title: Conformational change in unsolvated Trp-cage protein probed by fluorescence.
abstract: We report the first direct measurements of the unfolding of a protein, Trp-cage, in the gas phase using laser-induced fluorescence of protein ions in a heated quadrupole ion trap. The changes in enthalpy and entropy associated with the observed conformational change are obtained by fitting a two-state model of protein unfolding to the fluorescence intensities plotted versus temperature. The enthalpy and entropy changes for the 2+ and 3+ charge states are greater than the values measured in solution and depend on charge state.
authors.affiliation: The Rowland Institute at Harvard, 100 Edwin H. Land Boulevard, Cambridge, Massachusetts 02142, USA.
authors.forename: Anthony T
authors.initials: AT
authors.lastname: Iavarone
authors.forename: Joel H
authors.initials: JH
authors.lastname: Parks
mesh_terms: D001896:Boron Compounds / Q000737:chemistry; D019277:Entropy; D005453:Fluorescence; D005456:Fluorescent Dyes / Q000737:chemistry; D006358:Hot Temperature; D010455:Peptides / Q000737:chemistry*; D011487:Protein Conformation; D014364:Tryptophan / Q000737:chemistry
chemical_list: C095489:4,4-difluoro-4-bora-3a,4a-diaza-s-indacene; D001896:Boron Compounds; D005456:Fluorescent Dyes; D010455:Peptides; C508725:Trp-cage peptide; D014364:Tryptophan