title: Is an intermediate state populated on the folding pathway of ubiquitin?
abstract: In the last couple of years, there has been increasing debate as to the presence and role of intermediate states on the folding pathways of several small proteins, including the 76-residue protein ubiquitin. Here, we present detailed kinetic studies to establish whether an intermediate state is ever populated during the folding of this protein. We show that the differences observed in previous studies are attributable to the transient aggregation of the protein during folding. Using a highly soluble construct of ubiquitin, which does not aggregate during folding, we establish the conditions in which an intermediate state is sufficiently stable to be observed by kinetic measurements.
authors.affiliation: Chemistry Department, Centre for Protein Engineering, Lensfield Road, Cambridge CB2 1EW, UK.
authors.forename: Heather M
authors.initials: HM
authors.lastname: Went
authors.forename: Claudia G
authors.initials: CG
authors.lastname: Benitez-Cardoza
authors.forename: Sophie E
authors.initials: SE
authors.lastname: Jackson
mesh_terms: D000595:Amino Acid Sequence; D019791:Guanidine / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D011189:Potassium Chloride / Q000737:chemistry; D011489:Protein Denaturation; D017510:Protein Folding; D011994:Recombinant Proteins / Q000737:chemistry; D013050:Spectrometry, Fluorescence; D013431:Sulfates / Q000737:chemistry; D025801:Ubiquitin / Q000737:chemistry*; D014508:Urea / Q000737:chemistry
chemical_list: D011994:Recombinant Proteins; D013431:Sulfates; D025801:Ubiquitin; D011189:Potassium Chloride; D014508:Urea; D019791:Guanidine