Using heat conduction microcalorimetry to study thermal aggregation kinetics of proteins

Abstract

The thermally induced irreversible aggregation of a monoclonal antibody in different pH buffers was investigated using different techniques such as micro-differential scanning calorimetry (micro-DSC), size exclusion HPLC (SEC) and isothermal microcalorimetry. The kinetics of aggregation of the protein was analyzed in terms of a Lumry–Eyring model proceeding via a non-native conformational state. The rate constants and reaction enthalpies of unfolding and consequent aggregation were obtained by fitting the isothermal microcalorimetric and SEC data based on proposed aggregation mechanisms. The consistency of rate constants obtained via isothermal microcalorimetry and SEC indicates it is possible to deconvolute the observed microcalorimetry power–time data obtained from thermally induced protein aggregation.