title: Protein folding: the stepwise assembly of foldon units.
abstract: Equilibrium and kinetic hydrogen exchange experiments show that cytochrome c is composed of five foldon units that continually unfold and refold even under native conditions. Folding proceeds by the stepwise assembly of the foldon units rather than one amino acid at a time. The folding pathway is determined by a sequential stabilization process; previously formed foldons guide and stabilize subsequent foldons to progressively build the native protein. Four other proteins have been found to show similar behavior. These results support stepwise protein folding pathways through discrete intermediates.
authors.affiliation: Johnson Research Foundation, Department of Biochemistry and Biophysics, University of Pennsylvania School of Medicine, Philadelphia, PA 19104-6059, USA. hamity@hx2.med.upenn.edu
authors.forename: Haripada
authors.initials: H
authors.lastname: Maity
authors.forename: Mita
authors.initials: M
authors.lastname: Maity
authors.forename: Mallela M G
authors.initials: MM
authors.lastname: Krishna
authors.forename: Leland
authors.initials: L
authors.lastname: Mayne
authors.forename: S Walter
authors.initials: SW
authors.lastname: Englander
mesh_terms: D000818:Animals; D045304:Cytochromes c / Q000737:chemistry*; D041961:Deuterium Exchange Measurement; D006736:Horses / Q000378:metabolism*; D008958:Models, Molecular; D011487:Protein Conformation; D017510:Protein Folding; D021122:Protein Subunits / Q000737:chemistry*
chemical_list: D021122:Protein Subunits; D045304:Cytochromes c