Technology

What is DSC?

Differential Scanning Calorimetry (DSC) is unsurpassed for understanding the stability of biological systems.  DSC directly measures heat changes that occur in biomolecules during controlled increase or decrease in temperature, making it possible to study materials in their native state.

DSC measures the enthalpy (∆H) of unfolding due to heat denaturation.  A biomolecule in solution is in equilibrium between the native (folded) conformation and its denatured (unfolded) state.  The higher the thermal transition midpoint (Tm), when 50% of the biomolecules are unfolded, the more stable the molecule.  DSC is also used to determine the change in heat capacity (ΔCp) of denaturation.

DSC can elucidate the factors that contribute to the folding and stability of native biomolecules, including hydrophobic interactions, hydrogen bonding, conformational entropy, and the physical environment.

Applications include:

  • Protein stability and folding.
  • Liquid biopharmaceutical formulations.
  • Process development.
  • Protein engineering.
  • Rank order binding.
  • Antibody domain studies.
  • Characterization of membranes, lipids, nucleic acids and micellar systems.
  • Assessment of the effects of structural change on a molecule’s stability.
  • Measurement of ultra-tight molecular interactions (up to 1020 M-1).
  • Assessment of biocomparability during manufacturing.

Why DSC?

  • Ideal for stability and folding studies.
  • Provides insights into mechanisms of unfolding and refolding.
  • Monitors reversibility of thermal processes. 
  • Study molecules in their native state without labeling.  Can be use with solutions that interfere with optical methods including turbid or colored solutions or particulate suspensions.
  • Monitors conformational energetics of proteins and biopolymers
  • Continuously measures excess heat capacity.

The DSC systems from MicroCal are designed and optimized for analysis of biomolecules in solution and are widely used at major pharmaceutical, biotech, academic and government institutions worldwide.  There are thousands of literature citations which use DSC to study the stability of biomolecules.

How does DSC work?

Differential Scanning Calorimetry (DSC) is a powerful analytical tool which directly measures the stability and unfolding of a protein, lipid, or nucleic acid.  In DSC, the biomolecule is heated at a constant rate and there is a detectable heat change associated with thermal denaturation.

In a single DSC experiment, can determine:

  • Transition midpoint - Tm
  • Enthalpy (ΔH) and heat capacity change (ΔCp) associated with unfolding

A biomolecule in aqueous solution is in equilibrium between the native (folded) conformation and its denatured (unfolded) conformation.  The stability of the native state is based on the magnitude of the Gibbs free energy (ΔG) of the system and the thermodynamic relationships between enthalpy (ΔH) and entropy (ΔS) changes.  A positive ΔG indicates the native state is more stable than the denatured state – the more positive the ΔG, the greater the stability.  For a protein to unfold, stabilizing forces need to be broken.  Conformational entropy overcomes stabilizing forces allowing the protein to unfold at temperatures where entropy becomes dominant.

DSC measures ΔH of unfolding due to heat denaturation.  The transition midpoint Tm is the temperature where 50% of the protein is in its native conformation and the other 50% is denatured. The higher the Tm, the more stable the molecule.  During the same experiment DSC also measures the change in heat capacity (ΔCp) for denaturation.  Heat capacity changes associated with protein unfolding are primarily due to changes in hydration of side chains that were buried in the native state, but become solvent exposed in the denatured state.

Many factors are responsible for the folding and stability of native biopolymers, including hydrophobic interactions, hydrogen bonding, conformational entropy, and the physical environment (pH, buffer, ionic strength, excipients, etc.)

View animation of a typical DSC experiment

Reference Lists

DSC – Reviews Reference List

DSC – Instrumentation and Data Analysis Reference List

Need more information? Contact us.