title: Extremely rapid protein folding in the absence of intermediates.
abstract: Here we used the cold-shock protein CspB from Bacillus subtilis to study protein folding at an elementary level. The thermodynamic stability of this small five-stranded beta-barrel protein is low, but unfolding and refolding are extremely rapid reactions. In 0.6 M urea the time constant of refolding is about 1.5 ms, and at the transition midpoint (4 M urea) the folded and unfolded forms equilibrate in less than 100 ms. Both the equilibrium unfolding transition and the folding kinetics are perfectly described by a N<-->U two-state model. The validity of this model was confirmed by several kinetic tests. Folding intermediates could neither be detected at equilibrium nor in the folding kinetics. We suggest that the extremely rapid folding of CspB and the absence of folding intermediates are related phenomena.
authors.affiliation: Laboratorium für Biochemie, Universität Bayreuth, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Schindler
authors.forename: M
authors.initials: M
authors.lastname: Herrler
authors.forename: M A
authors.initials: MA
authors.lastname: Marahiel
authors.forename: F X
authors.initials: FX
authors.lastname: Schmid
mesh_terms: D001412:Bacillus subtilis / Q000378:metabolism*; D001426:Bacterial Proteins / Q000737:chemistry*; D002942:Circular Dichroism; D004355:Drug Stability; D007700:Kinetics; D011489:Protein Denaturation; D017510:Protein Folding; D017433:Protein Structure, Secondary; D013056:Spectrophotometry, Ultraviolet; D013816:Thermodynamics; D013997:Time Factors; D014508:Urea / Q000494:pharmacology
chemical_list: D001426:Bacterial Proteins; C077188:cold-shock protein CspB, Bacteria; D014508:Urea