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Isothermal Calorimetry (ITC) instrument

The ITC machine measures affinity, stoichiometry, enthalpy change and standard entropy changes for a molecular interaction in a single experiment. The low sample volume means the systems will work with as little as 10µg of protein, which is an important consideration given some users will have limited amounts of material.

ITC measures binding parameters in solution and therefore avoids problems associated with target immobilisation encountered using SPR. The samples used in experiments do not need to be labelled and there are no constraints on the size of proteins/ligands used in the experiments, therefore the machine has utility not only for biologists looking at protein:protein/ligand interactions but is useful for other disciplines e.g. chemistry where the interaction between two small molecules may wish to be investigated.

ITC is particularly suited to people looking at molecular interactions between purified components.

Nanotemper Microscale Thermophoresis (MST) instrument

The MST machine will also measure affinity and stoichiometry, and uses incredibly low volumes/amounts of sample (<4ul as low as 1nM concentration). A major distinction between thermophoresis and ITC is that this machine can measure binding constants with one of the ligands present in a complex mixture such as a cell lysate.

The caveat which further distinguishes it from the ITC is that one of the molecules has to be fluorescently labelled. This might be with a fluorescent dye or GFP for example. Thus this machine will not be suitable for all applications since the addition of a fluorescent tag may alter the biomolecular interaction in certain instances and in these cases ITC will be the more appropriate technology.

The huge advantage of the thermophoresis machine is the ability to quantitate biomolecular interactions in the context of a complex cell lysate using minuscule amounts of sample. This means interactions can be analysed between large macromolecular assemblies such as the ribosome or spliceosome and individual ligands.

Contact the Biosciences research team for more information.