Thermodynamics of staphylococcal nuclease denaturation. I. The acid-denatured state.


Abstract

Using high-sensitivity differential scanning calorimetry, we reexamined the thermodynamics of denaturation of staphylococcal nuclease. The denaturational changes in enthalpy and heat capacity were found to be functions of both temperature and pH. The denatured state of staphylococcal nuclease at pH 8.0 and high temperature has a heat capacity consistent with a fully unfolded protein completely exposed to solvent. At lower pH values, however, the heat capacity of the denatured state is lower, resulting in a lower delta Cp and delta H for the denaturation reaction. The acid-denatured protein can thus be distinguished from a completely unfolded protein by a defined difference in enthalpy and heat capacity. Comparison of circular dichroism spectra suggests that the low heat capacity of the acid-denatured protein does not result from residual helical secondary structure. The enthalpy and heat capacity changes of denaturation of a less stable mutant nuclease support the observed dependence of delta H on pH. Study holds ProTherm entries: 2945, 2946, 2947, 2948, 2949, 2950, 2951, 2952 Extra Details: additive : EDTA(1 mM),measurements were made in the presence of 0.1M NaCl denatured state; molten globule; protein denaturation;,structural intermediate; unfolding

Submission Details

ID: gwKz9XpQ

Submitter: Connie Wang

Submission Date: April 24, 2018, 8:20 p.m.

Version: 1

Publication Details
Carra JH;Anderson EA;Privalov PL,Protein Sci. (1994) Thermodynamics of staphylococcal nuclease denaturation. I. The acid-denatured state. PMID:8069223
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