Protein-Protein Interactions

Volume 1278 of the series Methods in Molecular Biology pp 183-204

Characterization of Protein-Protein Interactions by Isothermal Titration Calorimetry

  • Adrian Velazquez-CampoyAffiliated withInstitute of Biocomputation and Physics of Complex Systems (BIFI), Joint Unit IQFR-CSIC-BIFI, Universidad de ZaragozaDepartment of Biochemistry and Molecular and Cell Biology, Universidad de ZaragozaFundacion ARAID, Government of Aragon
  • , Stephanie A. LeavittAffiliated withGilead Sciences, Inc.
  • , Ernesto FreireAffiliated withDepartment of Biology, Johns Hopkins University Email author 

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The analysis of protein-protein interactions has attracted the attention of many researchers from both a fundamental point of view and a practical point of view. From a fundamental point of view, the development of an understanding of the signaling events triggered by the interaction of two or more proteins provides key information to elucidate the functioning of many cell processes. From a practical point of view, understanding protein-protein interactions at a quantitative level provides the foundation for the development of antagonists or agonists of those interactions. Isothermal Titration Calorimetry (ITC) is the only technique with the capability of measuring not only binding affinity but the enthalpic and entropic components that define affinity. Over the years, isothermal titration calorimeters have evolved in sensitivity and accuracy. Today, TA Instruments and MicroCal market instruments with the performance required to evaluate protein-protein interactions. In this methods paper, we describe general procedures to analyze heterodimeric (porcine pancreatic trypsin binding to soybean trypsin inhibitor) and homodimeric (bovine pancreatic α-chymotrypsin) protein associations by ITC.

Key words

Protein-protein interaction Thermodynamics Calorimetry Titration Binding Dimerization Dissociation