The unfolding of 23kD (P23k) protein isolated from spinach photosystem II particle was studied by high pressure and fluorescence spectroscopy. The thermal equilibrium study indicated that the protein could be totally unfolded by 180 or 160 MPa at 20°C and 3°C, respectively. The standard free energy and standard volume change of the protein for unfolding at 20°C is 23.45 kJ/mol and -150.3 ml/mol, respectively. Kinetics study indicated that at 20°C the activation volume for unfolding, Δ Vu ‡, was negative (-66.2 ml/mol), meanwhile the activation volume for folding, Δ Vf‡, was positive (84. 1 ml/mol). The rate constants for folding and unfolding (K0f, K 0u) were 1.87 s-1 and 1.3 × 10-4 s -1, respectively, these results provide some clues to explain why the protein is so sensitive to pressure.
|Number of pages||5|
|Journal||Acta Biochimica et Biophysica Sinica|
|Publication status||Published - Aug 22 2003|
- Fluorescence spectroscopy
- High pressure technique
- Protein unfolding
ASJC Scopus subject areas