Phi-values for BPTI folding intermediates and implications for transition state analysis.
Amino acid replacements were used to probe the roles of 14 sites in two well-characterized intermediates in the folding pathway of bovine pancreatic trypsin inhibitor (BPTI). One of these intermediates contains one of the three disulfides found in the native protein (30--51). NMR studies have shown that approximately two-thirds of this polypeptide has a native-like conformation. The other intermediate contains two native disulfides (30--51 and 5--55) and has a fully folded conformation. The phi-values for a majority of residues were <1, indicating that the native protein was significantly more destabilized than either intermediate even when the altered residue was located in a well-ordered region of the intermediate. These observations suggest that folding intermediates and transition states may generally be more structured than indicated by phi-values alone.
Bulaj
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Department of Biology, University of Utah, 257 South 1400 East, Salt Lake City, Utah 84112-0840, USA.
Goldenberg
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DP
D019943:Amino Acid Substitution / Q000235:genetics; D000818:Animals; D007611:Aprotinin / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D002417:Cattle; D004220:Disulfides / Q000378:metabolism; D007700:Kinetics; D008958:Models, Molecular; D009154:Mutation / Q000235:genetics; D011487:Protein Conformation; D011489:Protein Denaturation; D017510:Protein Folding; D013816:Thermodynamics
D004220:Disulfides; D007611:Aprotinin