Relationship between the native-state hydrogen exchange and folding pathways of a four-helix bundle protein.
The hydrogen exchange behavior of a four-helix bundle protein in low concentrations of denaturant reveals some partially unfolded forms that are significantly more stable than the fully unfolded state. Kinetic folding of the protein, however, is apparently two-state in the absence of the accumulation of early folding intermediates. The partially unfolded forms are either as folded as or more folded than the rate-limiting transition state and appear to represent the major intermediates in a folding and unfolding reaction. These results are consistent with the suggestion that partially unfolded intermediates may form after the rate-limiting step for small proteins with apparent two-state folding kinetics.
Chu
Ruiai
R
Laboratory of Biochemistry, Building 37, Room 6114E, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA.
Pei
Wuhong
W
Takei
Jiro
J
Bai
Yawen
Y
D000577:Amides; D001059:Apoproteins / Q000737:chemistry* / Q000235:genetics; D003573:Cytochrome b Group / Q000737:chemistry* / Q000235:genetics; D003903:Deuterium; D019791:Guanidine / Q000737:chemistry; D006859:Hydrogen / Q000737:chemistry*; D006860:Hydrogen Bonding; D007700:Kinetics; D008956:Models, Chemical; D016297:Mutagenesis, Site-Directed; D011489:Protein Denaturation / Q000235:genetics; D015202:Protein Engineering / Q000379:methods; D017510:Protein Folding; D017433:Protein Structure, Secondary / Q000235:genetics; D011522:Protons; D013816:Thermodynamics
D000577:Amides; D001059:Apoproteins; D003573:Cytochrome b Group; D011522:Protons; D006859:Hydrogen; D003903:Deuterium; D019791:Guanidine