Automated PEAQ MicroCal ITC

In the body many jobs are carried out by proteins coming together in teams for specific purposes like repairing damage to DNA or controlling how cells divide. Understanding how these teams are assembled at the molecular level is fundamental to understanding how our cells work and what goes wrong in disease. One way we can do this is to probe how strongly proteins bind to each other or to other biomolecules such as DNA. We can ask if these interactions are changed when we use proteins with mutations. A very simple way of measuring the extent of interaction between two proteins is to measure the heat given off or consumed when they come together. This is called calorimetry. As the change in heat is very small, in range of thousandths of a calorie, we use a specialised instrument called a microscale-calorimeter. It can tell us not only how strongly the proteins bind but also whether they join together in pairs or other combinations.

An isothermal titration calorimetry (ITC) instrument measures the interaction between two biological samples: one contained within a sample cell in the body of the instrument into which the other sample is injected from a syringe in a succession of small volumes. By very accurately measuring the heat produced when one component in the sample cell comes into contact with another component injected in small aliquots from a syringe, the instrument enables calculation of the total entalphy (DeltaH), the association constant (the inverse of the dissociation constant Kd) and the stoichiometery from the midpoint of the titration. From these parameters the Gibbs free energy (DeltaG) and total entropy change (DeltaS) associated with the interaction can be derived. As interactions in biological systems involve either making or breaking non-covalent bonds where there are associated heat changes, ITC is a technique that can be applied to investigate the interactions of involving all types of biomolecules. Because it requires no labelling, it can measure interactions for unperturbed samples. The proposed Automated PEAQ MicroCal ITC is a low volume calorimeter, that can be programmed to run multiple samples in the absence of user input