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Phage T4 lysozyme. Physical properties and reversible unfolding
Biochimica Et Biophysica Acta
|March 28, 1975
Summary
This study characterizes purified T4 lysozyme, revealing its spectral properties and reversible unfolding. T4 lysozyme exhibits significant helix content and pH-dependent denaturation, crucial for understanding protein stability.
Area of Science:
- Biochemistry
- Molecular Biology
- Biophysics
Background:
- Phage T4 lysozyme is vital for genetic code studies.
- Limited characterization exists for purified T4 lysozyme.
Purpose of the Study:
- Determine spectral properties of native T4 lysozyme.
- Characterize the unfolding transition of T4 lysozyme.
- Investigate pH dependence of chemical and thermal denaturation.
Main Methods:
- UV absorption spectroscopy
- Solvent perturbation difference spectroscopy
- Circular dichroism (CD) and ORD spectroscopy
- Fluorescence spectroscopy
- Guanidine hydrochloride denaturation
- Thermal denaturation
Main Results:
- Aromatic amino acids in T4 lysozyme are largely solvent-exposed.
- Native T4 lysozyme possesses a high helical content.
- Chemical denaturation (GdnHCl) shows pH dependence (2.7 M at pH 5, 1.7 M at pH 2.5).
- Denaturation transitions are fully reversible.
- Thermal denaturation studies indicate increasing Tm, ΔH unf, and ΔS unf with rising pH.
Conclusions:
- Spectral properties provide insights into T4 lysozyme structure and solvent accessibility.
- T4 lysozyme exhibits reversible unfolding with significant pH-dependent stability.
- Thermodynamic parameters of thermal denaturation are pH-sensitive.