title: The effect of surface charge balance on thermodynamic stability and kinetics of refolding of firefly luciferase.
abstract: Thermodynamic stability and refolding kinetics of firefly luciferase and three representative mutants with depletion of negative charge on a flexible loop via substitution of Glu by Arg (ER mutant) or Lys (EK mutant) as well as insertion of another Arg in ER mutants (ERR mutant) was investigated. According to thermodynamic studies, structural stability of ERR and ER mutants are enhanced compared to WT protein, whereas, these mutants become prone to aggregation at higher temperatures. Accordingly, it was concluded that enhanced structural stability of mutants depends on more compactness of folded state, whereas aggregation at higher temperatures in mutants is due to weakening of intermolecular repulsive electrostatic interactions and increase of intermolecular hydrophobic interactions. Kinetic results indicate that early events of protein folding are accelerated in mutants.
authors.affiliation: Department of Biophysics & Biochemistry, Faculty of Biological Sciences, Tarbiat Modares University, P.O. Box, 14115-175 Tehran, Iran.
authors.forename: Khosrow
authors.initials: K
authors.lastname: Khalifeh
authors.forename: Bijan
authors.initials: B
authors.lastname: Ranjbar
authors.forename: Bagher Said
authors.initials: BS
authors.lastname: Alipour
authors.forename: Saman
authors.initials: S
authors.lastname: Hosseinkhani
mesh_terms: D019943:Amino Acid Substitution; D000818:Animals; D048888:Fireflies / Q000378:metabolism; D007700:Kinetics; D049409:Luciferases, Firefly / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D058849:Protein Refolding; D055550:Protein Stability; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013816:Thermodynamics; D014508:Urea / Q000737:chemistry
chemical_list: D011994:Recombinant Proteins; D014508:Urea; D049409:Luciferases, Firefly