The Observed Change in Heat Capacity Accompanying the Thermal Unfolding of Proteins Depends on the Composition of the Solution and on the Method Employed To Change the Temperature of Unfolding
- 1 January 1996
- journal article
- research article
- Published by American Chemical Society (ACS) in Biochemistry
- Vol. 35 (9) , 3059-3062
- https://doi.org/10.1021/bi952198j
Abstract
The apparent change in heat capacity, ΔCp, accompanying the thermally induced unfolding of lysozyme and of ribonuclease A was determined by means of differential scanning calorimetry in dilute aqueous buffer containing one of the following added solutes: 0.5 M or 1.0 M sucrose, 1.0 M glycine, 0.5 M, 1.0 M, or 2.0 M guanidinium chloride, 10% glycerol, or 0.5 M NaCl over a pH range. In each system the temperature of half-completion, t1/2, of the unfolding transition was varied by varying the pH. The resulting enthalpies of denaturation were linearly dependent on t1/2 for each solvent system. The resulting values of ΔCp for each protein showed variations of almost 2-fold. Such large variations in the sensitivity of the proteins to temperature changes are not readily interpreted.Keywords
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