Mutational Analysis of the BPTI Folding Pathway
Over the past three decades, considerable effort has been focused on elucidating the mechanisms by which polypeptide chains fold into well-defined three-dimensional structures (Kim & Baldwin, 1990; Creighton, 1992a; Mattthews, 1993). Major goals of these studies include the identification and characterization of partially folded intermediates and the analysis of transition states that represent the energetic barriers in the folding mechanism. Recently, there has been great progress in the structural analysis of folding intermediates by high resolution NMR spectroscopy of intermediate analogs and native proteins that have been isotopically-labeled during refolding. Structural analysis alone, however, is not sufficient to determine why particular intermediates form or what types of interactions stabilize their conformations. By their very nature, transition states are even more difficult to characterize directly. Questions about folding energetics and the roles of individual interactions in determining the folding mechanism can often be addressed by studying the folding of protein variants that differ by relatively small perturbations of the covalent structure. Recently-developed genetic techniques have made it possible to alter virtually any amino acid residue in a protein, and mutational methods have now been used to study the folding mechanisms of several proteins (Fersht et al., 1992; Goldenberg 1992a; Jennings et al., 1992). We describe here some of our recent work using amino acid replacements to study the folding of a particularly well-characterized protein, bovine pancreatic trypsin inhibitor (BPTI).
KeywordsDirect Reduction Amino Acid Replacement Folding Pathway Folding Intermediate Bovine Pancreatic Trypsin Inhibitor
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- Creighton, T. E., 1978, Experimental studies of protein folding and unfolding., Prog. Biophys. Mol. Biol. 22: 221–298.Google Scholar
- Creighton, T. E.,1992a, Protein Folding, New York: W.H. Freeman.Google Scholar
- Creighton, T. E., 1992b, Protein folding pathways determined using disulfide bonds, BioEssays 14: 195–199.Google Scholar
- Goldenberg, D. P., 1992a, Mutational analysis of protein folding and stability, in Protein Folding, T. E. Creighton (ed.), pp. 353–403, New York: W.H. Freeman.Google Scholar
- States, D. J., Dobson, C. M., Karplus, M., and Creighton, T. E., 1984, A new two-disulphide intermediate in the refolding of reduced bovine pancreatic trypsin inhibitor, J. Mol. Biol. 174:411-–418.Google Scholar
- van Mierlo, C. P. M., Darby, N. J., Neuhaus, D., and Creighton, T. E., 199la, (14–38,30–51) Double-disulfide intermediate in folding of bovine pancreatic trypsin inhibitor: A two-dimensional 1H nuclear magnetic resonance study, J. Mol. Biol. 222: 353–371.Google Scholar
- van Mierlo, C. P. M., Darby, N. J., Keeler, J., Neuhaus, D., and Creighton, T. E., 1993, Partially folded conformation of the (30–51) intermediate in the disulfide folding pathway of bovine pancreatic trypsin inhibitor: 1H and 15N resonance assignments and determination of backbone dynamics form 15N relaxation measurements, J.Mol.Bio1. 229: 1125–1146.CrossRefGoogle Scholar
- van Mierlo, C. P. M., Kemmink, J., Neuhaus, D., Darby, N. J., and Creighton, T. E., 1994, 1H NMR analysis of the partly-folded non-native two-disulfide intermediates (30–51,5–14) and (30–51,5–38) in the folding pathway of bovine pancreatic trypsin inhibitor, J. Mol. Biol. 235: 1044–1061.Google Scholar