title: Chemical denaturation of the elongation factor 1alpha isolated from the hyperthermophilic archaeon Sulfolobus solfataricus.
abstract: The stability against chemical denaturants of the elongation factor EF-1alpha (SsEF-1alpha), a protein isolated from the hyperthermophilic archaeon Sulfolobus solfataricus has been characterized in detail. Indeed, the atypical shape of the protein structure and the unusual living conditions of the host organism prompted us to analyze the effect of urea and guanidine hydrochloride (GuHCl) on the GDP complex of the enzyme (SsEF-1alpha x GDP) by fluorescence and circular dichroism. These studies were also extended to the nucleotide-free form of the protein (nfSsEF-1alpha). Interestingly, the experiments show that the denaturation curves of both SsEF-1alpha forms present a single inflection point, which is indicative of a cooperative unfolding process with no intermediate species. Moreover, the chemically induced unfolding process of both SsEF-1alpha x GDP and nfSsEF-1alpha is fully reversible. Both SsEF-1alpha forms exhibit remarkable stability against urea, but they do not display a strong resistance to the denaturing action of GuHCl. These findings suggest that electrostatic interactions significantly contribute to SsEF-1alpha stability.
authors.affiliation: Dipartimento delle Scienze Biologiche, Sezione di Biostrutture, Università degli Studi di Napoli Federico II, I-80134 Napoli, Italy.
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Granata
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Graziano
authors.forename: Alessia
authors.initials: A
authors.lastname: Ruggiero
authors.forename: Gennaro
authors.initials: G
authors.lastname: Raimo
authors.forename: Mariorosario
authors.initials: M
authors.lastname: Masullo
authors.forename: Paolo
authors.initials: P
authors.lastname: Arcari
authors.forename: Luigi
authors.initials: L
authors.lastname: Vitagliano
authors.forename: Adriana
authors.initials: A
authors.lastname: Zagari
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000302:isolation & purification*; D004795:Enzyme Stability / Q000187:drug effects; D019791:Guanidine / Q000737:chemistry / Q000494:pharmacology; D006358:Hot Temperature; D020648:Peptide Elongation Factor 1 / Q000737:chemistry* / Q000302:isolation & purification*; D011487:Protein Conformation / Q000187:drug effects; D011489:Protein Denaturation / Q000187:drug effects; D048229:Sulfolobus solfataricus / Q000737:chemistry*; D013816:Thermodynamics; D014508:Urea / Q000737:chemistry / Q000494:pharmacology
chemical_list: D001426:Bacterial Proteins; D020648:Peptide Elongation Factor 1; D014508:Urea; D019791:Guanidine