title: Effect of trifluoroethanol on the conformational stability of a hyperthermophilic esterase: a CD study.
abstract: The conformational stability of the hyperthermophilic esterase AFEST from Archeoglobus fulgidus against the denaturing action of 2,2,2-trifluoroethanol (TFE) has been investigated by means of circular dichroism (CD) measurements. At room temperature far-UV and near-UV CD spectra point out the occurrence of a co-operative transition from the native structure to a denatured state characterized by a high content of alpha-helix. The TFE concentration at half-completion of the transition proves to be 3.5 M (25% v v(-1)), by recording the molar ellipticity at both 222 and 276 nm. Thermal transition curves of AFEST in the absence and in the presence of TFE indicate a significant stability decrease on increasing the TFE concentration. The denaturation temperature is 99 degrees C for native AFEST, but becomes 85 degrees C at 1.4 M TFE (10% v v(-1)), and 56 degrees C at 2.8 M TFE (20% v v(-1)). It is also shown that, even though AFEST is very resistant to temperature, its resistance towards the denaturing action of TFE is similar to that of mesophilic proteins, including an esterase from Escherichia coli, AES. The proposal of a general mechanism for the TFE action on globular proteins leads to a reliable rationale of experimental data.
authors.affiliation: Department of Chemistry, University of Naples Federico II, Via Cintia, 45-80126, Naples, Italy. delvecchio@chemistry.unina.it
authors.forename: Pompea
authors.initials: P
authors.lastname: Del Vecchio
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Graziano
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Granata
authors.forename: Guido
authors.initials: G
authors.lastname: Barone
authors.forename: Luigi
authors.initials: L
authors.lastname: Mandrich
authors.forename: Mosè
authors.initials: M
authors.lastname: Rossi
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Manco
mesh_terms: D000818:Animals; D002942:Circular Dichroism; D004795:Enzyme Stability; D004950:Esterases / Q000737:chemistry*; D011487:Protein Conformation; D013696:Temperature; D013816:Thermodynamics; D014270:Trifluoroethanol / Q000737:chemistry*
chemical_list: D014270:Trifluoroethanol; D004950:Esterases