Overview of Biophysical Assay Services

Biophysical assays enable understanding of the drug-target interaction on a molecular level. The residence time, mechanism of action, and kinetics are crucial for the therapeutic action of a drug and essential for the selection of analytes with the most promising properties for the next stage of drug discovery. Our team of biophysical assay experts, together with an array of cutting edge instrumentation, is available for hit identification, hit-to-lead, and lead characterization activities tailored to the needs of your research project.

Reaction Biology offers off-the-shelf biophysical assays, custom assay development, and optimization as well as integrated projects in close interaction with our team of biophysical assay experts.

Overview of the four biophysical assays offered at Reaction Biology.

	Surface Plasmon Resonance (SPR)	Isothermal Titration Calorimetry (ITC)	Microscale Thermophoresis (MST)	Thermal Shift Assay (TSA)
Physical Principle	Optical measurement that detects molecular mass changes of the target upon analyte binding	Measures the heat released or absorbed during analyte binding to a target	Measures the changes in the motion of target molecules along microscopic temperature gradients upon analyte binding	Monitors the shift in melting temperature of a target upon analyte binding
Binding Affinity Determination				X
Parameters Measured	Dissociation constant (KD) Association rate constant (kon) Dissociation rate constant (koff)	Dissociation constant (KD) Binding enthalpy (ΔH) Binding stoichiometry	Dissociation constant (KD)	Shift in melting temperature (ΔTm)
Capacity	Medium to high throughput	Low throughput	Medium throughput	High throughput
Sample Requirements	Purified target and agents required	Purified target and agents required	Purified target and agents required in most cases	Purified target and agents required
Dynamic Ranges	pM to mM	pM to mM	pM to mM	N/A
Advantages	Provides kinetic parameters (on/off rates) and is measured in real-time	Provides thermodynamic parameters and binding stoichiometry	Wide range of targets including small molecules and large macromolecular complexes	Fast and inexpensive
Immobilization	Target immobilized to the sensor chip	In solution	In solution	In solution
Labeling	Label-free	Label-free	Fluorescent labeling of the target required	Label-free

Surface Plasmon Resonance (SPR)

SPR is a highly sensitive technique for accurate measurement of the interactions of two biomolecules with respect to binding kinetics and affinity as well as binding specificity.

Isothermal Titration Calorimetry (ITC)

ITC is a solution based assay that measures the heat released or absorbed as the result of a chemical reaction.

Microscale Thermophoresis (MST)

MST assays measure the motion of molecules along microscopic temperature gradients that changes upon ligand binding.

Thermal Shift Assay (TSA)

Thermal shift assays measure the thermal stability of a target protein and the increase in protein melting temperature upon the binding of a stabilizing agent. It is useful for identifying ligands, buffer conditions and cofactors affecting protein stability.