Thermodynamics of 2-Cys peroxiredoxin assembly determined by isothermal titration calorimetry

Oligomerization is a frequently encountered physical characteristic of biological molecules that occurs for a wide number of transcription factors, ion channels, oxygen-carrying macromolecules such as hemocyanin and enzymes. On the other hand, unwanted protein oligomerization can lead to the formation of pathogenic structures related with Alzheimer and other diseases. Self-assembly is also a well-described phenomenon within peroxiredoxins, a family of thiol peroxidases. Peroxiredoxin hyperaggregate formation is the key mechanism that triggers the switch between Prx activity as peroxidase and chaperone. The oligomerization process is fundamental for understanding the multiple peroxiredoxin function. The chapter gives a detailed description of typical 2-Cys Peroxiredoxin oligomerization using isothermal titration calorimetry (ITC) and provides a recipe for studying the thermodynamic parameters of peroxiredoxin assembly, that is, association and dissociation constant, enthalpy, entropy, and the Gibbs free energy of the process.