GE Healthcare -
Use of ITC/DSC for the studies of biomolecular stability and interaction of excipients with proteins
Stability of liquid protein formulation is critical for achieving desired therapeutic effect during prolonged storage of biopharmaceuticals. Our ability to predict factors critical to protein stability is limited due to a complex nature of proteins and a broad range of chemical and physical factors contributing to protein destabilization. Therefore optimization of protein stability and understanding of the stabilizing effects of excipients on a molecular level remains a combination of trial-and-error and rational approaches. Several biochemical and biophysical techniques are often needed to profile and optimize protein stability. Biophysical techniques provide data on multiple parameters such as protein homogeneity, specific binding activity and affinity, thermal stability and thermodynamics of protein binding/unfolding throughout the development process.
Differential Scanning and Isothermal Titration Calorimetry (DSC & ITC) offer generic means for assessment of protein stability and investigation of protein-excipient interactions. DSC provides direct information on the thermal stability of a protein. Data on the mid-point of unfolding transition (Tm) along with the temperature at the onset of thermal unfolding and extent of reversibility of unfolding transition tends to be a good indicator of the relative stability of proteins. These parameters allow ranking of different buffers and excipients in terms of their effect on protein stability.
ITC is used to assess binding affinity as well as specific activity of a therapeutic protein in a given formulation. In formulation development knowledge of protein-excipient binding parameters is useful for determining the lowest possible concentration of bound excipient needed to 'saturate' the protein and attain the stabilizing effect. Minimizing the concentration of excipient in a formulation reduces costs as well as the level of additives that will be administered to a patient.
This presentation will give examples of the application of MicroCa™l DSC and ITC to the studies of protein stability and protein-excipient interactions.
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