1
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Chura-Chambi RM, Farah CS, Morganti L. Human growth hormone inclusion bodies present native-like secondary and tertiary structures which can be preserved by mild solubilization for refolding. Microb Cell Fact 2022; 21:164. [PMID: 35978337 PMCID: PMC9382763 DOI: 10.1186/s12934-022-01887-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Accepted: 08/02/2022] [Indexed: 11/22/2022] Open
Abstract
BACKGROUND Native-like secondary structures and biological activity have been described for proteins in inclusion bodies (IBs). Tertiary structure analysis, however, is hampered due to the necessity of mild solubilization conditions. Denaturing reagents used for IBs solubilization generally lead to the loss of these structures and to consequent reaggregation due to intermolecular interactions among exposed hydrophobic domains after removal of the solubilization reagent. The use of mild, non-denaturing solubilization processes that maintain existing structures could allow tertiary structure analysis and increase the efficiency of refolding. RESULTS In this study we use a variety of biophysical methods to analyze protein structure in human growth hormone IBs (hGH-IBs). hGH-IBs present native-like secondary and tertiary structures, as shown by far and near-UV CD analysis. hGH-IBs present similar λmax intrinsic Trp fluorescence to the native protein (334 nm), indicative of a native-like tertiary structure. Similar fluorescence behavior was also obtained for hGH solubilized from IBs and native hGH at pH 10.0 and 2.5 kbar and after decompression. hGH-IBs expressed in E. coli were extracted to high yield and purity (95%) and solubilized using non-denaturing conditions [2.4 kbar, 0.25 M arginine (pH 10), 10 mM DTT]. After decompression, the protein was incubated at pH 7.4 in the presence of the glutathione-oxidized glutathione (GSH-GSSG) pair which led to intramolecular disulfide bond formation and refolded hGH (81% yield). CONCLUSIONS We have shown that hGH-IBs present native-like secondary and tertiary structures and that non-denaturing methods that aim to preserve them can lead to high yields of refolded protein. It is likely that the refolding process described can be extended to different proteins and may be particularly useful to reduce the pH required for alkaline solubilization.
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Affiliation(s)
- Rosa Maria Chura-Chambi
- Centro de Biotecnologia, Instituto de Pesquisas Energéticas e Nucleares, IPEN-CNEN/SP, São Paulo, SP, Brazil
| | - Chuck Shaker Farah
- Departamento de Bioquímica, Instituto de Química da Universidade de São Paulo, São Paulo, SP, Brazil
| | - Ligia Morganti
- Centro de Biotecnologia, Instituto de Pesquisas Energéticas e Nucleares, IPEN-CNEN/SP, São Paulo, SP, Brazil.
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2
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Groves K, Ashcroft AE, Cryar A, Sula A, Wallace BA, Stocks BB, Burns C, Cooper-Shepherd D, De Lorenzi E, Rodriguez E, Zhang H, Ault JR, Ferguson J, Phillips JJ, Pacholarz K, Thalassinos K, Luckau L, Ashton L, Durrant O, Barran P, Dalby P, Vicedo P, Colombo R, Davis R, Parakra R, Upton R, Hill S, Wood V, Soloviev Z, Quaglia M. Reference Protocol to Assess Analytical Performance of Higher Order Structural Analysis Measurements: Results from an Interlaboratory Comparison. Anal Chem 2021; 93:9041-9048. [PMID: 34165299 DOI: 10.1021/acs.analchem.0c04625] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Measurements of protein higher order structure (HOS) provide important information on stability, potency, efficacy, immunogenicity, and biosimilarity of biopharmaceuticals, with a significant number of techniques and methods available to perform these measurements. The comparison of the analytical performance of HOS methods and the standardization of the results is, however, not a trivial task, due to the lack of reference protocols and reference measurement procedures. Here, we developed a protocol to structurally alter and compare samples of somatropin, a recombinant biotherapeutic, and describe the results obtained by using a number of techniques, methods and in different laboratories. This, with the final aim to provide tools and generate a pool of data to compare and benchmark analytical platforms and define method sensitivity to structural changes. Changes in somatropin HOS, induced by the presence of zinc at increasing concentrations, were observed, both globally and at more localized resolution, across many of the methods utilized in this study and with different sensitivities, suggesting the suitability of the protocol to improve understanding of inter- and cross-platform measurement comparability and assess analytical performance as appropriate.
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Affiliation(s)
- K Groves
- National Measurement Laboratory, LGC Ltd. Queens Road, Teddington, Middlesex TW11 0LY, U.K
| | - A E Ashcroft
- Astbury Centre for Structural Molecular Biology & School of Molecular and Cellular Biology, University of Leeds, Leeds LS2 9JT, U.K
| | - A Cryar
- National Measurement Laboratory, LGC Ltd. Queens Road, Teddington, Middlesex TW11 0LY, U.K
| | - A Sula
- Institute of Structural and Molecular Biology, Birkbeck College, University of London, London WC1E 7HX, U.K
| | - B A Wallace
- Institute of Structural and Molecular Biology, Birkbeck College, University of London, London WC1E 7HX, U.K
| | - B B Stocks
- National Research Council Canada, 1200 Montreal Road, Ottawa K1A 0R6, Canada
| | - C Burns
- Biotherapeutics Division, National Institute for Biological Standards and Control, Blanche Lane South Mimms, Potters Bar, Hertfordshire EN6 3QG, U.K
| | - D Cooper-Shepherd
- National Measurement Laboratory, LGC Ltd. Queens Road, Teddington, Middlesex TW11 0LY, U.K
| | - E De Lorenzi
- Department of Drug Sciences, University of Pavia, Viale Taramelli 12, 27100 Pavia, Italy
| | - E Rodriguez
- UCB Celltech, 216 Bath Road, Slough, Berkshire SL1 3WE, U.K
| | - H Zhang
- Department of Biochemical Engineering, University College London, London WC1E 6BT, U.K
| | - J R Ault
- Astbury Centre for Structural Molecular Biology & School of Molecular and Cellular Biology, University of Leeds, Leeds LS2 9JT, U.K
| | - J Ferguson
- Biotherapeutics Division, National Institute for Biological Standards and Control, Blanche Lane South Mimms, Potters Bar, Hertfordshire EN6 3QG, U.K
| | - J J Phillips
- Living Systems Institute, Department of Biosciences, University of Exeter, Exeter EX4 4QD, , U.K
| | - K Pacholarz
- Manchester Institute of Biotechnology, The University of Manchester, 131 Princess Street, Manchester M1 7DN, U.K
| | - K Thalassinos
- Institute of Structural and Molecular Biology, Division of Biosciences, University College London, London WC1E 6AR, U.K
| | - L Luckau
- National Measurement Laboratory, LGC Ltd. Queens Road, Teddington, Middlesex TW11 0LY, U.K
| | - L Ashton
- Department of Chemistry, Lancaster University, Lancaster LA1 4YB, U.K
| | - O Durrant
- UCB Celltech, 216 Bath Road, Slough, Berkshire SL1 3WE, U.K
| | - P Barran
- Manchester Institute of Biotechnology, The University of Manchester, 131 Princess Street, Manchester M1 7DN, U.K
| | - P Dalby
- Department of Biochemical Engineering, University College London, London WC1E 6BT, U.K
| | - P Vicedo
- Manchester Institute of Biotechnology, The University of Manchester, 131 Princess Street, Manchester M1 7DN, U.K
| | - R Colombo
- Department of Drug Sciences, University of Pavia, Viale Taramelli 12, 27100 Pavia, Italy
| | - R Davis
- UCB Celltech, 216 Bath Road, Slough, Berkshire SL1 3WE, U.K
| | - R Parakra
- Living Systems Institute, Department of Biosciences, University of Exeter, Exeter EX4 4QD, , U.K
| | - R Upton
- Manchester Institute of Biotechnology, The University of Manchester, 131 Princess Street, Manchester M1 7DN, U.K
| | - S Hill
- National Measurement Laboratory, LGC Ltd. Queens Road, Teddington, Middlesex TW11 0LY, U.K
| | - V Wood
- Department of Biochemical Engineering, University College London, London WC1E 6BT, U.K
| | - Z Soloviev
- Institute of Structural and Molecular Biology, Division of Biosciences, University College London, London WC1E 6AR, U.K
| | - M Quaglia
- National Measurement Laboratory, LGC Ltd. Queens Road, Teddington, Middlesex TW11 0LY, U.K
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3
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Sanchez-Fernandez A, Diehl C, Houston JE, Leung AE, Tellam JP, Rogers SE, Prevost S, Ulvenlund S, Sjögren H, Wahlgren M. An integrative toolbox to unlock the structure and dynamics of protein-surfactant complexes. NANOSCALE ADVANCES 2020; 2:4011-4023. [PMID: 36132802 PMCID: PMC9417085 DOI: 10.1039/d0na00194e] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2020] [Accepted: 07/11/2020] [Indexed: 05/06/2023]
Abstract
The interactions between protein and surfactants play an important role in the stability and performance of formulated products. Due to the high complexity of such interactions, multi-technique approaches are required to study these systems. Here, an integrative approach is used to investigate the various interactions in a model system composed of human growth hormone and sodium dodecyl sulfate. Contrast variation small-angle neutron scattering was used to obtain information on the structure of the protein, surfactant aggregates and surfactant-protein complexes. 1H and 1H-13C HSQC nuclear magnetic resonance spectroscopy was employed to probe the local structure and dynamics of specific amino acids upon surfactant addition. Through the combination of these advanced methods with fluorescence spectroscopy, circular dichroism and isothermal titration calorimetry, it was possible to identify the interaction mechanisms between the surfactant and the protein in the pre- and post-micellar regimes, and interconnect the results from different techniques. As such, the protein was revealed to evolve from a partially unfolded conformation at low SDS concentration to a molten globule at intermediate concentrations, where the protein conformation and local dynamics of hydrophobic amino acids are partially affected compared to the native state. At higher surfactant concentrations the local structure of the protein appears disrupted, and a decorated micelle structure is observed, where the protein is wrapped around a surfactant assembly. Importantly, this integrative approach allows for the identification of the characteristic fingerprints of complex transitions as seen by each technique, and establishes a methodology for an in-detail study of surfactant-protein systems.
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Affiliation(s)
| | - Carl Diehl
- SARomics Biostructures AB Medicon Village, Scheelevägen 2 223 81 Lund Sweden
| | | | - Anna E Leung
- European Spallation Source Box 176 221 00 Lund Sweden
| | - James P Tellam
- ISIS Neutron and Muon Source, Science and Technology Facilities Council, Rutherford Appleton Laboratory Didcot OX11 0QX UK
| | - Sarah E Rogers
- ISIS Neutron and Muon Source, Science and Technology Facilities Council, Rutherford Appleton Laboratory Didcot OX11 0QX UK
| | - Sylvain Prevost
- Institut Laue-Langevin 71 Avenue des Martyrs 38000 Grenoble France
| | - Stefan Ulvenlund
- Food Technology, Engineering and Nutrition, Lund University Box 124 221 00 Lund Sweden
- EnzaBiotech AB Scheelevägen 22 223 63 Lund Sweden
| | - Helen Sjögren
- Ferring Pharmaceuticals A/S Kay Fiskers Plads 11 2300 Copenhagen S Denmark
| | - Marie Wahlgren
- Food Technology, Engineering and Nutrition, Lund University Box 124 221 00 Lund Sweden
- EnzaBiotech AB Scheelevägen 22 223 63 Lund Sweden
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4
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Smith LJ, Athill R, van Gunsteren WF, Hansen N. Interpretation of Seemingly Contradictory Data: Low NMR S 2 Order Parameters Observed in Helices and High NMR S 2 Order Parameters in Disordered Loops of the Protein hGH at Low pH. Chemistry 2017; 23:9585-9591. [PMID: 28503764 DOI: 10.1002/chem.201700896] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Indexed: 12/16/2022]
Abstract
At low pH, human growth hormone (hGH) adopts a partially folded state, in which the native helices are maintained, but the long loop regions and side-chain packing become disordered. Some of the S2 order parameters for backbone N-H vectors derived from NMR relaxation measurements on hGH at low pH initially seem contradictory. Three isolated residues (15, 20, and 171) in helices A and D exhibit low order parameter values (<0.5) indicating flexibility, whereas residue 143 in the centre of a long flexible loop region has a high order parameter (0.82). Using S2 order parameter restraining MD simulations, this paradox has been resolved. Low S2 values in helices are due to the presence of a mixture of 310 -helical and α-helical hydrogen bonds. High S2 values in relatively disordered parts of a protein may be due to fluctuating networks of hydrogen bonds between the backbone and the side chains, which restrict the motion of N-H bond vectors.
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Affiliation(s)
- Lorna J Smith
- Department of Chemistry, University of Oxford, Inorganic Chemistry Laboratory, South Parks Road, Oxford, OX1 3QR, UK
| | - Roya Athill
- Department of Chemistry, University of Oxford, Inorganic Chemistry Laboratory, South Parks Road, Oxford, OX1 3QR, UK
| | | | - Niels Hansen
- Institute of Thermodynamics and Thermal Process Engineering, University of Stuttgart, 70569, Stuttgart, Germany
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5
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The Study of the Concentration Increasing Effect in the Combination of Zinc Ion with Human Growth Hormone by Molecular Dynamics Simulation. IRANIAN JOURNAL OF SCIENCE AND TECHNOLOGY, TRANSACTIONS A: SCIENCE 2017. [DOI: 10.1007/s40995-016-0026-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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6
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Borotto NB, Zhou Y, Hollingsworth SR, Hale JE, Graban EM, Vaughan RC, Vachet RW. Investigating Therapeutic Protein Structure with Diethylpyrocarbonate Labeling and Mass Spectrometry. Anal Chem 2015; 87:10627-34. [PMID: 26399599 DOI: 10.1021/acs.analchem.5b03180] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Protein therapeutics are rapidly transforming the pharmaceutical industry. Unlike for small molecule therapeutics, current technologies are challenged to provide the rapid, high-resolution analyses of protein higher order structures needed to ensure drug efficacy and safety. Consequently, significant attention has turned to developing new methods that can quickly, accurately, and reproducibly characterize the three-dimensional structure of protein therapeutics. In this work, we describe a method that uses diethylpyrocarbonate (DEPC) labeling and mass spectrometry to detect three-dimensional structural changes in therapeutic proteins that have been exposed to degrading conditions. Using β2-microglobulin, immunoglobulin G1, and human growth hormone as model systems, we demonstrate that DEPC labeling can identify both specific protein regions that mediate aggregation and those regions that undergo more subtle structural changes upon mishandling of these proteins. Importantly, DEPC labeling is able to provide information for up to 30% of the surface residues in a given protein, thereby providing excellent structural resolution. Given the simplicity of the DEPC labeling chemistry and the relatively straightforward mass spectral analysis of DEPC-labeled proteins, we expect this method should be amenable to a wide range of protein therapeutics and their different formulations.
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Affiliation(s)
- Nicholas B Borotto
- Department of Chemistry, University of Massachusetts , Amherst, Massachusetts 01003, United States
| | - Yuping Zhou
- Department of Chemistry, University of Massachusetts , Amherst, Massachusetts 01003, United States
| | - Stephen R Hollingsworth
- Department of Molecular and Cellular Biochemistry, Indiana University , Bloomington, Indiana 47405, United States
| | - John E Hale
- QuarryBio , Bloomington, Indiana 47404, United States
| | - Eric M Graban
- QuarryBio , Bloomington, Indiana 47404, United States
| | - Robert C Vaughan
- Department of Molecular and Cellular Biochemistry, Indiana University , Bloomington, Indiana 47405, United States
| | - Richard W Vachet
- Department of Chemistry, University of Massachusetts , Amherst, Massachusetts 01003, United States
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7
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Johansson H, Jensen MR, Gesmar H, Meier S, Vinther JM, Keeler C, Hodsdon ME, Led JJ. Specific and nonspecific interactions in ultraweak protein-protein associations revealed by solvent paramagnetic relaxation enhancements. J Am Chem Soc 2014; 136:10277-86. [PMID: 24969589 PMCID: PMC4111215 DOI: 10.1021/ja503546j] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
![]()
Weak
and transient protein–protein interactions underlie
numerous biological processes. However, the location of the interaction
sites of the specific complexes and the effect of transient, nonspecific
protein–protein interactions often remain elusive. We have
investigated the weak self-association of human growth hormone (hGH, KD = 0.90 ± 0.03 mM) at neutral pH by the
paramagnetic relaxation enhancement (PRE) of the amide protons induced
by the soluble paramagnetic relaxation agent, gadodiamide (Gd(DTPA-BMA)).
Primarily, it was found that the PREs are in agreement with the general
Hwang-Freed model for relaxation by translational diffusion (J. Chem. Phys.1975, 63, 4017–4025),
only if crowding effects on the diffusion in the protein solution
are taken into account. Second, by measuring the PREs of the amide
protons at increasing hGH concentrations and a constant concentration
of the relaxation agent, it is shown that a distinction can be made
between residues that are affected only by transient, nonspecific
protein–protein interactions and residues that are involved
in specific protein–protein associations. Thus, the PREs of
the former residues increase linearly with the hGH concentration in
the entire concentration range because of a reduction of the diffusion
caused by the transient, nonspecific protein–protein interactions,
while the PREs of the latter residues increase only at the lower hGH
concentrations but decrease at the higher concentrations because of
specific protein–protein associations that impede the access
of gadodiamide to the residues of the interaction surface. Finally,
it is found that the ultraweak aggregation of hGH involves several
interaction sites that are located in patches covering a large part
of the protein surface.
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Affiliation(s)
- Helle Johansson
- Department of Chemistry, University of Copenhagen , Universitetsparken 5, DK-2100 Copenhagen Ø, Denmark
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8
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Prokaryotic soluble overexpression and purification of bioactive human growth hormone by fusion to thioredoxin, maltose binding protein, and protein disulfide isomerase. PLoS One 2014; 9:e89038. [PMID: 24614134 PMCID: PMC3948679 DOI: 10.1371/journal.pone.0089038] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2013] [Accepted: 01/14/2014] [Indexed: 11/25/2022] Open
Abstract
Human growth hormone (hGH) is synthesized by somatotroph cells of the anterior pituitary gland and induces cell proliferation and growth. This protein has been approved for the treatment of various conditions, including hGH deficiency, chronic renal failure, and Turner syndrome. Efficient production of hGH in Escherichia coli (E. coli) has proven difficult because the E. coli-expressed hormone tends to aggregate and form inclusion bodies, resulting in poor solubility. In this study, seven N-terminal fusion partners, hexahistidine (His6), thioredoxin (Trx), glutathione S-transferase (GST), maltose-binding protein (MBP), N-utilization substance protein A (NusA), protein disulfide bond isomerase (PDI), and the b′a′ domain of PDI (PDIb′a′), were tested for soluble overexpression of codon-optimized hGH in E. coli. We found that MBP and hPDI tags significantly increased the solubility of the hormone. In addition, lowering the expression temperature to 18°C also dramatically increased the solubility of all the fusion proteins. We purified hGH from MBP-, PDIb′a′-, or Trx-tagged hGH expressed at 18°C in E. coli using simple chromatographic techniques and compared the final purity, yield, and activity of hGH to assess the impact of each partner protein. Purified hGH was highly pure on silver-stained gel and contained very low levels of endotoxin. On average, ∼37 mg, ∼12 mg, and ∼7 mg of hGH were obtained from 500 mL-cell cultures of Trx-hGH, MBP-hGH, and PDIb′a′-hGH, respectively. Subsequently, hGH was analyzed using mass spectroscopy to confirm the presence of two intra-molecular disulfide bonds. The bioactivity of purified hGHs was demonstrated using Nb2-11 cell.
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9
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Mulinacci F, Poirier E, Capelle MA, Gurny R, Arvinte T. Influence of methionine oxidation on the aggregation of recombinant human growth hormone. Eur J Pharm Biopharm 2013; 85:42-52. [DOI: 10.1016/j.ejpb.2013.03.015] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2012] [Revised: 03/14/2013] [Accepted: 03/19/2013] [Indexed: 10/26/2022]
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10
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Pritchard C, O’Connor G, Ashcroft AE. The Role of Ion Mobility Spectrometry–Mass Spectrometry in the Analysis of Protein Reference Standards. Anal Chem 2013; 85:7205-12. [DOI: 10.1021/ac400927s] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Affiliation(s)
- Caroline Pritchard
- Astbury Centre for Structural
Molecular Biology, University of Leeds,
Leeds LS2 9JT, United Kingdom
- LGC, Queens Road, Teddington TW11 0LY,
United Kingdom
| | | | - Alison E. Ashcroft
- Astbury Centre for Structural
Molecular Biology, University of Leeds,
Leeds LS2 9JT, United Kingdom
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11
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Mulinacci F, Capelle MA, Gurny R, Drake AF, Arvinte T. Stability of Human Growth Hormone: Influence of Methionine Oxidation on Thermal Folding. J Pharm Sci 2011; 100:451-63. [DOI: 10.1002/jps.22293] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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12
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Coales SJ, E SY, Lee JE, Ma A, Morrow JA, Hamuro Y. Expansion of time window for mass spectrometric measurement of amide hydrogen/deuterium exchange reactions. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2010; 24:3585-3592. [PMID: 21108306 DOI: 10.1002/rcm.4814] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Backbone amide hydrogen exchange rates can be used to describe the dynamic properties of a protein. Amide hydrogen exchange rates in a native protein may vary from milliseconds (ms) to several years. Ideally, the rates of all amide hydrogens of the analyte protein can be determined individually. To achieve this goal, monitoring of a wider time window is critical, in addition to high sequence coverage and high sequence resolution. Significant improvements have been made to hydrogen/deuterium exchange mass spectrometry methods in the past decade for better sequence coverage and higher sequence resolution. On the other hand, little effort has been made to expand the experimental time window to accurately determine exchange rates of amide hydrogens. Many fast exchanging amide hydrogens are completely exchanged before completion of a typical short exchange time point (10-30 s) and many slow exchanging amide hydrogens do not start exchanging before a typical long exchanging time point (1-3 h). Here various experimental conditions, as well as a quenched-flow apparatus, are utilized to monitor cytochrome c amide hydrogen exchange behaviors over more than eight orders of magnitude (0.0044-1 000 000 s), when converted into the standard exchange condition (pH 7 and 23°C).
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Affiliation(s)
- Stephen J Coales
- ExSAR Corporation, 11 Deer Park Drive, Suite 103, Monmouth Junction, NJ 08852, USA
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13
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Vinther JM, Kristensen SM, Led JJ. Enhanced stability of a protein with increasing temperature. J Am Chem Soc 2010; 133:271-8. [PMID: 21166411 DOI: 10.1021/ja105388k] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The unusual stability of a structured but locally flexible protein, human growth hormone (hGH) at pH 2.7, was investigated using the temperature dependence of the nanosecond-picosecond dynamics of the backbone amide groups obtained from (15)N NMR relaxation data. It is found that the flexibility of the backbone of the helices decreases with temperature in the range from 24 °C to ∼40 °C, corresponding to an increasing stability. A concomitant increase with temperature of the electrostatic interactions between charged residues forming an interhelical network of salt bridges at the center of the four-helix core suggests that these interactions give rise to the decreasing flexibility and increasing stability of the protein. However, numerous hydrophobic interactions in the interior of the four-helix core may also contribute. Above ∼40 °C, where the thermal energy overcomes the electrostatic and hydrophobic interactions, a substantial increase in the flexibility of the helix backbones results in a highly positive contribution from the local conformational heat capacity, C(p, conf), of the helix backbones to the total heat capacity, C(p), of the protein. This reduces the change in heat capacity upon unfolding, ΔC(p), increases the change in the Gibbs free energy, ΔG(unfold), and stabilizes the protein at high temperatures. A similar decrease in flexibility is found near other salt bridges in hGH and in Calmodulin and may be of general importance for the thermostability of proteins and, in particular, of the salt bridge intensive thermophilic proteins.
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Affiliation(s)
- Joachim M Vinther
- Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø, Denmark
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14
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Such-Sanmartín G, Bosch J, Segura J, Gutiérrez-Gallego R. Generation of 5 and 17 kDa human growth hormone fragments through limited proteolysis. Growth Factors 2009; 27:255-64. [PMID: 19603307 DOI: 10.1080/08977190903110121] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
INTRODUCTION The reported presence of two fragments of 5 and 17 kDa originating from the 22 kDa human growth hormone (hGH) in blood and tissues, postulated as the sequences AA 1-43 and AA 44-191, has led to the hypothesis of a post-translational proteolytic origin with respect to the abundant 22 kDa variant (AA 1-191). To evaluate this hypothesis, the activity of several endo-proteases on the 22 kDa hGH protein has been evaluated. METHODS Proteolysis using pepsin, trypsin, V8-protease, proteinase K and thermolysin were explored under several conditions, including incubation time and pH. Results were monitored by MALDI-TOF and HPLC-ESI mass spectrometry. Proteolytic 5 and 17 kDa fragments were purified through reversed phase HPLC-UV, and their immuno-affinity properties evaluated by surface plasmon resonance. RESULTS Thermolysin was shown to target mainly the AA 43-44 bond of the 22 kDa sequence at physiological pH. Interaction studies of the purified fragments with anti-GH antibodies showed some reactivity for the 17 kDa fragment. CONCLUSIONS Thermolysin processes hGH generating 5 and 17 kDa fragments, demonstrating the feasibility of this reaction, although the enzyme responsible for this process in humans is still unknown. Specific antibodies should be used to detect these fragments in human specimens, and, at the same time, the 17 kDa fragment could constitute an interference in some hGH immunoassays.
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Affiliation(s)
- Gerard Such-Sanmartín
- Bio-Analysis Group, Neuropsychopharmacology Program, Municipal Institute for Medical Research-Hospital del Mar, Parque de Investigación Biomédica de Barcelona, Barcelona, Spain
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15
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Jensen MR, Kristensen SM, Keeler C, Christensen HEM, Hodsdon ME, Led JJ. Weak self-association of human growth hormone investigated by nitrogen-15 NMR relaxation. Proteins 2009; 73:161-72. [PMID: 18409193 DOI: 10.1002/prot.22039] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The self-association of human growth hormone(hGH) was investigated using 15N NMR relaxation.The investigation relies on the 15N R1 and R2 relaxation rates and the heteronuclear{1H}-15N NOEs of the backbone amide groups at multiple protein concentrations. It is shown that the rotational correlation time of hGH in solution depends strongly on its concentration, indicating a significant degree of self-association.The self-association is reversible and the monomers in the aggregates are noncovalently linked. Extrapolation of the relaxation data to zero concentration predicts a correlation time of 13.4 ns and a rotational diffusion anisotropy of 1.26 for monomeric hGH, in agreement with the rotational diffusion properties estimated by hydrodynamic calculations. Moreover, the extrapolation allows characterization of the backbone dynamics of monomeric hGH without interference from self-association phenomena, and it is found that hGH is considerably more flexible than originally thought. A concerted least-squares analysis of the 15N relaxations and their concentration dependence reveals that the self-association goes beyond a simple monomer-dimer equilibrium, and that tetramers or other multimeric states co-exist in fast exchange with the monomeric and dimeric hGH at sub-millimolar concentrations. Small changes in the 1H and 15N amide chemical shifts suggest that a region around the C-terminus is involved in the oligomer formation.
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Affiliation(s)
- Malene Ringkjøbing Jensen
- Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø, Denmark
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16
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Such-Sanmartín G, Bosch J, Segura J, Wu M, Du H, Chen G, Wang S, Vila-Perelló M, Andreu D, Gutiérrez-Gallego R. Characterisation of the 5 kDa growth hormone isoform. Growth Factors 2008; 26:152-62. [PMID: 18569023 DOI: 10.1080/08977190802127952] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
OBJECTIVES The 5 kDa N-terminal fragment of 43 amino acids of human growth hormone (GH) shows a specific and significant in-vivo insulin-like activity. This isoform can be easily obtained by solid phase synthesis methods. Our objective in this study is to describe this procedure in detail and to provide structural information of the protein. METHODS Solid phase synthesis was employed for the synthesis of the 5 kDa GH isoform. Circular dichroism and limited proteolysis have been carried out to provide structural information about the folded state of the protein in solution. Surface plasmon resonance was used to compare the structural equivalence between the synthetic protein and a proteolytic homologue at an antibody binding level. For this purpose, a murine monoclonal antibody specific for the 5 kDa isoform was generated and characterised employing this and several other GH isoforms. RESULTS Circular dichroism and proteolysis results suggested that the C-terminal segment of the 5 kDa protein folds in an alpha-helix. The comparison of the synthetic product to its proteolytic homologue at an antibody binding level suggested structural equivalency. A highly specific antibody against the 5 kDa GH isoform was generated with null cross-reactivity for 17, 20 and 22 kDa isoforms. Kinetic data on the interaction with the synthetic 5 kDa GH was obtained. CONCLUSIONS The structure of the protein appears to be different in comparison to when it is included within the 22 kDa GH isoform. Finally, a highly specific antibody has been generated. The possible significance of the 5 kDa protein as a potential agent for obesity-related diseases is discussed.
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Affiliation(s)
- Gerard Such-Sanmartín
- Pharmacology Research Unit, Municipal Institute for Medical Research (IMIM), Barcelona, Spain
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17
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Hudáky P, Stráner P, Farkas V, Váradi G, Tóth G, Perczel A. Cooperation between a Salt Bridge and the Hydrophobic Core Triggers Fold Stabilization in a Trp-Cage Miniprotein. Biochemistry 2007; 47:1007-16. [DOI: 10.1021/bi701371x] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Péter Hudáky
- Laboratory of Structural Chemistry and Biology, Institute of Chemistry, Eötvös Loránd University, Pázmány Péter sétány 1/A, H-1117 Budapest, Hungary, Protein Modelling Group MTA-ELTE, Institute of Chemistry, Eötvös Loránd University, Pázmány Péter sétány 1/A, H-1117 Budapest, Hungary, and Department of Medical Chemistry, Faculty of General Medicine, University of Szeged, Dóm tér 8, H-6720 Szeged, Hungary
| | - Pál Stráner
- Laboratory of Structural Chemistry and Biology, Institute of Chemistry, Eötvös Loránd University, Pázmány Péter sétány 1/A, H-1117 Budapest, Hungary, Protein Modelling Group MTA-ELTE, Institute of Chemistry, Eötvös Loránd University, Pázmány Péter sétány 1/A, H-1117 Budapest, Hungary, and Department of Medical Chemistry, Faculty of General Medicine, University of Szeged, Dóm tér 8, H-6720 Szeged, Hungary
| | - Viktor Farkas
- Laboratory of Structural Chemistry and Biology, Institute of Chemistry, Eötvös Loránd University, Pázmány Péter sétány 1/A, H-1117 Budapest, Hungary, Protein Modelling Group MTA-ELTE, Institute of Chemistry, Eötvös Loránd University, Pázmány Péter sétány 1/A, H-1117 Budapest, Hungary, and Department of Medical Chemistry, Faculty of General Medicine, University of Szeged, Dóm tér 8, H-6720 Szeged, Hungary
| | - Györgyi Váradi
- Laboratory of Structural Chemistry and Biology, Institute of Chemistry, Eötvös Loránd University, Pázmány Péter sétány 1/A, H-1117 Budapest, Hungary, Protein Modelling Group MTA-ELTE, Institute of Chemistry, Eötvös Loránd University, Pázmány Péter sétány 1/A, H-1117 Budapest, Hungary, and Department of Medical Chemistry, Faculty of General Medicine, University of Szeged, Dóm tér 8, H-6720 Szeged, Hungary
| | - Gábor Tóth
- Laboratory of Structural Chemistry and Biology, Institute of Chemistry, Eötvös Loránd University, Pázmány Péter sétány 1/A, H-1117 Budapest, Hungary, Protein Modelling Group MTA-ELTE, Institute of Chemistry, Eötvös Loránd University, Pázmány Péter sétány 1/A, H-1117 Budapest, Hungary, and Department of Medical Chemistry, Faculty of General Medicine, University of Szeged, Dóm tér 8, H-6720 Szeged, Hungary
| | - András Perczel
- Laboratory of Structural Chemistry and Biology, Institute of Chemistry, Eötvös Loránd University, Pázmány Péter sétány 1/A, H-1117 Budapest, Hungary, Protein Modelling Group MTA-ELTE, Institute of Chemistry, Eötvös Loránd University, Pázmány Péter sétány 1/A, H-1117 Budapest, Hungary, and Department of Medical Chemistry, Faculty of General Medicine, University of Szeged, Dóm tér 8, H-6720 Szeged, Hungary
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18
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Jarymowycz VA, Stone MJ. Fast time scale dynamics of protein backbones: NMR relaxation methods, applications, and functional consequences. Chem Rev 2007; 106:1624-71. [PMID: 16683748 DOI: 10.1021/cr040421p] [Citation(s) in RCA: 317] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Virginia A Jarymowycz
- Department of Chemistry and Interdisciplinary Biochemistry Program, Indiana University, Bloomington, Indiana 47405-0001, USA
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19
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Keeler C, Jablonski EM, Albert YB, Taylor BD, Myszka DG, Clevenger CV, Hodsdon ME. The kinetics of binding human prolactin, but not growth hormone, to the prolactin receptor vary over a physiologic pH range. Biochemistry 2007; 46:2398-410. [PMID: 17279774 DOI: 10.1021/bi061958v] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A member of the family of hematopoietic cytokines, human prolactin (hPRL) serves a dual role both as an endocrine hormone and as an autocrine/paracrine cytokine or growth factor. During investigation of the solution structural properties of hPRL, we have noted a surprising pH dependence of its structural stability over a range from approximately pH 6.0 to pH 8.0. An analysis of backbone atom NMR chemical shift changes and backbone amide hydrogen-deuterium exchange rates due to titration of the solution pH over this same range, along with calculations of protein surface electrostatic potential, suggests the possible involvement of a localized cluster of three His residues (27, 30, and 180), which comprise a portion of the high-affinity receptor-binding epitope. Surface plasmon resonance analysis of the interaction between hPRL and the extracellular domain (ECD) of the hPRL receptor reveals a selective 500-fold change in the dissociation rate between pH 8.3 and pH 5.8. In comparison, the interaction of hGH with the same receptor ECD did not demonstrate any significant dependence on pH. We also present an initial investigation of the pH dependence of hPRL function in rat Nb2 cell proliferation assays and a STAT5 luciferase gene reporter assay in the T47D human breast cancer cell line, whose results are consistent with our biophysical studies. The potential implications of this variation in hPRL's structural stability and receptor-binding kinetics over this physiologic range of pH are discussed.
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Affiliation(s)
- Camille Keeler
- Department of Laboratory Medicine, Yale University, New Haven, Connecticut 06520, USA
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20
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Horn JR, Kraybill B, Petro EJ, Coales SJ, Morrow JA, Hamuro Y, Kossiakoff AA. The role of protein dynamics in increasing binding affinity for an engineered protein-protein interaction established by H/D exchange mass spectrometry. Biochemistry 2006; 45:8488-98. [PMID: 16834322 DOI: 10.1021/bi0604328] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
It is generally accepted that protein and solvation dynamics play fundamental roles in the mechanisms of protein-protein binding; however, assessing their contribution meaningfully has not been straightforward. Here, hydrogen/deuterium exchange mass spectrometry (H/D-Ex) was employed to assess the role of dynamics for a high-affinity human growth hormone variant (hGHv) and the wild-type growth hormone (wt-hGH) each binding to the extracellular domain of their receptor (hGHbp). Comparative analysis of the transient fluctuations in the bound and unbound states revealed that helix-1 of hGHv undergoes significant transient unfolding in its unbound state, a characteristic that was not found in wt-hGH or apparent in the temperature factor data from the X-ray analysis of the unbound hGHv structure. In addition, upon hormone binding, an overall increase in stability was observed for the beta-sheet structure of hGHbp which included sites distant from the binding interface. On the basis of the stability, binding kinetics, and thermodynamic data presented, the increase in the binding free energy of hGHv is primarily generated by factors that appear to increase the energy of the unbound state relative to the free energy of the bound complex. This implies that an alternate route to engineer new interactions aiming to increase protein-protein association energies may be achieved by introducing certain mutations that destabilize one of the interacting molecules without destabilizing the resulting bound complex. Importantly, although the hGHv molecule is less stable than its wt-hGH counterpart, its resulting active ternary complex with two copies of hGHbp has comparable stability to the wt complex.
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Affiliation(s)
- James R Horn
- Department of Biochemistry and Molecular Biology, The University of Chicago, 929 East 57th Street, Chicago, Illinois 60637, USA
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21
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Walsh STR, Kossiakoff AA. Crystal Structure and Site 1 Binding Energetics of Human Placental Lactogen. J Mol Biol 2006; 358:773-84. [PMID: 16546209 DOI: 10.1016/j.jmb.2006.02.038] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2006] [Revised: 02/10/2006] [Accepted: 02/14/2006] [Indexed: 11/18/2022]
Abstract
In primates, placental lactogen (PL) is a pituitary hormone with fundamental roles during pregnancy involving fetal growth, metabolism, and stimulating lactation in the mother. Human placental lactogen (hPL) is highly conserved with human growth hormone (hGH) and both hormones bind to the hPRLR extracellular domain (ECD), the first step in receptor homodimerization, in a Zn2+-dependent manner. A modified surface plasmon resonance method was developed to measure the kinetics for hPL and hGH binding to the hPRLR ECD, with and without Zn2+ and showed that hPL has about a tenfold higher affinity for the hPRLR ECD1 than hGH. The crystal structure of the free state of hPL has been determined to 2.0 A resolution showing the molecule possesses an overall structure similar to other long chain four-helix bundle cytokines. Comparison of the free hPL structure with the 1:1 complex structure of hGH bound to the hPRLR ECD1 suggests that two surface loops undergo conformational changes >10 A upon binding. An 18 residue Ala-scan was used to characterize the binding energy epitope for the site 1 interface of hPL. Individual alanine substitutions at five positions reduced binding affinity by a DeltaDeltaG > or = 3 kcal mol(-1). A comparison of the hPL site 1 epitope with that previously determined for hGH indicates contributions of individual residues track reasonably well between hPL and hGH. In particular, residues involved in the zinc-binding site and Lys172 constitute the principal binding determinants for both hormones. However, several residues that are identical between hPL and hGH contribute quite differently to the binding of the hPRLR ECD1. Additionally, the overall magnitudes of the DeltaDeltaG changes observed from the Ala-scan of hPL were markedly larger than those determined in the comparative scan of hGH to the hPRLR ECD1. The structural and biophysical data presented here show that subtle changes in the structural context of an interaction can lead to significantly different effects at the individual residue level.
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Affiliation(s)
- Scott T R Walsh
- Department of Molecular and Cellular Biochemistry, Ohio State University, 467 Hamilton Hall, 1645 Neil Avenue Columbus, OH 43210, USA
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22
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Saboury AA, Atri MS, Sanati MH, Moosavi-Movahedi AA, Hakimelahi GH, Sadeghi M. A thermodynamic study on the interaction between magnesium ion and human growth hormone. Biopolymers 2006; 81:120-6. [PMID: 16208769 DOI: 10.1002/bip.20386] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
A thermodynamic study on the interaction between magnesium ion and human growth hormone (hGH) was studied at 27 degrees C in NaCl solution (50 mM) using different techniques. Two techniques of ionmetry using a Mg2+selective membrane electrode and isothermal titration calorimetry were applied to obtain the binding isotherm for hGHMg2+; results obtained by both techniques were found to be in good agreement. There is a set of three identical and noninteracting binding sites for magnesium ions. The intrinsic dissociation equilibrium constant and the molar enthalpy of binding are 46 microM and -17.7 kJ/mol, respectively. Temperature scanning UV-visible spectroscopy was applied to elucidate the effect of Mg2+ binding on the protein stability, and circular dichroism (CD) spectroscopy was used to show the structural change of hGH due to the metal ion interaction. Magnesium ion binding increased the protein thermal stability by increasing the alpha-helix content as well as decreasing both beta and random coil structures. However, the secondary structural change of the protein returns to its native form, including a small change in the tertiary structure, in high concentrations of magnesium ion.
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Affiliation(s)
- A A Saboury
- Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran.
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23
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Teilum K, Hoch JC, Goffin V, Kinet S, Martial JA, Kragelund BB. Solution structure of human prolactin. J Mol Biol 2005; 351:810-23. [PMID: 16045928 DOI: 10.1016/j.jmb.2005.06.042] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2005] [Revised: 06/16/2005] [Accepted: 06/17/2005] [Indexed: 11/20/2022]
Abstract
We report the solution structure of human prolactin determined by NMR spectroscopy. Our result is a significant improvement over a previous structure in terms of number and distribution of distance restraints, regularity of secondary structure, and potential energy. More significantly, the structure is sufficiently different that it leads to different conclusions regarding the mechanism of receptor activation and initiation of signal transduction. Here, we compare the structure of unbound prolactin to structures of both the homologue ovine placental lactogen and growth hormone. The structures of unbound and receptor bound prolactin/placental lactogen are similar and no noteworthy structural changes occur upon receptor binding. The observation of enhanced binding at the second receptor site when the first site is occupied has been widely interpreted to indicate conformational change induced by binding the first receptor. However, our results indicate that this enhanced binding at the second site could be due to receptor-receptor interactions or some other free energy sources rather than conformational change in the hormone. Titration of human prolactin with the extracellular domain of the human prolactin receptor was followed by NMR, gel filtration and electrophoresis. Both binary and ternary hormone-receptor complexes are clearly detectable by gel filtration and electrophoresis. The binary complex is not observable by NMR, possibly due to a dynamic equilibrium in intermediate exchange within the complex. The ternary complex of one hormone molecule bound to two receptor molecules is on the contrary readily detectable by NMR. This is in stark contrast to the widely held view that the ternary prolactin-receptor complex is only transiently formed. Thus, our results lead to improved understanding of the prolactin-prolactin receptor interaction.
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Affiliation(s)
- Kaare Teilum
- Department of Protein Chemistry, Institute of Molecular Biology and Physiology, University of Copenhagen, Øster Farimagsgade 2A, DK-1353 Copenhagen K, Denmark
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24
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Saboury AA, Atri MS, Sanati MH, Moosavi-Movahedi AA, Haghbeen K. Effects of calcium binding on the structure and stability of human growth hormone. Int J Biol Macromol 2005; 36:305-9. [PMID: 16102809 DOI: 10.1016/j.ijbiomac.2005.07.003] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2005] [Revised: 07/11/2005] [Accepted: 07/11/2005] [Indexed: 11/25/2022]
Abstract
Thermodynamic analysis of calcium ions binding to human growth hormone (hGH) was done at 27 degrees C in NaCl solution, 50 mM, using different techniques. The binding isotherm for hGH-Ca2+ was obtained by two techniques of ionmetry, using a Ca(2+)-selective membrane electrode, and isothermal titration calorimetry. Results obtained by two ionmetric and calorimetric methods are in good agreement. There is a set of three identical and non-interacting binding sites for calcium ions. The intrinsic dissociation equilibrium constant and the molar enthalpy of binding are 52 microM and -17.4 kJ/mol, respectively. Temperature scanning UV-vis spectroscopy was applied to elucidate the effect of Ca2+ binding on the protein stability, and circular dichroism (CD) spectroscopy was used to show the structural change of hGH due to the metal ion interaction. Calcium ions binding increase the protein thermal stability by increasing of the alpha helix content as well as decreasing of both beta and random coil structures.
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Affiliation(s)
- A A Saboury
- Institute of Biochemistry and Biophysics, University of Tehran, Enghelab Street, Tehran 1417614411, Iran.
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25
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Spolaore B, Polverino de Laureto P, Zambonin M, Fontana A. Limited proteolysis of human growth hormone at low pH: isolation, characterization, and complementation of the two biologically relevant fragments 1-44 and 45-191. Biochemistry 2004; 43:6576-86. [PMID: 15157090 DOI: 10.1021/bi049491g] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The limited proteolysis approach was used to analyze the conformational features of human growth hormone (hGH) under acidic solvent conditions (A-state). Pepsin was used as the proteolytic probe because of its poor substrate specificity and its activity at low pH. Limited proteolysis of hGH in its A-state results in a selective cleavage of the Phe44-Leu45 peptide bond, leading to the production of fragments 1-44 and 45-191. The two fragments were isolated in homogeneous form for studying their conformational properties by means of spectroscopic methods. Fragment 1-44 was shown to retain little secondary and tertiary structure at neutral pH, while fragment 45-191 independently folds into a highly helical secondary structure. In particular, we have shown that the two peptic fragments are able to associate into a stable and native-like hGH complex 1-44/45-191. Our proteolysis data indicate that in acid solution hGH adopts a partly folded state characterized by a local unfolding of the first minihelix (residues 38-47) encompassing the Phe44-Leu45 peptide bond. Of interest, hGH has both insulin-like and diabetogenic effects. Two fragments of hGH occur in vivo and exert these two opposite activities, namely, fragment 1-43 showing an insulin-potentiating effect and fragment 44-191 showing a diabetogenic activity. The results of this study suggest that the conformational changes of hGH induced by an acidic pH promote the generation of the two physiologically relevant fragments by proteolytic processing of the hormone. Although pepsin cannot be the enzyme responsible for the in vivo processing of the hormone, we propose that limited proteolysis of hGH at low pH is physiologically relevant, since the hormone is exposed to an acidic environment in the cell. This study reports for the first time the analysis of the conformational features of the two individual functional domains of hGH and of their complex.
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Affiliation(s)
- Barbara Spolaore
- CRIBI Biotechnology Centre, University of Padua, Viale G. Colombo 3, 35121 Padua, Italy
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26
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Keeler C, Hodsdon ME, Dannies PS. Is there structural specificity in the reversible protein aggregates that are stored in secretory granules? J Mol Neurosci 2004; 22:43-9. [PMID: 14742909 DOI: 10.1385/jmn:22:1-2:43] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2003] [Accepted: 10/01/2003] [Indexed: 11/11/2022]
Abstract
There are several steps that must occur for secretory granules to form: (1) Secretory proteins that make up the dense cores of the granules must be concentrated; (2) membrane proteins necessary for granule function must accumulate in the correct location; and (3) inappropriate membrane proteins and excess membrane must be removed. Reversible aggregation of secretory granule proteins provides a mechanism for concentrating and sorting these proteins. There is specificity in the way secretory granule proteins are treated in cells that make granules. The specificity has been shown in some cases to occur after the aggregation process, so that granules containing different aggregates function differently. An explanation could be that a property of the aggregate, such as a surface motif, might influence the accumulation of membrane proteins necessary for granule function. Such a conclusion implies that the aggregates are not amorphous but have structure. Use of NMR spectroscopy to investigate changes in the environment of amino acid residues in secretory granule proteins as they form oligomers by using 15N relaxation times might provide a means to determine which residues are specifically involved in aggregation.
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Affiliation(s)
- Camille Keeler
- Department of Pharmacology and Department of Laboratory Medicine, Yale University School of Medicine, New Haven, CT 06520, USA
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27
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Hu H, Clarkson MW, Hermans J, Lee AL. Increased rigidity of eglin c at acidic pH: evidence from NMR spin relaxation and MD simulations. Biochemistry 2004; 42:13856-68. [PMID: 14636053 DOI: 10.1021/bi035015z] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
To gain physical insights into how proteins respond to changes in pH, the picosecond to nanosecond time scale dynamics of the small serine protease inhibitor eglin c have been studied by NMR spin relaxation experiments and MD simulations under two pH solution conditions, pH 7 and 3. Like many proteins, eglin c is destabilized by a lowering of the pH, although it retains enough stability to maintain its native conformation at pH 3. Backbone (15)N relaxation results show comparable global tumbling times (tau(m)) and model-free order parameters (S(2)) under the two pH conditions, indicating that the molecule maintains its overall molecular shape and structure at low pH, although the backbone rigidity is slightly increased (<DeltaS(pH3-pH7)(2)>/<S(2)> = 0.6%). In contrast, the side-chain methyl dynamics, as measured from (2)H relaxation experiments, show a substantial increase in rigidity at lower pH (<DeltaS(axis,pH3-pH7)(2)>/<S(axis)(2)> = 14.8%). Molecular dynamics simulations performed at these pH states produce results consistent with NMR measurements, showing that the two methods are in qualitative agreement. Although a full accounting of the physical basis for the concurrent conformational rigidification and destabilization at low pH requires further investigation, the high level of detail in the MD simulations provides a potential molecular mechanism: the breaking of the hydrogen bond between the side chains of Asp46 and Arg53, and changes in electrostatic interactions, appear to allow the binding loop to move closer to the core part of the protein, resulting in a more compact structure at low pH. This more compact structure may be responsible for the increased level of restriction of molecular motion. As these findings show, the stability of a molecular structure is distinct from its conformational rigidity, and the two can even change in opposite directions, against naïve expectation.
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Affiliation(s)
- Hao Hu
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
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28
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Branson KM, Smith BJ. The Role of Virtual Screening in Computer Aided Structure-Based Drug Design. Aust J Chem 2004. [DOI: 10.1071/ch04161] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The pharmaceutical industry has embraced computational methods to improve the successful negotiation of hits and leads into drugs in the clinic. This review examines the current status of in silico screening methods and aspects of compound library design.
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29
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Abstract
Human prolactin is a 199-residue (23 kDa) protein closely related to growth hormone and placental lactogen with properties and functions resembling both a hormone and a cytokine. As a traditional hormone, prolactin is produced by lactotrophic cells in the pituitary and secreted into the bloodstream where it acts distally to regulate reproduction and promote lactation. Pituitary cells store prolactin in secretory granules organized around large prolactin aggregates, which are produced within the trans layer of the Golgi complex. Extrapituitary prolactin is synthesized by a wide variety of cells but is not stored in secretory granules. Extrapituitary prolactin displays immunomodulatory activities and acts as a growth factor for cancers of the breast, prostate and tissues of the female reproductive system. We have determined the tertiary structure of human prolactin using three-dimensional (3D) and four-dimensional (4D) heteronuclear NMR spectroscopy. As expected, prolactin adopts an "up-up-down-down" four-helical bundle topology and resembles other members of the family of hematopoietic cytokines. Prolactin displays three discrete structural differences from growth hormone: (1) a structured N-terminal loop in contact with the first helix, (2) a missing mini-helix in the loop between the first and second helices, and (3) a shorter loop between the second and third helices lacking the perpendicular mini-helix observed in growth hormone. Residues necessary for functional binding to the prolactin receptor are clustered on the prolactin surface in a position similar to growth hormone. The backbone dynamics of prolactin were investigated by analysis of 15N NMR relaxation phenomena and demonstrated a rigid four-helical bundle with relatively mobile interconnecting loops. Comparison of global macromolecular tumbling at 0.1mM and 1.0mM prolactin revealed reversible oligomerization, which was correlated to dynamic light scattering experiments. The existence of a reversible oligomerization reaction in solution provides insight into previous results describing the in vitro and in vivo aggregation properties of human prolactin.
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Affiliation(s)
- Camille Keeler
- Department of Laboratory Medicine, Yale University School of Medicine, New Haven, CT 06520-8035, USA
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30
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Ma L, Hass MAS, Vierick N, Kristensen SM, Ulstrup J, Led JJ. Backbone dynamics of reduced plastocyanin from the cyanobacterium Anabaena variabilis: regions involved in electron transfer have enhanced mobility. Biochemistry 2003; 42:320-30. [PMID: 12525159 DOI: 10.1021/bi020553h] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The dynamics of the backbone of the electron-transfer protein plastocyanin from the cyanobacterium Anabaena variabilis were determined from the (15)N and (13)C(alpha) R(1) and R(2) relaxation rates and steady-state [(1)H]-(15)N and [(1)H]-(13)C nuclear Overhauser effects (NOEs) using the model-free approach. The (13)C relaxation studies were performed using (13)C in natural abundance. Overall, it is found that the protein backbone is rigid. However, the regions that are important for the function of the protein show moderate mobility primarily on the microsecond to millisecond time scale. These regions are the "northern" hydrophobic site close to the metal site, the metal site itself, and the "eastern" face of the molecule. In particular, the mobility of the latter region is interesting in light of recent findings indicating that residues also on the eastern face of plastocyanins from prokaryotes are important for the function of the protein. The study also demonstrates that relaxation rates and NOEs of the (13)C(alpha) nuclei of proteins are valuable supplements to the conventional (15)N relaxation measurements in studies of protein backbone dynamics.
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Affiliation(s)
- Lixin Ma
- Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø, Denmark
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