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Ribeiro SS, Castro TG, Gomes CM, Marcos JC. Hofmeister effects on protein stability are dependent on the nature of the unfolded state. Phys Chem Chem Phys 2021; 23:25210-25225. [PMID: 34730580 DOI: 10.1039/d1cp02477a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The interpretation of a salt's effect on protein stability traditionally discriminates low concentration regimes (<0.3 M), dominated by electrostatic forces, and high concentration regimes, generally described by ion-specific Hofmeister effects. However, increased theoretical and experimental studies have highlighted observations of the Hofmeister phenomena at concentration ranges as low as 0.001 M. Reasonable quantitative predictions of such observations have been successfully achieved throughout the inclusion of ion dispersion forces in classical electrostatic theories. This molecular description is also on the basis of quantitative estimates obtained resorting to surface/bulk solvent partition models developed for ion-specific Hofmeister effects. However, the latter are limited by the availability of reliable structures representative of the unfolded state. Here, we use myoglobin as a model to explore how ion-dependency on the nature of the unfolded state affects protein stability, combining spectroscopic techniques with molecular dynamic simulations. To this end, the thermal and chemical stability of myoglobin was assessed in the presence of three different salts (NaCl, (NH4)2SO4 and Na2SO4), at physiologically relevant concentrations (0-0.3 M). We observed mild destabilization of the native state induced by each ion, attributed to unfavorable neutralization and hydrogen-bonding with the protein side-chains. Both effects, combined with binding of Na+, Cl- and SO42- to the thermally unfolded state, resulted in an overall destabilization of the protein. Contrastingly, ion binding was hindered in the chemically unfolded conformation, due to occupation of the binding sites by urea molecules. Such mechanistic action led to a lower degree of destabilization, promoting surface tension effects that stabilized myoglobin according to the Hofmeister series. Therefore, we demonstrate that Hofmeister effects on protein stability are modulated by the heterogeneous physico-chemical nature of the unfolded state. Altogether, our findings evidence the need to characterize the structure of the unfolded state when attempting to dissect the molecular mechanisms underlying the effects of salts on protein stability.
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Affiliation(s)
- Sara S Ribeiro
- Centre of Chemistry, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal.
| | - Tarsila G Castro
- Centre of Biological Engineering, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal
| | - Cláudio M Gomes
- Biosystems and Integrative Sciences Institute, Faculdade de Ciências and Departamento de Química e Bioquímica, Universidade de Lisboa, 1749-016 Lisboa, Portugal
| | - João C Marcos
- Centre of Chemistry, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal.
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Cation Specific Effects on the Domain-Domain Interaction of Heterogeneous Dimeric Protein Revealed by FRET Analysis. J Fluoresc 2020; 30:1121-1129. [PMID: 32648172 DOI: 10.1007/s10895-020-02558-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Accepted: 05/11/2020] [Indexed: 10/23/2022]
Abstract
Specific monovalent cation effects on the domain-domain interaction of heterogeneous dimeric protein were investigated using green fluorescent protein (GFP)-glutathione-s-transferase (GST) fusion protein as a model protein. Conjugating N-terminal of GST domain with a fluorescence probe Cyanine3, complementary increase and decrease of fluorescence intensities of Cyanine3 and GFP were recognized on the exclusive excitation of GFP and further the fluorescence decay of GFP was remarkably accelerated to show that an excellent Förster type of resonance excitation energy transfer (FRET) pair was constructed between GFP- and GST-domain. The spectral overlap integral and critical distance of the FRET pair were estimated to be 5.96×1013 M-1cm3 and 62.5 Å, respectively. The FRET rate and efficiency evaluated by fluorescence lifetime of the energy donor, GFP, were influenced by the monovalent cations included in the buffer solution to suggest that the domain-domain interactions of GFP-GST fusion protein would be susceptible to cation species and their concentrations. The order affecting the domain-domain interaction was estimated to be Li+>NH4+ >Na+>K+>Cs+, almost corresponding to the reverse Hofmeister series.
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Structural changes in halophilic and non-halophilic proteases in response to chaotropic reagents. Protein J 2015; 33:394-402. [PMID: 25008068 DOI: 10.1007/s10930-014-9571-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Halophilic enzymes have been established for their stability and catalytic abilities under harsh operational conditions. These have been documented to withstand denaturation at high temperature, pH, organic solvents, and chaotropic agents. However, this stability is modulated by salt. The present study targets an important aspect in understanding protein-urea/GdmCl interactions using proteases from halophilic Bacillus sp. EMB9 and non-halophilic subtilisin (Carlsberg) from Bacillus licheniformis as model systems. While, halophilic protease containing 1 % (w/v) NaCl (0.17 M) retained full activity towards urea (8 M), non-halophilic protease lost about 90 % activity under similar conditions. The secondary and tertiary structure were lost in non-halophilic but preserved for halophilic protein. This effect could be due to the possible charge screening and shielding of the protein surface by Ca(2+) and Na(+) ions rendering it stable against denaturation. The dialyzed halophilic protease almost behaved like the non-halophilic counterpart. Incorporation of NaCl (up to 5 %, w/v or 0.85 M) in dialyzed EMB9 protease containing urea/GdmCl, not only helped regain of proteolytic activity but also evaded denaturing action. Deciphering the basis of this salt modulated stability amidst a denaturing milieu will provide guidelines and templates for engineering stable proteins/enzymes for biotechnological applications.
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Georgescauld F, Moynié L, Habersetzer J, Cervoni L, Mocan I, Borza T, Harris P, Dautant A, Lascu I. Intersubunit ionic interactions stabilize the nucleoside diphosphate kinase of Mycobacterium tuberculosis. PLoS One 2013; 8:e57867. [PMID: 23526954 PMCID: PMC3589492 DOI: 10.1371/journal.pone.0057867] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2012] [Accepted: 01/27/2013] [Indexed: 01/10/2023] Open
Abstract
Most nucleoside diphosphate kinases (NDPKs) are hexamers. The C-terminal tail interacting with the neighboring subunits is crucial for hexamer stability. In the NDPK from Mycobacterium tuberculosis (Mt) this tail is missing. The quaternary structure of Mt-NDPK is essential for full enzymatic activity and for protein stability to thermal and chemical denaturation. We identified the intersubunit salt bridge Arg80-Asp93 as essential for hexamer stability, compensating for the decreased intersubunit contact area. Breaking the salt bridge by the mutation D93N dramatically decreased protein thermal stability. The mutation also decreased stability to denaturation by urea and guanidinium. The D93N mutant was still hexameric and retained full activity. When exposed to low concentrations of urea it dissociated into folded monomers followed by unfolding while dissociation and unfolding of the wild type simultaneously occur at higher urea concentrations. The dissociation step was not observed in guanidine hydrochloride, suggesting that low concentration of salt may stabilize the hexamer. Indeed, guanidinium and many other salts stabilized the hexamer with a half maximum effect of about 0.1 M, increasing protein thermostability. The crystal structure of the D93N mutant has been solved.
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Affiliation(s)
- Florian Georgescauld
- IBGC, University Bordeaux, Bordeaux, France
- IBGC, CNRS UMR 5095, Bordeaux, France
| | - Lucile Moynié
- IBGC, University Bordeaux, Bordeaux, France
- IBGC, CNRS UMR 5095, Bordeaux, France
| | - Johann Habersetzer
- IBGC, University Bordeaux, Bordeaux, France
- IBGC, CNRS UMR 5095, Bordeaux, France
| | - Laura Cervoni
- Dipartimento di Scienze Biochimiche “A. Rossi Fanelli”, Università degli Studi “La Sapienza”, Roma, Italy
| | - Iulia Mocan
- IBGC, University Bordeaux, Bordeaux, France
- IBGC, CNRS UMR 5095, Bordeaux, France
| | - Tudor Borza
- Laboratoire de Chimie Structurale des Macromolécules, CNRS URA 2185, Institut Pasteur, Paris, France
| | - Pernile Harris
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Alain Dautant
- IBGC, University Bordeaux, Bordeaux, France
- IBGC, CNRS UMR 5095, Bordeaux, France
- * E-mail: (AD); (IL)
| | - Ioan Lascu
- IBGC, University Bordeaux, Bordeaux, France
- IBGC, CNRS UMR 5095, Bordeaux, France
- * E-mail: (AD); (IL)
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Garza-Ramos G, Mújica-Jiménez C, Muñoz-Clares RA. Potassium and ionic strength effects on the conformational and thermal stability of two aldehyde dehydrogenases reveal structural and functional roles of K⁺-binding sites. PLoS One 2013; 8:e54899. [PMID: 23365686 PMCID: PMC3554688 DOI: 10.1371/journal.pone.0054899] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2012] [Accepted: 12/17/2012] [Indexed: 11/18/2022] Open
Abstract
Many aldehyde dehydrogenases (ALDHs) have potential potassium-binding sites of as yet unknown structural or functional roles. To explore possible K(+)-specific effects, we performed comparative structural studies on the tetrameric betaine aldehyde dehydrogenase from Pseudomonas aeruginosa (PaBADH) and on the dimeric BADH from spinach (SoBADH), whose activities are K(+)-dependent and K(+)-independent, respectively, although both enzymes contain potassium-binding sites. Size exclusion chromatography, dynamic light scattering, far- and near-UV circular dichroism, and extrinsic fluorescence results indicated that in the absence of K(+) ions and at very low ionic strength, PaBADH remained tetrameric but its tertiary structure was significantly altered, accounting for its inactivation, whereas SoBADH formed tetramers that maintained the native tertiary structure. The recovery of PaBADH native tertiary-structure was hyperbolically dependent on KCl concentration, indicating potassium-specific structuring effects probably arising from binding to a central-cavity site present in PaBADH but not in SoBADH. K(+) ions stabilized the native structure of both enzymes against thermal denaturation more than did tetraethylammonium (TEA(+)) ions. This indicated specific effects of potassium on both enzymes, particularly on PaBADH whose apparent T(m) values showed hyperbolical dependence on potassium concentration, similar to that observed with the tertiary structure changes. Interestingly, we also found that thermal denaturation of both enzymes performed in low ionic-strength buffers led to formation of heat-resistant, inactive soluble aggregates that retain 80% secondary structure, have increased β-sheet content and bind thioflavin T. These structured aggregates underwent further thermal-induced aggregation and precipitation when the concentrations of KCl or TEACl were raised. Given that PaBADH and SoBADH belong to different ALDH families and differ not only in amino acid composition but also in association state and surface electrostatic potential, the formation of this kind of β-sheet pre-fibrillar aggregates, not described before for any ALDH enzyme, appear to be a property of the ALDH fold.
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Affiliation(s)
- Georgina Garza-Ramos
- Departamento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México, México, Distrito Federal, México
| | - Carlos Mújica-Jiménez
- Departamento de Bioquímica, Facultad de Química, Universidad Nacional Autónoma de México, México, Distrito Federal, México
| | - Rosario A. Muñoz-Clares
- Departamento de Bioquímica, Facultad de Química, Universidad Nacional Autónoma de México, México, Distrito Federal, México
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Ion specific influences on the stability and unfolding transitions of a naturally aggregating protein; RecA. Biophys Chem 2012; 163-164:56-63. [DOI: 10.1016/j.bpc.2012.02.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2012] [Revised: 02/13/2012] [Accepted: 02/18/2012] [Indexed: 10/28/2022]
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Wang Q, Christiansen A, Samiotakis A, Wittung-Stafshede P, Cheung MS. Comparison of chemical and thermal protein denaturation by combination of computational and experimental approaches. II. J Chem Phys 2012; 135:175102. [PMID: 22070324 DOI: 10.1063/1.3656692] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Chemical and thermal denaturation methods have been widely used to investigate folding processes of proteins in vitro. However, a molecular understanding of the relationship between these two perturbation methods is lacking. Here, we combined computational and experimental approaches to investigate denaturing effects on three structurally different proteins. We derived a linear relationship between thermal denaturation at temperature T(b) and chemical denaturation at another temperature T(u) using the stability change of a protein (ΔG). For this, we related the dependence of ΔG on temperature, in the Gibbs-Helmholtz equation, to that of ΔG on urea concentration in the linear extrapolation method, assuming that there is a temperature pair from the urea (T(u)) and the aqueous (T(b)) ensembles that produces the same protein structures. We tested this relationship on apoazurin, cytochrome c, and apoflavodoxin using coarse-grained molecular simulations. We found a linear correlation between the temperature for a particular structural ensemble in the absence of urea, T(b), and the temperature of the same structural ensemble at a specific urea concentration, T(u). The in silico results agreed with in vitro far-UV circular dichroism data on apoazurin and cytochrome c. We conclude that chemical and thermal unfolding processes correlate in terms of thermodynamics and structural ensembles at most conditions; however, deviations were found at high concentrations of denaturant.
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Affiliation(s)
- Qian Wang
- Department of Physics, University of Houston, Houston, Texas 77204-5005, USA
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Karan R, Capes MD, DasSarma S. Function and biotechnology of extremophilic enzymes in low water activity. AQUATIC BIOSYSTEMS 2012; 8:4. [PMID: 22480329 PMCID: PMC3310334 DOI: 10.1186/2046-9063-8-4] [Citation(s) in RCA: 128] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/14/2011] [Accepted: 02/02/2012] [Indexed: 05/31/2023]
Abstract
Enzymes from extremophilic microorganisms usually catalyze chemical reactions in non-standard conditions. Such conditions promote aggregation, precipitation, and denaturation, reducing the activity of most non-extremophilic enzymes, frequently due to the absence of sufficient hydration. Some extremophilic enzymes maintain a tight hydration shell and remain active in solution even when liquid water is limiting, e.g. in the presence of high ionic concentrations, or at cold temperature when water is close to the freezing point. Extremophilic enzymes are able to compete for hydration via alterations especially to their surface through greater surface charges and increased molecular motion. These properties have enabled some extremophilic enzymes to function in the presence of non-aqueous organic solvents, with potential for design of useful catalysts. In this review, we summarize the current state of knowledge of extremophilic enzymes functioning in high salinity and cold temperatures, focusing on their strategy for function at low water activity. We discuss how the understanding of extremophilic enzyme function is leading to the design of a new generation of enzyme catalysts and their applications to biotechnology.
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Affiliation(s)
- Ram Karan
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD, USA
- Institute of Marine and Environmental Technology, University System of Maryland, Baltimore, MD, USA
| | - Melinda D Capes
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD, USA
- Institute of Marine and Environmental Technology, University System of Maryland, Baltimore, MD, USA
| | - Shiladitya DasSarma
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD, USA
- Institute of Marine and Environmental Technology, University System of Maryland, Baltimore, MD, USA
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Zavitsas A. The Nature of Aqueous Solutions: Insights into Multiple Facets of Chemistry and Biochemistry from Freezing-Point Depressions. Chemistry 2010; 16:5942-60. [DOI: 10.1002/chem.200903063] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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11
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Bončina M, Lah J, Reščič J, Vlachy V. Thermodynamics of the Lysozyme−Salt Interaction from Calorimetric Titrations. J Phys Chem B 2010; 114:4313-9. [DOI: 10.1021/jp9071845] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Matjaž Bončina
- Faculty of Chemistry and Chemical Technology, University of Ljubljana, SI-1000 Ljubljana, Slovenia
| | - Jurij Lah
- Faculty of Chemistry and Chemical Technology, University of Ljubljana, SI-1000 Ljubljana, Slovenia
| | - Jurij Reščič
- Faculty of Chemistry and Chemical Technology, University of Ljubljana, SI-1000 Ljubljana, Slovenia
| | - Vojko Vlachy
- Faculty of Chemistry and Chemical Technology, University of Ljubljana, SI-1000 Ljubljana, Slovenia
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12
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Zavitsas AA. Ideal Behavior of Water Solutions of Strong Electrolytes and Non-electrolytes at High Concentrations. J SOLUTION CHEM 2010. [DOI: 10.1007/s10953-010-9503-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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13
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Fu H, Hong X, Wan A, Batteas JD, Bergbreiter DE. Parallel effects of cations on PNIPAM graft wettability and PNIPAM solubility. ACS APPLIED MATERIALS & INTERFACES 2010; 2:452-458. [PMID: 20356191 DOI: 10.1021/am9007006] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Stimuli-responsive surfaces grafted with thermoresponsive polymers switch from hydrophilic to hydrophobic thermally, making these surfaces attractive in applications such as in microfluidics devices, as antifouling surfaces, and in cell culture and tissue engineering. These materials exhibit changes in wettability as the polymer undergoes a phase transition above its lower critical solution temperature (LCST). Because the presence of salts affects LCSTs in accordance to the Hofmeister series, salt effects on the wettability of these thermoresponsive surfaces will dramatically impact device performance. Prior studies of such effects have focused on the influence of anions. Detailed studies of the effects of cations have not been carried out. Here, the influence of varying cation identity in a series of mono-, di-, and trivalent sulfate salts on the wettability of a stimuli-responsive grafted surface was investigated by measuring advancing water contact angle (Theta(a)) changes. The cation-induced changes in Theta(a) were correlated with corresponding changes in surface morphology examined by AFM. The results showed that the effects of varying cations on surface wettability are as large as the effects of varying anion identity and concentration (i.e., Theta(a) changes of up to 90 degrees). Parallel studies of the effects of varying the cation identity and concentration for these same cation sulfate salts in solution show that cation variation also has a large effect on the LCST of PNIPAM, the stimuli responsive polymer component of the nanocomposite grafts that were studied. Moreover, analyses of the Theta(a) and LCST data using activity showed that the Theta(a) or LCST versus cation activity/concentration could be readily grouped by charge. Such differences are not seen in similar studies where anion identity, charge, and concentration are changed.
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Affiliation(s)
- Hui Fu
- Department of Chemistry, Texas A&M University, College Station, TX 77842-3012, USA
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Stagg L, Samiotakis A, Homouz D, Cheung MS, Wittung-Stafshede P. Residue-specific analysis of frustration in the folding landscape of repeat beta/alpha protein apoflavodoxin. J Mol Biol 2009; 396:75-89. [PMID: 19913555 DOI: 10.1016/j.jmb.2009.11.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2009] [Revised: 11/04/2009] [Accepted: 11/05/2009] [Indexed: 11/17/2022]
Abstract
Flavodoxin adopts the common repeat beta/alpha topology and folds in a complex kinetic reaction with intermediates. To better understand this reaction, we analyzed a set of Desulfovibrio desulfuricans apoflavodoxin variants with point mutations in most secondary structure elements by in vitro and in silico methods. By equilibrium unfolding experiments, we first revealed how different secondary structure elements contribute to overall protein resistance to heat and urea. Next, using stopped-flow mixing coupled with far-UV circular dichroism, we probed how individual residues affect the amount of structure formed in the experimentally detected burst-phase intermediate. Together with in silico folding route analysis of the same point-mutated variants and computation of growth in nucleation size during early folding, computer simulations suggested the presence of two competing folding nuclei at opposite sides of the central beta-strand 3 (i.e., at beta-strands 1 and 4), which cause early topological frustration (i.e., misfolding) in the folding landscape. Particularly, the extent of heterogeneity in folding nuclei growth correlates with the in vitro burst-phase circular dichroism amplitude. In addition, phi-value analysis (in vitro and in silico) of the overall folding barrier to apoflavodoxin's native state revealed that native-like interactions in most of the beta-strands must form in transition state. Our study reveals that an imbalanced competition between the two sides of apoflavodoxin's central beta-sheet directs initial misfolding, while proper alignment on both sides of beta-strand 3 is necessary for productive folding.
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Affiliation(s)
- Loren Stagg
- Department of Biochemistry and Cell Biology, Rice University, Houston, TX 77251, USA
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15
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Varhač R, Tomášková N, Fabián M, Sedlák E. Kinetics of cyanide binding as a probe of local stability/flexibility of cytochrome c. Biophys Chem 2009; 144:21-6. [DOI: 10.1016/j.bpc.2009.06.001] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2009] [Revised: 05/30/2009] [Accepted: 06/01/2009] [Indexed: 10/20/2022]
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16
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Jorgensen L, Hostrup S, Moeller EH, Grohganz H. Recent trends in stabilising peptides and proteins in pharmaceutical formulation – considerations in the choice of excipients. Expert Opin Drug Deliv 2009; 6:1219-30. [DOI: 10.1517/17425240903199143] [Citation(s) in RCA: 94] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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17
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Effect of Hofmeister ions on protein thermal stability: Roles of ion hydration and peptide groups? Arch Biochem Biophys 2008; 479:69-73. [DOI: 10.1016/j.abb.2008.08.013] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2008] [Revised: 08/17/2008] [Accepted: 08/20/2008] [Indexed: 11/22/2022]
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