Effect of chaotropic agents on reversible unfolding of a soybean (Glycine max) seed acid phosphatase.
In this work we examined the effect of urea and guanidinium chloride on the structural stability of a single isoform of soybean seed acid phosphatase, based on the intensity of tryptophan fluorescence as a function of denaturant concentration. The free energy of unfolding, DeltaGu, was calculated at 25 degrees C as a function of the concentrations of both chaotropic agents; the conformational stability, DeltaG (H2O), was determined to be 2.48 kcal mol(-1). Center of mass, determined from analysis of fluorescence data, was used as a parameter to assess conformational changes. Our results indicate that complete enzyme inactivation occurred before full enzyme unfolding in both cases, and suggest that there are differences between the conformational flexibility of the active-site and that of the macromolecule as a whole.
Cavagis
Alexandre Donizeti Martins
AD
Departamento de Bioquímica, Instituto de Biologia, Universidade Estadual de Campinas (UNICAMP), 13083-970, Campinas, São Paulo, Brazil.
Granjeiro
Paulo Afonso
PA
Ferreira
Carmen Veríssima
CV
Aoyama
Hiroshi
H
D000135:Acid Phosphatase / Q000737:chemistry* / Q000378:metabolism; D019791:Guanidine / Q000737:chemistry*; D011489:Protein Denaturation; D017510:Protein Folding; D012639:Seeds / Q000201:enzymology; D013025:Glycine max / Q000201:enzymology*; D013050:Spectrometry, Fluorescence; D013816:Thermodynamics; D014508:Urea / Q000737:chemistry*
D014508:Urea; D000135:Acid Phosphatase; D019791:Guanidine