Circular Dichroism Method for Heat Capacity Determination of Proteins

• Cecil L. Jones ^[1] ; Chris Bailey ^[1] ; Kiran Kumar Bheemarti ^[1]
  1. [1] University of South Alabama

     University of South Alabama

     Estados Unidos

     
• Localización: Journal of chemical education, ISSN 0021-9584, Vol. 83, Nº 7, 2006, pág. 1067
• Idioma: inglés
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• Resumen

  • Circular dichroism spectroscopy was used to measure the thermal unfolding of bovine pancreatic ribonuclease A (RNase A) with various concentrations of guanidine hydrochloride (GuHCl). A red shift in transition midpoint temperatures, Tm, occurred with increasing concentration of the strong protein denaturant. van Hoff enthalpy changes, ΔH°, were calculated and plotted as a function of Tm to determine the heat capacity change, ΔCp, for denaturation. A value of 4.02 ± 0.02 kJ mol–1 K–1 was calculated from d( ΔH)/d(ΔTm). Reported values for ΔCp range from 4.2 to 9.6 kJ mol–1 K–1. The shift in Tm for RNase A with increasing concentration of GuHCl suggests that the protein is undergoing substantial changes in its secondary structure.