title: Solvation in protein (un)folding of melittin tetramer-monomer transition.
abstract: Protein structural integrity and flexibility are intimately tied to solvation. Here, we examine the effect that changes in bulk and local solvent properties have on protein structure and stability. We observe the change in solvation of an unfolding of the protein model, melittin, in the presence of a denaturant, trifluoroethanol. The peptide system displays a well defined transition in that the tetramer unfolds without disrupting the secondary or tertiary structure. In the absence of local structural perturbation, we are able to reveal exclusively the role of solvation dynamics in protein structure stabilization and the (un)folding pathway. A sudden retardation in solvent dynamics, which is coupled to the change in protein structure, is observed at a critical trifluoroethanol concentration. The large amplitude conformational changes are regulated by the local solvent hydrophobicity and bulk solvent viscosity.
authors.affiliation: Physical Biology Center for Ultrafast Science and Technology, Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, CA 91125, USA.
authors.forename: Christina M
authors.initials: CM
authors.lastname: Othon
authors.forename: Oh-Hoon
authors.initials: OH
authors.lastname: Kwon
authors.forename: Milo M
authors.initials: MM
authors.lastname: Lin
authors.forename: Ahmed H
authors.initials: AH
authors.lastname: Zewail
mesh_terms: D001704:Biopolymers / Q000737:chemistry*; D008555:Melitten / Q000737:chemistry*; D017510:Protein Folding; D017433:Protein Structure, Secondary; D012997:Solvents / Q000737:chemistry; D013050:Spectrometry, Fluorescence; D014270:Trifluoroethanol / Q000737:chemistry; D014783:Viscosity
chemical_list: D001704:Biopolymers; D012997:Solvents; D008555:Melitten; D014270:Trifluoroethanol