Estimation of the folding/unfolding energetics of marginally stable proteins using differential scanning calorimetry

Donald T. Haynie, Ernesto Freire

Research output: Contribution to journalArticlepeer-review

Abstract

We demonstrate a method for obtaining accurate estimates of the thermodynamic parameter values characteristic of a two-state folding/unfolding transition under conditions in which the onset of cold denaturation prevents the native state from being fully populated at any temperature. This situation occurs for proteins exhibiting low thermal stability, which may be intrinsic, the result of amino acid substitution, or the consequence of protein-solvent interactions (e.g., extremes of pH, the presence of denaturants, extremes of ionic strength). Conventional analysis of calorimetric scans obtained under such conditions yields erroneous values for the enthalpy, entropy, and heat capacity changes characteristic of the folding/unfolding transition of the protein. This paper describes for the first time the weighted average enthalpy function. In contrast to the van′t Hoff and calorimetric enthalpies, the weighted average enthalpy yields thermodynamic parameter values which differ by less than 5% from the true value, even for situations in which the population of molecules in the native state at the start of the transition is half of the total.

Original languageEnglish (US)
Pages (from-to)33-41
Number of pages9
JournalAnalytical biochemistry
Volume216
Issue number1
DOIs
StatePublished - Jan 1994

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology
  • Cell Biology

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