title: Folding pathway mediated by an intramolecular chaperone.
abstract: The N-terminal propeptide of subtilisin, a serine protease, functions as an intramolecular chaperone which is crucial for proper folding of the active enzyme. This nascent N-terminal propeptide is removed after completion of the folding process. Here we present a possible pathway by which intramolecular chaperones mediate protein folding. Using circular dichroism to analyze acid-denatured subtilisin we have identified a folding-competent state which can refold to an active conformation in the absence of the propeptide. Earlier work had shown that guanidine hydrochloride-denatured subtilisin was in a state incapable of folding in absence of its propeptide. Comparison of the folding-incompetent and folding-competent states indicates that refolding is facilitated by the presence of residual structure present only in the folding-competent state. The analysis further indicates that the propeptide is essential for inducing this state. Therefore the folding-competent state may lie on--or be in rapid equilibrium with an intermediate on--the folding pathway of subtilisin. In the absence of the propeptide, formation of such a state--and hence refolding--is extremely slow.
authors.affiliation: Department of Biochemistry, Robert Wood Johnson Medical School, University of Medicine and Dentistry of New Jersey, Piscataway 08854.
authors.forename: U
authors.initials: U
authors.lastname: Shinde
authors.forename: Y
authors.initials: Y
authors.lastname: Li
authors.forename: S
authors.initials: S
authors.lastname: Chatterjee
authors.forename: M
authors.initials: M
authors.lastname: Inouye
mesh_terms: D000595:Amino Acid Sequence; D066298:In Vitro Techniques; D007700:Kinetics; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000737:chemistry; D011489:Protein Denaturation; D011498:Protein Precursors / Q000737:chemistry*; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D013329:Structure-Activity Relationship; D013381:Subtilisins / Q000737:chemistry*
chemical_list: D009842:Oligopeptides; D011498:Protein Precursors; D013381:Subtilisins