ABSTRACT
There are two implementations of calorimetry, isothermal titration calorimetry (ITC) and differential scanning calorimetry (DSC). In ITC, heat is used as a direct probe to follow bindingreactions and to obtain binding curves. An isothermal titration calorimeter consists of two cells, one for the sample and one for the reference buffer. The primary readout for heat in modern ITC and DSC instruments is electric power. A typical ITC experiment of 1 h duration can be shortened to about 20 min by the single injection method. Towards the end of the ITC experiment, when 100% complex has been formed, additional injections should lead to no or only very small heat changes. Unfolding of a protein during the ITC experiment adds the ΔH of unfolding to the measured heat and severely distorts the signal. ITC can also be used to measure the steady-state enzyme kinetic parameters kcat and KM for enzymatic.
