title: H/D isotope effects in protein thermal denaturation: the case of bovine serum albumin.
abstract: The present work investigates the effects of H/D isotopic substitution on the structural and thermodynamic stability of bovine serum albumin (BSA) in aqueous solution over the temperature range of 5-90 °C. Using far-ultraviolet circular dichroism, we have compared protein unfolding pathways in H(2)O and D(2)O. Our results show that BSA possesses similar conformations in H(2)O and D(2)O at temperatures below 50 °C but follows different unfolding pathways at higher temperatures. The presence of D(2)O retards the occurrence of irreversible thermal denaturation in BSA, as evidenced by a higher onset temperature of 58 °C, in contrast to 50 °C in H(2)O. D(2)O exhibits a protective effect on the domain structure during the early stages of domain denaturation. Following incubation at 90 °C over a period of minutes, D(2)O causes a rapid aggregation of BSA molecules. This behavior is not observed in H(2)O solutions. Meanwhile, H/D substitution does not influence the reversible structural transformation of the protein in a significant manner. Partly renatured BSA in H(2)O and D(2)O undergoes very similar reversible structural transformations during a second heating cycle.
authors.affiliation: Centre de Recherche sur la Matiére Divisée, UMR 6619-CNRS, Université d'Orléans, 1b rue de la Férollerie, 45071 Orléans Cedex 2, France. Ling.Fu@gmail.com
authors.forename: Ling
authors.initials: L
authors.lastname: Fu
authors.forename: Sandrine
authors.initials: S
authors.lastname: Villette
authors.forename: Stéphane
authors.initials: S
authors.lastname: Petoud
authors.forename: Felix
authors.initials: F
authors.lastname: Fernandez-Alonso
authors.forename: Marie-Louise
authors.initials: ML
authors.lastname: Saboungi
mesh_terms: D000818:Animals; D002417:Cattle; D002942:Circular Dichroism; D003903:Deuterium / Q000737:chemistry; D041961:Deuterium Exchange Measurement; D006859:Hydrogen / Q000737:chemistry*; D011489:Protein Denaturation; D017433:Protein Structure, Secondary; D058767:Protein Unfolding; D012710:Serum Albumin, Bovine / Q000737:chemistry*; D013696:Temperature
chemical_list: D012710:Serum Albumin, Bovine; D006859:Hydrogen; D003903:Deuterium