1.
pH-Dependent urea-induced unfolding of stem bromelain: unusual stability against urea at neutral pH.
Biochemistry (Mosc)
; 74(12): 1337-43, 2009 Dec.
Artigo
em Inglês
| MEDLINE
| ID: mdl-19961414
RESUMO
Equilibrium unfolding of stem bromelain (SB) with urea as a denaturant has been monitored as a function of pH using circular dichroism and fluorescence emission spectroscopy. Urea-induced denaturation studies at pH 4.5 showed that SB unfolds through a two-state mechanism and yields DeltaG (free energy difference between the fully folded and unfolded forms) of approximately 5.0 kcal/mol and C(m) (midpoint of the unfolding transition) of approximately 6.5 M at 25 degrees C. Very high concentration of urea (9.5 M) provides unusual stability to the protein with no more structural loss and transition to a completely unfolded state.