a detectable shift in the thermophoretic migration rate. This process is recorded via fluorescent signal changes; combined with concentration-gradient titration and non-linear fitting, the dissociation constant (Kd), binding kinetic parameters (kon/koff), and stoichiometry are precisely calculated, achieving molecular interaction resolution from qualitative to quantitative. The technology does not require immobilizing molecules on a solid-phase support and performs detection in a solution system close to the physiological environment, maximally preserving the native conformation and binding activity of molecules. It is particularly suitable for interaction analysis of complex systems such as membrane proteins, difficult-to-purify proteins, small-molecule compounds, and nucleic acids. Its detection range covers affinities from the pM to mM level, meeting the full-spectrum needs from weak to strong interactions. Standardized Experimental Workflow of MST (I) Sample Preparation and Labeling Target molecule preparation: For target molecules such as purified proteins, cell lysates, and nucleic acids, labeling is performed using fluorescent dyes (e.g., Cy5, NHS fluorescent dyes) or His-tag-specific labeling kits, with labeling efficiency controlled at 50%–90% to avoid impairing molecular activity due to over-labeling; Ligand gradient dilution: Dilute the ligand (small molecule, protein, peptide, etc.) in 2-fold or 3-fold gradient steps, set 12–16 concentration points covering a 100-fold range around the expected Kd value, to ensure a complete binding curve; System optimization: Screen buffer components (pH, salt concentration, detergent) to eliminate non-specific binding and ensure detection system stability. (II) Incubation and Loading Mix the labeled target molecule with the gradient-diluted ligand at equal volumes, incubate at room temperature for 10–30 min to allow the binding reaction to reach equilibrium; draw the incubated sample into a standard capillary, avoiding bubbles to ensure homogeneity of the detection region. (III) Detection and Data Acquisition Place the capillary into the MST instrument, set parameters such as laser power, detection temperature, and acquisition time, and start detection; the instrument records in real time the fluorescence intensity changes before and after temperature gradient formation, obtaining raw thermophoretic curves. Three replicates are set for each concentration point to reduce experimental error. (IV) Data Analysis Process the raw data using specialized analysis software: first remove outliers (e.g., curve shifts caused by aggregation or non-specific binding), plot the normalized fluorescent signal (Fnorm) against ligand concentration to obtain a dose–response binding curve; perform non-linear fitting using a 1:1 binding model, multiple-site binding model, etc., to calculate the Kd value, binding kinetic parameters, and Hill coefficient, and evaluate binding specificity and cooperative effects. Summary of Core Advantages Low consumption and high efficiency: sample consumption is only 1/5–1/10 of traditional techniques, and experimental duration is shortened by over 60%, greatly improving detection efficiency; Strong compatibility: no sample purification required; direct detection in complex biological matrices (cell lysates, serum, liposomes) breaks through the sample preparation bottleneck; Conformational fidelity: in-solution in situ detection avoids molecular conformational changes caused by solid-phase immobilization, ensuring the biological authenticity of binding data; High sensitivity: capable of detecting weak interactions between small molecules (<100 Da) and proteins, as well as ions and biological macromolecules, filling the gap left by traditional techniques. Representative Application Cases (I) Drug Target Discovery and Validation In the screening of targets for active ingredients of traditional Chinese medicine, MST was used to directly detect the interaction between paeoniflorin and the MEK2 protein in cell lysate, without a protein purification step. Experimental results showed that the Kd value of wild-type MEK2 for paeoniflorin was 2.8 ± 0.5 μM, whereas the binding affinity of mutant MEK2 (kinase domain mutation) for paeoniflorin was significantly reduced (Kd > 100 μM). This clarified that paeoniflorin exerts its effect by targeting the MEK2 kinase domain, providing direct molecular evidence for the modernization of traditional Chinese medicine. (II) Small-Molecule Drug Affinity Screening For anti-tumor drug candidate molecules, MST was used to screen binding activity against the E2F2 transcription factor. In the experiment, only a trace amount of His-tagged E2F2 cell lysate was needed, without purification, to complete the binding detection of gradient-diluted bufalin, with a measured Kd value of 3.15 ± 1.43 μM. Specific binding between the drug and the target was simultaneously verified, ruling out false-positive results and providing precise quantitative data for drug optimization. (III) Membrane Protein Interaction Research Membrane proteins are strongly hydrophobic and difficult to purify, making interaction analysis difficult with traditional techniques. Using MST, the binding between a G protein-coupled receptor (GPCR) and its ligand was directly detected in a detergent-containing buffer, with a measured Kd value of 12.5 ± 2.1 nM, in high agreement with cellular-level functional assays. This proves that MST can break through the technical barriers of membrane protein research and provides a reliable platform for GPCR-targeted drug development. (IV) Nucleic Acid–Protein Interaction Quantification In transcription regulation mechanism research, MST was used to detect the binding of a transcription factor to a DNA promoter sequence, with a measured Kd value of 89.3 ± 11.2 nM. The effects of different mutation sites on binding affinity were simultaneously analyzed, clarifying the key binding sequence and providing a quantitative basis for elucidating gene expression regulatory mechanisms. MST Service Advantages and Experimental Scope (I) Service Advantages Fully standardized workflow: from sample labeling, system optimization to data analysis, a standardized operating procedure (SOP) is established to ensure repeatability and reliability of results, with RSD < 5%; Complex system adaptation: for complex samples such as difficult-to-purify proteins, membrane proteins, and natural extracts, customized experimental schemes are provided, eliminating the need for cumbersome sample pretreatment; Multi-dimensional data analysis: in addition to the Kd value, multi-dimensional parameters including binding kinetics, stoichiometry, and binding cooperativity are provided simultaneously, comprehensively resolving molecular interaction mechanisms; Efficient delivery: routine samples are tested and reported within 7 working days; expedited samples within 3 working days, meeting the time requirements of research and translation. (II) Covered Experiment Types 5. Protein–small molecule interactions: drug screening, target validation, lead compound optimization; 6. Protein–protein interactions: complex assembly, signaling pathway mechanisms, antibody affinity maturation; 7. Nucleic acid–protein interactions: transcription regulation, RNA-binding protein research, gene editing mechanisms; 15. Membrane protein interactions: binding analysis of GPCRs, ion channels, transporters, and ligands; 8. Other interactions: quantification of protein–peptide, protein–polysaccharide, and ion–biomacromolecule interactions. Conclusion and Outlook With its core advantages of in-solution in situ detection, low sample consumption, high sensitivity, and strong compatibility, MST overcomes the limitations of traditional molecular interaction techniques and has become a core tool for molecular interaction research in the biomedical field. From drug target discovery and small-molecule screening to mechanism elucidation, MST provides precise and reliable quantitative data, supporting full-chain innovation from basic research to clinical translation. As the technology continues to be refined, MST will achieve new breakthroughs in single-cell-level interaction analysis, in vivo molecular interaction detection, and high-throughput drug screening, providing stronger technical support for life science research and the development of the biomedical industry.
MST Platform
