Abstract

A discussion of microcalorimetric methods for the detection and analysis of biomolecules. Isothermal Titration Calorimetry (ITC) and Differential Scanning Calorimetry (DSC) offer universal detection systems for biomolecular interaction, and for the analysis of conformational changes within macromolecules, respectively. Detection is based upon ultrasensitive and precise measurement of heat absorbed or released. MicroCal's VP-ITC can determine binding constants, enthalpy, entropy, heat capacity, and the number of binding sites of unmodified reactants in homogenous solution, and has found increasing application in the functional analysis of protein, lipid, and nucleic acid interaction and modeling of binding to cell membranes. ITC is also used in antibody quality control and characterization, and modeling of ligand interaction with cell surface receptors. Ultrasensitive differential scanning calorimeters (DSC) can measure melting temperatures (Tm's) and enthalpic changes associated with protein unfolding transitions and is of particular interest for conformational analysis of multi-domain proteins and for liquid formulation stability studies for proteins and other biomolecules. The newest technologic advancement, Pressure Perturbation Calorimetry (PPC), measures the thermal expansion coefficient of macromolecules in order to assess volumetric properties of biopolymers in solution.