臺灣博碩士論文加值系統

由GroEL-GroES所組成的伴護子蛋白質(chaperonin protein)系統，對於幫助不同蛋白質回到其自然態(native state)的功能是已知且高度研究的。然而對於伴護子蛋白質如何辨識目標蛋白質的不同狀態，與其中的交互作用的了解仍是相當的少。雖有研究結果顯示，伴護子蛋白會辨識與結合於非自然態(partially structured state)或錯誤摺疊(misfold)態的目標蛋白質。但越來越多的證據顯示，GroEL與自然態的目標蛋白質間也具有其交互作用現象。因此在本篇論文中，我們選擇human acidic fibroblast growth factor (hFGF-1)為目標蛋白，探討其在自然態下與GroEL間交互作用的現象與機制。
由hFGF-1於不同條件下(有無GroEL)進行的穩定態螢光與CD光譜實驗結果顯示，hFGF-1在自然態下的確會與GroEL結合，且GroEL會造成hFGF-1穩定度下降的現象。當配合其他如gel filtration與酵素裂解作用等實驗時，則顯示了GroEL與hFGF-1的結合會因ATP存在而有釋放的現象。且從GroEL造成hFGF-1上殘基於1H-15N化學位移擾動(perturbation)的結果中發現，此種交互作用的確會受到溶液中帶電分子如：Sucrose octa sulfate(SOS)的競爭與影響。後我們更利用多維核磁共振光譜技術，監測hFGF-1在有無GroEL存在的條件下，氫氘交換動力學實驗，藉由分析GroEL對hFGF-1各殘基的影響，對此兩種蛋白質間交互作用的性質有更進一步的了解。

摘要························1
第一章 簡 介 ··················2
1.1 蛋白質的摺疊··················2
1.2監護者蛋白質(GroEL-GroES)···········12
1.3人類纖維母細胞生長因子(hFGF-1) ·········21
1.4氫-氘交換動力學·················24
第二章 材料與方法 ················26
2.1 GroEL、GroES蛋白質之表現···········26
2.2 GroEL、GroES蛋白質之純化與濃縮········32
2.3 GroEL、GroES蛋白質之基本性質鑑定·······38
2.4 hFGF-1蛋白質之表現··············46
2.5 hFGF-1蛋白質之純化與濃縮···········48
2.6 hFGF-1蛋白質之基本性質鑑定··········53
2.7 GroEL蛋白質性質之探討·············55
2.8 hFGF-1與GroEL交互作用之探討·········58
2.9 hFGF-1與GroEL作用位置之探討(核磁共振光譜實驗)
······················72
第三章 結果與討論 ················81
3.1 hFGF-1、GroEL、GroES蛋白質之表現與純化····81
3.2 hFGF-1、GroEL、GroES蛋白質之基本性質鑑定 ···89
3.3 GroEL蛋白質之性質之探討···········94
3.4 hFGF-1與GroEL交互作用之探討·········101
3.5 hFGF-1與GroEL作用位置之探討(核磁共振光譜實驗)
·······················124
第四章 結論 ···················148
Reference····················149

Abkevich, V.I.; Gutin, A.M.; Shakhanovich, E. “Specific Nucleus as the Transition-State for Protein-Folding - Evidence from the Lattice Model” Biochemistry, 1994, 33, 10026.
Agard, D. A. “To fold or not to fold” Science, 1993, 260, 1903.
Anfinsen, C. B. “Principles that govern the folding of protein chains” Science, 1973, 181, 223.
Anfinsen, C.B. “Principles that govern the folding of protein chains” science, 1973, 181, 223.
Arrington, G.B.; Robertson, A.D. J. Mol. Biol., 2000, 296, 1307.
Arunkumar, A.I.; Kumar, T.K.; Srisailam, S.; Kathir, K.M.; Wang, H.M.; Leena, P.S., Chi, Y.H.; Yu, C. “Oligomerization of acidic fibroblast growth factor is not a prerequisite for its cell proliferation activity” Protein Sci, 2002, 11, 1050.
Bai, Y.; Sosnick, T.R.; Mayne, L. and Englander, S.W. “Protein- folding intermediates by native-state hydrogen-exchange” FASEB, 1995, 9, A1239.
Bai, Y.W.; Milne, J.S.; Mayne, L. and Englander, S.W. “Protein stability parameters measured by hydrogen-exchange” Proteins: Struct. Funct. Genet., 1994, 20, 4.
Baldwin, R.L. “Pulsed H/D exchange studies of folding intermediates” Curr. Opin. Struct. Biol., 1993, 3, 84.
Baldwin, R.L. “The Nature of Protein-Folding Pathways - The Classical Versus the New View” J. Biomolecular NMR, 1995, 5, 103.
Baldwin, R.L. “Why Is Protein-Folding So Fast” Proc. Natl. Acad. Sci. USA., 1996, 93, 2627.
Braig, K. “Chaperonins” Curr. Opin. Struct. Biol., 1998, 8, 159.
Braig, K., Adams, P. D. and Brunger, A-T. “Conformational variability in the refined structure of the chaperonin GroEL at 2.8°A resolution” Nature Struc. Biol., 1995, 2, 1083.
Braig, K., Otwinouiski, Z., Hegde, R., Boisvert, D. C., Joachimiak, A., Horwich, A. L. and Sigler, P. B., “The crystal structure of the bacterial chaperonin GroEL at 2.8 °A” Nature, 1994, 371, 378.
Briag, K., Simon, M., Furoya, F., Hainfeld, J. F. and Horwich, A. L. “A polypeptide bound by the Chaperonin GroEL is localized within a central cavity” Proc. Natl. Acad. Sci., USA., 1993, 90, 3978.
Bryngelson, J.D.; Onuchich, J.N.; Socci, N.D.; Wolynes, P.G. “Funnels, Pathways, and the Energy Landscape of Protein-Folding - A Synthesis” Protein Struc. Funct. Genet., 1995, 21, 167.
Burke, C.J.; Volkin, D.B.; Mach, H.; Middaugh, C.R. “Effect of polyanions on the unfolding of acdic fibroblast growth factor” Biochemistry, 1993, 32, 6419.
Camacho, C.J.; Thirumalai, D. “Modeling the Role of Disulfide Bonds in Protein-Folding - Entropic Barriers and Pathways” Proteins: Struc.Funct. Genet., 1995, 22, 27.
Camacho, C.J; Thirumalai, D. “Kinetics and Thermodynamics of Folding in Model Proteins” Proc. Natl. Acad. Sci., USA, 1993, 6369
Carlisch, A.; Karplus, M. “Molecular dynamics simulation of protein denaturation: solvation of the hydrophobic cores and secondary structure of barnase” Proc. Natl. Acad. Sci., USA., 1994, 91, 1746.
Chamberlain, A.K.; Marqusee, S. “Touring the landscapes: Partially folded proteins examined by hydrogen exchange” Structure, 1999, 5, 859.
Chen, L. and Sigler P. B. “The crystal structure of a GroEL /peptide complex: Plasticity as a basis for substrate diversity” Cell, 1999, 99, 757.
Clarke, J.; Itzaki, L.S. “Hydrogen exchange and protein folding” Curr. Opin. Struct. Biol., 1998, 8, 112.
Colon, W.; Roder, H. “Kinetic Intermediates in the Formation of the Cytochrome-C Molten Globule” Nat. Struc. Biol., 1996, 3, 1019.
Creighton, T. E. “Protein Folding” Biochem.J., 1990, 270, 1.
Creighton, T.E. “Experimental studies of protein folding and unfolding” Prog. Biophys. Mol. Biol., 1978, 33, 231.
Creighton, T.E. “Protein folding: does diffusion determine the folding rate” Curr. Biol., 1997, 7, R380.
Dabora, J.M.; Sanyal, G.; Middaugh, C.R. “Effect of polyanions on the refolding of human acidic fibroblast growth factor” Journal of biological chemistry, 1991, 266, 23637.
Dalby, P.A.; Oliverberg, M.; Fersht, A.R. “Folding Intermediates of Wild-Type and Mutants of Barnase - I - Use of Phi-Value Analysis and M-Values to Probe the Cooperative Nature of the Folding Preequilibrium” J. Mol. Biol., 1998, 276, 625.
DiGabriele, A.D.; Lax, I.; Chen, D.I.; Svahn, C.M.; Jaye, M.; Schlessinger, J.; Hendrickson, W.A. ”Structure of a heparin-linked biologically active dimer of fibroblast growth factor” Nature, 1998, 393, 812.
Dill, K.A.; Chan, H.S. “From Levinthal to Pathways to Funnels” Nat. Struc. Biol., 1997, 4, 10.
Dill, K.A.; Chan, H.S. “From Levinthal to Pathways to Funnels” Nature Struc. Biol., 1997, 4, 10.
Dobson, C.M.; Sali, A. and Karplus. M. “Protein - Folding - A Perspective from Theory and Experiment” Angew. Chem. Int. Ed., 1998, 37, 868.
Eggerer, J. “Hysteretic behaviour of citrate synthase. Site-directed limited proteolysis” Eur. J. Biochem, 1984, 143, 205.
Elezer, D.; Yao, J.; Dyson, H.J.; Wright, P.E. “Structural and Dynamic Characterization of Partially Folded States of Apomyoglobin and Implications for Protein-Folding” Nat. Struc. Biol., 1998, 5, 148.
Ellis, R. J. “Steric chaperones” Trends Biochem, Sci., 1998, 23, 43.
Englander, J.J.; Mayne, L.; Milne, J.S. and Englander, S.W. “Structure and energy change in hemoglobin by hydrogen-exchange labeling“ Methods Enzymol., 1994, 259, 344.
Englander, S.W., Mayne, L., Bai, Y. and Sosnick, T.R. “Hydrogen exchange: The modern legacy of Linderstrom-Lang” Protein Sci., 1997, 6, 1101.
Englander, S.W.; Kallenbach, N.R. Q. Rev. Biophys., 1983, 16, 521.
Englander, S.W.; Mayne, L. “Protein Folding Studied Using Hydrogen-Exchange Labeling and 2-Dimensional NMR” Ann. Rev. Biophys. Biomol. Struct., 1992, 21, 243.
Englander, S.W.; Mayne, L. “Protein folding studied using hydrogen-exchange labeling and 2-dimensional NMR” Annu. Rev. Biophys. Biomol. Struct., 1992, 21, 243.
Englander, S.W.; Sosnick, T.R.; Englander, J.J. and Mayne, L. “Mechanisms and uses of hydrogen exchange” Curr. Opin. Struct. Biol., 1996, 6, 18.
Fenton, W.A., Kashi, Y., Furtak, K. and Horwich, A. L. “Residues in Chaperonin —GroEL required for polypeptide binding and release” Nature, 1994, 371, 614.
Fersht, A.R.; Itzhaki, L.S.; ElMarsy, N.F.; Matthews, J.M.; Otzen, D.E. “Single Versus Parallel Pathways of Protein-Folding and Fractional Formation of Structure in the Transition-State” Proc. Natl. Acad. Sci, USA, 1994, 91, 10426.
Gervasoni, P., Staudenmann, W., James, P., Genrig, P. and Pluckthun, A. “b-lactamase binds to GroEL in a conformation highly protected against hydrogen /deuterium exchange” Proc. Natl. Acad. Sci.,USA., 1996, 93, 12189.
Goldberg, J.M.; Baldwin, R.L. “Kinetic Mechanism of a Partial Folding Reaction - 2 - Nature of the Transition-State” Biochemisty, 1998, 37, 2556.
Govindarajan, S.; Goldstein, R.A. “Optimal Local Propensities for Model Proteins” Proteins: Struc. Funct. Genet., 1995, 22, 413.
Grantchanova, V., Alm, E. J., Baker, D. and Horwich, A. L. “Mechanisms of Protein Folding” Curr. Opin. Struct. Biol., 2001, 11, 70.
Gross, M., Robinson, C. V., Mayhew, M., Hartl, F. V. and Radford, S. E. “Significant hydrogen exchange protection in GroEL — bound DHFR is maintained during iterative rounds of substrate cycling” Protein Sci., 1996, 5, 2506.
Gross, M., Robinson, C. V., Mayhew, M., Hartl, F. V. and Radford, S. E. “Significant hydrogen exchange protection in GroEL — bound DHFR is maintained during iterative rounds of substrate cycling” Protein Sci., 1996, 5, 2506.
Harrison, S.C.; Durbin, R. “Is There a Single Pathway for the Folding of a Polypeptide-Chain” Proc. Natl. Acad. Sci. USA, 1985 82, 4028.
Hayer-Hartl, M. K., Weber, F. and Hartl, F. U. “Mechanism of Chaperonin action: GroES-binding release can drive GroEL-mediated protein folding in the absence of ATP hydrolysis” EMBO J., 1996, 15, 6111.
Hill, T.L.; “Diffusion frequency factors in some simple examples of transition-state rate theory” Proc. Natl. Acad. Sci., USA, 1976, 73, 679.
Hohfied, J. “Regulation of the heat shock cognate hsc70 in the mammalian cell; the characterization of the anti-apoptic protein BAG-1 provides novel insights” Biol.Chem., 1998, 379, 269.
Horvich, A. “Structural aspects of GroEL function” Curr Opin. Struct. Biol., 1998, 8, 93.
Hunt, J. F., Weaver, A. J., Samuel, J. L., Gierasch, L. and Deisenhofer, J. “The crystal structure of the GroES- Chaperonin at 2.8°A resolution” Nature, 1996, 379, 37.
Ishima, R.; Torchia, D.A. “Protein dynamics from NMR” Nat. Struct. Biol., 2000, 7, 740.
Itzhaki, L.S.; Otzen, D.E.; Fersht, A.R. “Nature and Consequences of GroEL-Protein Interactions” Biochemsitry, 1995, 34, 14581.
Itzhaki, L.S.; Otzen, D.E.; Fersht, A.R. “The Structure of the Transition-State for Folding of Chymotrypsin Inhibitor-2 Analyzed by Protein Engineering Methods - Evidence for a Nucleation-Condensation Mechanism for Protein-Folding” J. Mol. Biol., 1995, 254, 260.
Jackson, S.E.; ElMasry, N.; Fersht, A.R. “Structure of the Hydrophobic Core in the Transition-State for Folding of Chymotrypsin Inhibitor-2 - A Critical Test of the Protein Engineering Method of Analysis” Biochemistry, 1993, 32, 11270.
Kanehisa, M.I.; Tsong, T.Y. “Mechanism of the multiphasic kinetics in the folding and unfolding of globular proteins.” J.Mol.Biol., 1978,124,177.
Kanehisa, M.I.; Tsong, T.Y. “Slow equilibration of a denatured protein: comparison of the cluster model with the proline isomerization model “ J. Mol. Biol., 1979, 133, 279.
Karplus, M.; Weaver, D.L. “Protein-Folding Dynamics - The Diffusion-Collision Model and Experimental-Data” Protein Sci., 1994, 3, 650.
Khorasanizadeh, S.; Peters, I.D.; Roder, H. “Evidence for a 3-State Model of Protein-Folding from Kinetic-Analysis of Ubiquitin Variants with Altered Core Residues” Nat. Struc. Biol., 1996, 3, 193.
Kim, K.S.; Woodward, C. “Hydrogen-exchange identifies native-state motional domains important in protein-folding” Biochemistry, 1993, 32, 9609.
Kim, P.S.; Baldwin, R.L. “Intermediates in the Folding Reactions of Small Proteins” Annu. Rev. Biochem., 1990, 59, 631.
Kim, P.S.; Baldwin, R.L. “Specific Intermediates in the Folding Reactions of Small Proteins and the Mechanism of Protein Folding” Ann. Rev. Biochem., 1982, 51, 459.
Kim, P.S.; Baldwin, R.L. “Specific Intermediates in the Folding Reactions of Small Proteins and the Mechanism of Protein Fold-ing” Annu. Rev. Biochem., 1982, 51, 459.
Klimov, D.K.; Thirumalai, D. “Viscosity Dependence of the Folding Rates of Proteins” Phys. Rev. Lett., 1997, 79, 317.
Lazaridis, T.; Karplus, M. “New View of Protein - Folding Reconciled with the Old Through Multiple Unfolding Simulations” Science, 1997, 278, 1928.
Levinthal, C. “Mössbauer spectroscopy in Biological System” (Bebrunner et al., Eds.), 1969, p22-24.
Li, A.; Dagget, V. “Characterization of the transition state of protein unfolding by use of molecular dynamics: chymotrypsin inhibitor 2” Proc. Natl. Acad. Sci., USA., 1994, 91, 10430.
Li, R.; Woodward, C. Protein Sci., 1999, 8, 1571.
Lin, L.N.; Brandts, J.F. “Further evidence suggesting that the slow phase in protein unfolding and refolding is due to proline isomerization: a kinetic study of carp parvalbumins” Biochemistry, 1978, 17, 4102.
Mach, H.; Middaugh, C.R. “Probing the affinity of polyanions for acidic fibroblast growth factor by unfolding kinetics” Archives of biochemistry and biophysics, 1994, 309, 36.
Mande, S. C., Mehra, V., Bloom, B. R. and Hol, W. G. J. “Structure of the heat shock protein chaperonin —10 of Mycobacterium leprae”. Science, 1996, 271, 203.
Marmorino, J.L.; Lethi, M.; Pielak, G.J. “Native Tertiary Structure in an A-State” J. Mol. Biol., 1998, 275, 379.
Matthews, C.R. “Effect of point mutations on the folding of globular proteins” Methods Enzymol., 1987, 154, 498.
Matthews, C.R. “Pathways of Protein-Folding” Ann. Rev. Biochem., 1993, 62, 653.
Milla, M.E.; Brown, B.M.; Waldburger, C.D.; Saur, R.T. P22 Arc “Repressor — Transition - State Properties Inferred from Mutational Effects on the Rates of Protein Unfolding and Refolding” Biochemistry, 1995, 34, 13914.
Mullins, L.S.; Pace, C.N.; Raushel, F.M. “Investigation of Ribonuclease-T(1) Folding Intermediates by Hydrogen-Deuterium Amide Exchange 2-Dimensional NMR-Spectroscopy” Biochemisty, 1993, 32, 6152.
Nozaki, Y.; Tanford, C. “The solubility of amino acids and two glycine peptides in aqueous ethanol and dioxane solutions. Establishment of a hydrophobicity scale” J. Biol. Chem., 1971, 246, 2211.
Oas, T.G. and Kim, P.S. “A Peptide Model of a Protein Folding Intermediate” Nature, 1988, 336, 42.
Ogural, K.; Nagata, K.; Hatanaka, H.; Habuchi, H.; Kimata, K.; Tate, S.; Ravera, M.W.; Jaye, M.; Schlessinger, J.; Inagaki, F. “Solution structure of human acidic fibroblast growth factor and interaction with heparin-derived hexasaccharide” Journal of biomolecular NMR, 1999, 13, 11.
Ohgushi, M.; Wada, A. “Molten-Globule State - A Compact Form of Globular-Proteins with Mobile Side-Chains” FEBS Lett., 1983, 164, 21.
Oliverberg, M.; Tan, Y.J.; Silow, M.; Fersht, A.R. “The Changing Nature of the Protein-Folding Transition-State - Implications for the Shape of the Free-Energy Profile for Folding” J. Mol. Biol., 1998, 277, 933.
Palmer, A.G. III Curr. Opin. Biotechnol., 1993, 4, 385.
Pande, V.S.; Grosberg, A.Y.; Tanaka, T.; Rokshar, D.S. “Pathways for Protein - Folding - Is a New View Needed” Curr. Opin. Str. Biol., 1998, 8, 68.
Peng, Z.; Kim, P.S. “A protein dissection study of a molten globule” Biochemistry, 1994, 33, 2136
Perrelt, S., Zahn, R., Sternberg, G. and Fersht, A. R. “Importance of electrostatic interactions in the rapid binding of polypeptides to GroEL” J. Mol. Biol., 1997, 269, 892-901.
Ranson, N. A., Dunster, N. J., Burston, S. G. and Clarke, A. R. “Chaperonins can catalyze the reversal of early aggregation steps when a protein misfolds” J. Mol. Biol., 1995, 250, 581.
Robinson, C. V., Gross, M., Eyles, S. J., Ewbank, J., Mayhew, M., Hartl, F. U. and Radford, S. E. “Conformation of GroE-bound alpha-lactalbumin probed by mass spectrometry” Nature, 1994, 372, 646.
Roseman, A. M., Chen, S., White, h., Braig, K., Saibil, H. R. “The chaperonin ATPase cycle mechanism of allsoteric switching and movements of substrate binding domains of GroEL” Cell, 1996, 87, 241.
Samuel, D.; Kumar, T.K.; Srimathi, T.; Hsieh, H.C.; Yu, C. “Identification and Characterization of an Equilibrium Intermediate in the Unfolding Pathway of an All b-Barrel Protein” The Journal of biological chemistry, 2000, 275, 34968.
Sanz, J.M.; GimenezGallego, G. “A partly folded state of acidic fibroblast growth factor at low pH” European Journal of Biochemistry, 1997, 246, 328.
Schiebel, T., Weiki, T. and Buchner, J. “Two chaperone sites in hsp90 differing in substrate specificity and ATP- dependence” Proc. Natl. Acad. Sci., USA., 1998, 95, 1495.
Shortle, D.; Chan, H.S.; Dill, K.A. “Modeling the Effects of Mutations on the Denatured States of Proteins” Protein Sci., 1992,1, 201.
Shrivastava, I.; Visheshwara, S.; Cieplak, M.; Maritan, A.; Banavar, J.R. “Lattice Model for Rapidly Folding Protein-Like Heteropolymers” Proc. Natl. Acad. Sci. USA, 1995, 92, 9206.
Shtilerman, M., Lorimer, G. H. and Englander, S. W. “Chaperonin function folding by forced unfolding” Science, 1999, 284, 822.
Sivaraman, T.; Arrington, C.B. and Robertson, A.D. “Kinetics of unfolding and folding from amide hydrogen exchange in native ubiquitin” Nat. Struct. Biol., 2001, 8, 331.
Sosnick, T.R.; Mayne, L.; Hilter, R.; Englander, S.W. “The Barriers in Protein-Folding” Nat. Struc. Biol., 1994, 1, 149.
Srisailam, S.; Kumar, T.K.; Srimathi, T.; Yu, C. “Influence of backbone conformation on protein aggregation” J Am Chem Soc, 2002, 6, 124, 1884.
Todd, M. J., Viitanen, P. V. and Lorimer, G. H. “Dynamics of the chaperonin ATPase cycle: Implications of facilitated protein folding” Science, 1994, 285, 659.
Tsong, T.Y.; Baldwin, R.L.; Elson, E.L.J. “The sequential unfolding of ribonuclease A: detection of a fast initial phase in the kinetics of unfolding” Proc. Natl. Acad. Sci. USA., 1971, 68, 2712.
Vaguer, A.R.; Martinez, J.C.; Filionov, V.V.; Mateo, R.I.; Serrano, L. “Thermodynamic and Kinetic-Analysis of the Sh3 Domain of Spectrin Shows a 2-State Folding Transition” Biochemistry, 1994, 33, 2142.
Viitanen, P. V., Gatenby, A. A. and Lorimer, G. H. “Purified Chaperonin-60 (GroEL) interacts with the non-native states of a multitude of Escherchia coli proteins” Protein Sci., 1992, 1, 363.
Walter, S., Lorimer, G. H. and Schmid, F. X. “A thermodynamic coupling mechanism for GroEL-mediated unfolding” Procl. Natl. Acad. Sci., USA, 1996, 93, 9425.
Wang, Z, Feng, H., Landry, S. J., Maxwell, J. and Gierasch, L. M. “Basis for substrate binding by the chaperonin GroEL” Biochemistry, 1999, 38, 12537.
Weber, F., Keppel, F., Georgopolous, C., Hayer-Hartl, M.K. and Hartl, F.U “The oligomeric structure of GroEL-GroES is required for biologically significant chaperonin function in protein folding” Nat. Struct, Biol., 1998, 11, 977.
Weissman, J. S., Rye, H. S., Fenton, W. A., Beechem, J. M. and Horwich, A. L. “Characterization of the active intermediate of a GroEL - GroES mediated protein folding reaction” Cell, 1996, 84, 481.
Wetlaufer, D. “Nucleation, rapid folding, and globular intrachain regions in proteins.” Proc. Natl. Acad. Sci., USA., 1973, 94, 697.
Wolynes, P.G. “Folding Funnels and Energy Landscapes of Larger Proteins Within the Capillarity Approximation” Proc. Natl. Acad. Sci., 1997, USA, 94, 6170.
Wu, L.C.; Kim, P.S. “A Specific Hydrophobic Core in the Alpha-Lactalbumin Molten Globule” J. Mol. Biol., 1998, 280, 175.
Xu, Z., Horwich, A. L. and Sigler, P. B. “The crystal structure of the asymmetric GroEL.GroES — ADP97 Chaperonin complex” Nature, 1999, 388, 741.
Zahn, R., Perelt, S. and Fersht, A. R. “Conformational changes bound by the molecular chaperones GroEL and SecB: A hidden Unfolding (Annealing) Activity” J. Mol. Biol., 1996, 251, 43.
Zahn, R., Spitzfaden, C., Ottiger, M., Wuthrich, K. and Pluckthun, A. “Destabilization of the complete secondary structure on binding to the chaperone GroEL” Nature, 1994, 368, 261.