Equilibrium unfolding of class pi glutathione S-transferase.
The equilibrium unfolding transition of class pi glutathione S-transferase, a homodimeric protein, from porcine lung was monitored by spectroscopic methods (fluorescence emission and ultraviolet absorption), and by enzyme activity changes. Solvent (guanidine hydrochloride and urea)-induced denaturation is well described by a two-state model involving significant populations of only the folded dimer and unfolded monomer. Neither a folded, active monomeric form nor stable unfolding intermediates were detected. The conformational stability, delta Gu (H2O), of the native dimer was estimated to be about 25.3 +/- 2 kcal/mol at 20 degrees C and pH6.5.
Department of Chemistry and Biochemistry, Rand Afrikaans University, Johannesburg, South Africa.
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D000818:Animals; D002852:Chromatography, Ion Exchange; D005982:Glutathione Transferase / Q000737:chemistry*; D008168:Lung / Q000201:enzymology; D011487:Protein Conformation; D011489:Protein Denaturation; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet; D013329:Structure-Activity Relationship; D013552:Swine; D013816:Thermodynamics
D005982:Glutathione Transferase