Biophysics

Surface Plasmon Resonance is a label-free technology for measuring biomolecular interactions. Analytes (e.g. small molecules, peptides, nucleic acids, or proteins) are injected over a surface of captured target (e.g. protein of interest). Association and dissociation data are collected, allowing for the time-resolved quantification of interactions and calculation of kinetic k_a and k_d constants. May also be used to confirm binding and determine thermodynamic parameters and stoichiometry. Functional range: 1 pM to 500 µM. (Tags: Binding Assays, Kinetic Assays, Thermodynamic Assays, Stoichiometry Assays)

Bio-Layer Interferometry is a label-free technology for measuring biomolecular interactions. A protein or peptide of interest is immobilized onto an optical biosensor tip and the tip is then dipped into an analyte solution. Association and dissociation data are collected, allowing for the time-resolved quantification of interactions and calculation of kinetic k_a and k_d constants. (Tags: Binding Assays, Kinetics Assays)

Isothermal Titration Calorimetry is a physical technique used to determine the thermodynamic parameters (K_D, ΔH, ΔS, ΔG, stoichiometry) of binding partners in solution. Functional range: 1 nM to 100 µM.  (Tags: Binding Assays, Thermodynamic Assays, Stoichiometry Assays)

Fluorescence Polarization is a homogeneous, steady-state, solution-based assay involving a single fluorescently labeled binding partner that is used for the determination of the thermodynamic dissociation constant (K_D). The technique is highly amenable to plate-based high-throughput screening and hit discovery campaigns. Functional range: 1 nM to 1 mM. (Tags: Binding Assays, Thermodynamic Assays, Stoichiometry Assays)

Time-Resolved Fluorescence Energy Transfer is a highly sensitive and robust drug discovery assay/technique involving fluorescently labelled donor and acceptor proteins that is used to determine both thermodynamic and kinetic parameters (K_D, EC₅₀, k_a, k_d). Functional range: 1 pM to 1 mM. (Tags: Binding Assays, Kinetic Assays, Thermodynamic Assays, Functional Assays)

Nuclear Magnetic Resonance. Various 1D and 2D NMR experiments are available, including ¹H and ¹⁹F binding assays (e.g. STD-NMR), in addition to ¹H-¹³C and ¹H-¹⁵N correlation spectroscopy. Compound titrations allow for K_D determination. Sensitivity: µM range. (Tags: Binding Assays, Stoichiometry Assays)

Circular Dichroism is a biophysical technique involving circularly polarized light. It is used to investigate the secondary structure of proteins and protein homogeneity. (Tags: Stability/Release Assays)

Dynamic Light Scattering is a biophysical technique that is used to determine the size distribution profile (i.e. homogeneity) of proteins in solution. Information obtained: translational diffusion coefficient (D_t), R_h, d_h, B₂₂, k_D, viscosity. Functional range: ~0.1 nm to 10 µm. (Tags: Stability/Release Assays)

Mass Spectrometry encompasses a wide array of available instrumentation and techniques for determining the mass of proteins and peptides in solution. May be used to confirm protein identity and sequence. HDX (Hydrogen/Deuterium Exchange) spectroscopy is also available and is used to monitor and inform on structural aspects (e.g. ordered vs. disordered regions) and dynamic behavior of proteins in solution.  (Tags: Binding Assays, Stoichiometry Assays, Stability/Release Assays)