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Cold denaturation of ubiquitin
B Ibarra-Molero1, G I Makhatadze, J M Sanchez-Ruiz
1Facultad de Ciencias, Departamento de Quimica Fisica, Granada, Spain.
Biochimica Et Biophysica Acta
|February 16, 1999
Summary
Bovine ubiquitin unfolds with heat or cold in high guanidinium hydrochloride concentrations. Thermodynamic models accurately predict this unfolding behavior, showing linear changes in Gibbs energy with guanidine levels.
Area of Science:
- Protein biophysics
- Thermodynamics of protein folding
Background:
- Understanding protein stability is crucial in biochemistry.
- Guanidinium hydrochloride (GdmCl) is a common denaturant used to study protein unfolding.
- Bovine ubiquitin serves as a model protein for biophysical studies.
Purpose of the Study:
- To investigate the temperature-induced unfolding of bovine ubiquitin.
- To examine the effect of varying guanidinium hydrochloride (GdmCl) concentrations on ubiquitin stability.
- To analyze the thermodynamic parameters of protein denaturation.
Main Methods:
- Differential scanning calorimetry (DSC) was employed to measure thermal unfolding.
- Experiments were conducted across a range of GdmCl concentrations.
- Thermodynamic analysis was performed using established models.
Main Results:
- Bovine ubiquitin exhibited both heat and cold-induced denaturation at high GdmCl concentrations.
- The enthalpy of unfolding showed good agreement with the thermodynamic denaturant binding model.
- Unfolding Gibbs energy changed linearly with increasing guanidine concentration.
Conclusions:
- GdmCl can induce cold denaturation in bovine ubiquitin at high concentrations.
- The thermodynamic denaturant binding model effectively describes ubiquitin unfolding in GdmCl.
- Protein stability is modulated by denaturant concentration, following predictable thermodynamic principles.