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Wang S, Wang M, Han L, Sun Y, Cai W, Shao X. Insight into the stability of protein in confined environment through analyzing the structure of water by temperature-dependent near-infrared spectroscopy. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2022; 267:120581. [PMID: 34776375 DOI: 10.1016/j.saa.2021.120581] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Revised: 10/13/2021] [Accepted: 11/01/2021] [Indexed: 06/13/2023]
Abstract
To understand the stability of protein in confined environment, the near-infrared (NIR) spectra of aqueous solutions and reverse micelles (RMs) containing bovine serum albumin (BSA), human serum albumin (HSA) and ovalbumin (OVA) were measured at different temperature. With the resolution enhanced spectra calculated by continuous wavelet transform (CWT), the intensity change of the α-helix band at 4617 cm-1 with temperature shows a clear denaturation of the protein in aqueous solution but not in RMs. The effect of the confined environment on the stability of the proteins is indicated. More importantly, the intensity change of the spectral bands of water around 6956 and 6842 cm-1 provide an evidence for the denaturation, suggesting that water can be a probe exhibiting the structural change of proteins. Furthermore, comparing the spectral features of different water structures obtained by principal component analysis (PCA) from the spectra of RM with and without BSA, it is demonstrated that the bridging water connecting NH in protein and SO in the inner surface of RM may be the reason for the stabilization.
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Affiliation(s)
- Shiying Wang
- Research Center for Analytical Sciences, Frontiers Science Center for New Organic Matter, College of Chemistry, Nankai University, Tianjin Key Laboratory of Biosensing and Molecular Recognition, State Key Laboratory of Medicinal Chemical Biology, Tianjin 300071, PR China
| | - Mian Wang
- Research Center for Analytical Sciences, Frontiers Science Center for New Organic Matter, College of Chemistry, Nankai University, Tianjin Key Laboratory of Biosensing and Molecular Recognition, State Key Laboratory of Medicinal Chemical Biology, Tianjin 300071, PR China
| | - Li Han
- Research Center for Analytical Sciences, Frontiers Science Center for New Organic Matter, College of Chemistry, Nankai University, Tianjin Key Laboratory of Biosensing and Molecular Recognition, State Key Laboratory of Medicinal Chemical Biology, Tianjin 300071, PR China
| | - Yan Sun
- Research Center for Analytical Sciences, Frontiers Science Center for New Organic Matter, College of Chemistry, Nankai University, Tianjin Key Laboratory of Biosensing and Molecular Recognition, State Key Laboratory of Medicinal Chemical Biology, Tianjin 300071, PR China
| | - Wensheng Cai
- Research Center for Analytical Sciences, Frontiers Science Center for New Organic Matter, College of Chemistry, Nankai University, Tianjin Key Laboratory of Biosensing and Molecular Recognition, State Key Laboratory of Medicinal Chemical Biology, Tianjin 300071, PR China
| | - Xueguang Shao
- Research Center for Analytical Sciences, Frontiers Science Center for New Organic Matter, College of Chemistry, Nankai University, Tianjin Key Laboratory of Biosensing and Molecular Recognition, State Key Laboratory of Medicinal Chemical Biology, Tianjin 300071, PR China.
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2
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Senske M, Xu Y, Bäumer A, Schäfer S, Wirtz H, Savolainen J, Weingärtner H, Havenith M. Local chemistry of the surfactant's head groups determines protein stability in reverse micelles. Phys Chem Chem Phys 2018. [DOI: 10.1039/c8cp00407b] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Protein stability in reverse micelles is determined by local chemical interactions between the surfactant molecules and the protein groups.
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Affiliation(s)
- Michael Senske
- Department of Physical Chemistry II
- Ruhr-Universität Bochum
- 44780 Bochum
- Germany
| | - Yao Xu
- Department of Physical Chemistry II
- Ruhr-Universität Bochum
- 44780 Bochum
- Germany
| | - Alexander Bäumer
- Department of Physical Chemistry II
- Ruhr-Universität Bochum
- 44780 Bochum
- Germany
| | - Sarah Schäfer
- Department of Physical Chemistry II
- Ruhr-Universität Bochum
- 44780 Bochum
- Germany
| | - Hanna Wirtz
- Department of Physical Chemistry II
- Ruhr-Universität Bochum
- 44780 Bochum
- Germany
| | - Janne Savolainen
- Department of Physical Chemistry II
- Ruhr-Universität Bochum
- 44780 Bochum
- Germany
| | - Hermann Weingärtner
- Department of Physical Chemistry II
- Ruhr-Universität Bochum
- 44780 Bochum
- Germany
| | - Martina Havenith
- Department of Physical Chemistry II
- Ruhr-Universität Bochum
- 44780 Bochum
- Germany
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3
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Senske M, Smith AE, Pielak GJ. Protein Stability in Reverse Micelles. Angew Chem Int Ed Engl 2016; 55:3586-9. [DOI: 10.1002/anie.201508981] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Revised: 12/14/2015] [Indexed: 02/06/2023]
Affiliation(s)
- Michael Senske
- Department of Physical Chemistry II; Ruhr-Universität Bochum; 44780 Bochum Germany
| | - Austin E. Smith
- Department of Chemistry; University of North Carolina at Chapel Hill; Chapel Hill NC 27599-3290 USA
| | - Gary J. Pielak
- Department of Chemistry; University of North Carolina at Chapel Hill; Chapel Hill NC 27599-3290 USA
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4
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Affiliation(s)
- Michael Senske
- Department of Physical Chemistry II Ruhr-Universität Bochum 44780 Bochum Germany
| | - Austin E. Smith
- Department of Chemistry University of North Carolina at Chapel Hill Chapel Hill NC 27599-3290 USA
| | - Gary J. Pielak
- Department of Chemistry University of North Carolina at Chapel Hill Chapel Hill NC 27599-3290 USA
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Choukair D, Beuschlein F, Zwermann O, Wudy SA, Haufe S, Holland-Cunz S, Bettendorf M. Virilization of a young girl caused by concomitant ectopic and intra-adrenal adenomas of the adrenal cortex. Horm Res Paediatr 2014; 79:318-22. [PMID: 23711916 DOI: 10.1159/000350244] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/06/2012] [Accepted: 02/26/2013] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Adenomas of the adrenal gland are rare causes of virilization in childhood. CASE REPORT A girl aged 2 years and 4 months presented with pubarche, distinct clitoral hypertrophy, tall stature, and increased height velocity. Plasma testosterone and dehydroepiandrosterone were elevated. Androgens remained unchanged after adrenocorticotropic hormone, and dexamethasone administrations. Ultrasound examination and magnetic resonance imaging indicated an extra-adrenal mass adjacent to the left adrenal gland, which was removed by endoscopic surgery. However, plasma androgens remained elevated and (131)I-iodomethyl-norcholesterol scintigraphy revealed tracer enhancement in the right adrenal gland, which was consecutively removed. Virilization regressed after extirpation of the adenomas and height velocity normalized. RESULTS Histology revealed a circumscribed adenoma in the right adrenal gland and an epithelial mass with adrenal cortical cells in the left-sided ectopic tumor. In the ectopic tumor, melanocortin 2 receptor expression was augmented threefold compared to the control, indicating adrenal origin. CONCLUSIONS In this young girl, virilization is due to concomitant ectopic and intra-adrenal adenomas of the adrenal cortex. By melanocortin 2 receptor expression, it was confirmed that the ectopic adenoma derived from the adrenal cortex. Specific scintigraphy, if available, assists in allocating the source of androgen hypersecretion.
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Affiliation(s)
- Daniela Choukair
- Division of Pediatric Endocrinology, University Children's Hospital Heidelberg, DE-69120 Heidelberg, Germany.
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6
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Pawar MG, Srivatsan SG. Environment-responsive fluorescent nucleoside analogue probe for studying oligonucleotide dynamics in a model cell-like compartment. J Phys Chem B 2013; 117:14273-82. [PMID: 24161106 DOI: 10.1021/jp4071168] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The majority of fluorescent nucleoside analogue probes that have been used in the in vitro study of nucleic acids are not suitable for cell-based biophysical assays because they exhibit excitation maxima in the UV region and low quantum yields within oligonucleotides. Therefore, we propose that the photophysical characterization of oligonucleotides labeled with a fluorescent nucleoside analogue in reverse micelles (RM), which are good biological membrane models and UV-transparent, could provide an alternative approach to studying the properties of nucleic acids in a cell-like confined environment. In this context, we describe the photophysical properties of an environment-sensitive fluorescent uridine analogue (1), based on the 5-(benzo[b]thiophen-2-yl)pyrimidine core, in micelles and RM. The emissive nucleoside, which is polarity- and viscosity-sensitive, reports the environment of the surfactant assemblies via changes in its fluorescence properties. The nucleoside analogue, incorporated into an RNA oligonucleotide and hybridized to its complementary DNA and RNA oligonucleotides, exhibits a significantly higher fluorescence intensity, lifetime, and anisotropy in RM than in aqueous buffer, which is consistent with the environment of RM. Collectively, our results demonstrate that nucleoside 1 could be utilized as a fluorescent label to study the function of nucleic acids in a model cellular milieu.
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Affiliation(s)
- Maroti G Pawar
- Department of Chemistry, Indian Institute of Science Education and Research, Pune , Dr. Homi Bhabha Road, Pashan, Pune 411008, India
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7
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Studying salt effects on protein stability using ribonuclease t1 as a model system. Biophys Chem 2011; 161:29-38. [PMID: 22197350 DOI: 10.1016/j.bpc.2011.11.004] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2011] [Revised: 11/22/2011] [Accepted: 11/22/2011] [Indexed: 11/21/2022]
Abstract
Salt ions affect protein stability in a variety of ways. In general, these effects have either been interpreted from a charge solvation/charge screening standpoint or they have been considered to be the result of ion-specific interactions with a particular protein. Recent theoretical work suggests that a major contribution to salt effects on proteins is through the interaction of salt ions that are located near the protein surface and their induced point image charges that are located in the low-dielectric protein cavity. These interactions form the basis of "salting-out" interactions. Salt ions induce an image charge of the same sign in the low dielectric protein medium. The interaction between the induced charge and its mirror charge is repulsive and consequently thermodynamically destabilizing. However, a folded protein that has a much smaller surface area will be less destabilized than the unfolded state. Consequently, the folded state will be stabilized relative to the unfolded state. This work analyzes salt effects in the model enzyme ribonuclease t1, and demonstrates that interactions between salt ions and their induced point charges provide a major contribution to the observed salt-induced increase in protein stability. This work also demonstrates that in the case of weakly-binding ions (ions with binding constants that are in the order of 50 M(-1) and less), salting-out effects should still be considered in order to provide a more realistic interpretation of ion binding. These results should therefore be considered when salt effects are used to analyze electrostatic contributions to protein structure or are used to study the thermodynamics of proteins associated with halophillic organisms.
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8
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Liu Y, Liu Y, Guo R. Effect of Cyclodextrins on the Interaction Between BSA and Sodium Dodecyl Benzene Sulfonate. J SOLUTION CHEM 2011. [DOI: 10.1007/s10953-011-9712-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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9
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Madeira C, Estrela N, Ferreira JAB, Andrade SM, Costa SMB, Melo EP. Fluorescence lifetime imaging microscopy and fluorescence resonance energy transfer from cyan to yellow fluorescent protein validates a novel method to cluster proteins on solid surfaces. JOURNAL OF BIOMEDICAL OPTICS 2009; 14:044035. [PMID: 19725746 DOI: 10.1117/1.3210770] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
A novel method to distribute proteins on solid surfaces is proposed. Proteins microencapsulated in the water pool of reverse micelles were used to coat a solid surface with well-individualized round spots of 1 to 3 microm in diameter. The number of spots per unit area can be increased through the concentration of reverse micelles, and networks of spots were obtained at high concentrations of large reverse micelles. Moreover, depending on the pool size of the water reverse micelles, proteins can be deposited far from each other or in close proximity within the range of 50 to 70 A. This proximity obtained with small reverse micelles was proved through fluorescence lifetime imaging microscopy and fluorescence resonance energy transfer (FLIM-FRET) measurements for the most relevant FRET pair in cell biology studies, the cyan and yellow fluorescent proteins. This novel procedure has several advantages and reveals the potential for study of protein-protein interactions on solid surfaces and for developing novel biomaterials and molecular devices based on biorecognition elements.
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Affiliation(s)
- Catarina Madeira
- Institute for Biotechnology and Bioengineering, Centre for Biological and Chemical Engineering, Instituto Superior Tecnico, Av Rovisco Pais, Lisbon, 1049-001, Portugal
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10
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Davidovic M, Mattea C, Qvist J, Halle B. Protein Cold Denaturation as Seen From the Solvent. J Am Chem Soc 2008; 131:1025-36. [DOI: 10.1021/ja8056419] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Monika Davidovic
- Department of Biophysical Chemistry, Center for Molecular Protein Science, Lund University, SE-22100 Lund, Sweden
| | - Carlos Mattea
- Department of Biophysical Chemistry, Center for Molecular Protein Science, Lund University, SE-22100 Lund, Sweden
| | - Johan Qvist
- Department of Biophysical Chemistry, Center for Molecular Protein Science, Lund University, SE-22100 Lund, Sweden
| | - Bertil Halle
- Department of Biophysical Chemistry, Center for Molecular Protein Science, Lund University, SE-22100 Lund, Sweden
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11
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Fan JB, Chen J, Liang Y. Oxidative refolding of reduced, denatured lysozyme in AOT reverse micelles. J Colloid Interface Sci 2008; 322:95-103. [DOI: 10.1016/j.jcis.2008.02.057] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2007] [Revised: 02/19/2008] [Accepted: 02/24/2008] [Indexed: 11/29/2022]
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12
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Interaction of 8-hydroxypyrene-1,3,6-trisulphonate in alkyltrimethylammonium bromide (CnTAB) micellar medium. J Photochem Photobiol A Chem 2007. [DOI: 10.1016/j.jphotochem.2006.11.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
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13
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Abstract
Nonspecific interactions between individual macro-molecules and their immediate surroundings ("background interactions") within a medium as heterogeneous and highly volume occupied as the interior of a living cell can greatly influence the equilibria and rates of reactions in which they participate. Background interactions may be either repulsive, leading to preferential size-and-shape-dependent exclusion from highly volume-occupied elements of volume, or attractive, leading to nonspecific associations or adsorption. Nonspecific interactions with different constituents of the cellular interior lead to three classes of phenomena: macromolecular crowding, confinement and adsorption. Theory and experiment have established that predominantly repulsive background interactions tend to enhance the rate and extent of macromolecular associations in solution, whereas predominantly attractive background interactions tend to enhance the tendency of macromolecules to associate on adsorbing surfaces. Greater than order-of-magnitude increases in association rate and equilibrium constants attributable to background interactions have been observed in simulated and actual intracellular environments.
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Affiliation(s)
- Allen P Minton
- Section on Physical Biochemistry, Laboratory of Biochemical Pharmacology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health/U.S. DHHS, Bethesda, MD 20892, USA.
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14
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Sarkar R, Shaw AK, Narayanan SS, Dias F, Monkman A, Pal SK. Direct observation of protein folding in nanoenvironments using a molecular ruler. Biophys Chem 2006; 123:40-8. [PMID: 16697515 DOI: 10.1016/j.bpc.2006.04.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2006] [Revised: 04/06/2006] [Accepted: 04/11/2006] [Indexed: 11/22/2022]
Abstract
We observe folding of horse heart cytochrome c in various environments including nano-compartments (micelles and reverse micelles). Using picosecond-resolved Förster resonance energy transfer (FRET) dynamics of an extrinsic covalently attached probe dansyl (donor) at the surface of the protein to a heme group (acceptor) embedded inside the protein, we measured angstrom-resolved donor-acceptor distances in the environments. The overall structural perturbations of the protein revealed from the FRET experiments are in close agreement with our circular dichroism (CD) and dynamic light scattering (DLS) studies on the protein in a variety of solution conditions. The change of segmental motion of the protein due to imposed restriction in the nano-compartments compared to that in bulk buffer is also revealed by temporal fluorescence anisotropy of the dansyl probe.
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Affiliation(s)
- Rupa Sarkar
- Unit for Nano Science and Technology, SN Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata, India
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15
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Rialdi G, Battistel E. Thermodynamics of proteins in unusual environments. Biophys Chem 2006; 126:65-79. [PMID: 16814921 DOI: 10.1016/j.bpc.2006.05.029] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2006] [Revised: 05/26/2006] [Accepted: 05/26/2006] [Indexed: 11/19/2022]
Abstract
Some aspects of protein thermodynamics in unconventional environments are addressed and discussed. Aqueous medium, especially dilute solution is the 'usual' ambient, which mediates all the interactions between protein and nearby molecules. When the water content is low, the surroundings may be considered 'unusual', exerting new stresses on the protein molecule and demanding different responses and property changes. The unusual systems considered in this article are low-water protein environments, including nearly dry state powders, organic solvent dispersions and reverse micelles' inclusions. The changes of hydration experienced by the protein after immobilization on solid supports are emphasized with respect to the free bulk solution state. Finally, the aqueous medium altered by water connectivity perturbing agents (polysaccharides) or in macromolecular crowding conditions (in the presence of polyols) is also considered as highly not ideal protein environments. The different responses elicited by the protein under the stress induced by drastic surrounding alterations may give insights for the controlled exploitation of the protein's biological and thermodynamic properties.
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16
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Meersman F, Dirix C, Shipovskov S, Klyachko NL, Heremans K. Pressure-induced protein unfolding in the ternary system AOT-octane-water is different from that in bulk water. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2005; 21:3599-3604. [PMID: 15807607 DOI: 10.1021/la0470481] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
In a cellular environment, the presence of macromolecular cosolutes and membrane interfaces can influence the folding-unfolding behavior of proteins. Here we report on the pressure stability of alpha-chymotrypsin in the ternary system bis(2-ethylhexyl)sodium sulfosuccinate-octane-water using FTIR spectroscopy. The ternary system forms anionic reverse micelles which mimic cellular conditions. We find that inclusion of a single protein molecule in a reverse micelle does not alter its conformation. When pressurized in bulk water, alpha-chymotrypsin unfolds at 750 MPa into a partially unfolded structure. In contrast, in the ternary system, the same pressure increase induces a random coil-like unfolded state, which collapses into an amorphous aggregate during the decompression phase. It is suggested that the unfolding pathway is different in a cell-mimicking environment due to the combined effect of multiple factors, including confinement. A phase transition of the reverse micellar to the lamellar phase is thought to be essential to provide the conditions required for unfolding and aggregation, though the unfolding is not a direct result of the phase transition. Our observations therefore suggest that membranes may cause the formation of alternative conformations that are more susceptible to aggregation.
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Affiliation(s)
- Filip Meersman
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom.
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17
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Vincent M, de Foresta B, Gallay J. Nanosecond dynamics of a mimicked membrane-water interface observed by time-resolved stokes shift of LAURDAN. Biophys J 2005; 88:4337-50. [PMID: 15778437 PMCID: PMC1305662 DOI: 10.1529/biophysj.104.057497] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We studied the dipolar relaxation of the surfactant-water interface in reverse micelles of AOT-water in isooctane in the nanosecond and subnanosecond time ranges by incorporating the amphipathic solvatochromic fluorescent probes LAURDAN and TOE. A negative component was observed in the fluorescence decays in the red edge of the emission spectrum-the signature of an excited state reaction-with LAURDAN but not for TOE. The deconvolution of the transient reconstructed spectra of LAURDAN based on a model constructed by adding together three log-normal Gaussian equations made it possible to separate the specific dynamic solvent response from the intramolecular excited state reactions of the probe. The deconvoluted spectrum of lowest energy displayed the largest Stokes shift. This spectral shift was described by unimodal kinetics on the nanosecond timescale, whereas the relaxation kinetics of water-soluble probes have been reported to be biphasic (on the subnanosecond and nanosecond timescales) due to the heterogeneous distribution of these probes in the water pool. Most of this spectral shift probably resulted from water relaxation as it was highly sensitive to the water to surfactant molar ratio (w(0)) (60-65 nm at w(0) = 20-30). A small part of this spectral shift (9 nm at w(0) = 0) probably resulted from dipolar interaction with the AOT polar headgroup. The measured relaxation time values were in the range of the rotational motion of the AOT polar headgroup region as assessed by LAURDAN and TOE fluorescence anisotropy decays.
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Affiliation(s)
- Michel Vincent
- LURE Laboratoire pour l'Utilisation du Rayonnement Electromagnétique, Université Paris-Sud, Bâtiment 209D, Orsay, France
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18
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Babu CR, Hilser VJ, Wand AJ. Direct access to the cooperative substructure of proteins and the protein ensemble via cold denaturation. Nat Struct Mol Biol 2004; 11:352-7. [PMID: 14990997 DOI: 10.1038/nsmb739] [Citation(s) in RCA: 117] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2003] [Accepted: 02/03/2004] [Indexed: 11/09/2022]
Abstract
The modern view of protein thermodynamics predicts that proteins undergo cold-induced unfolding. Unfortunately, the properties of proteins and water conspire to prevent the detailed observation of this fundamental process. Here we use protein encapsulation to allow cold denaturation of the protein ubiquitin to be monitored by high-resolution NMR at temperatures approaching -35 degrees C. The cold-induced unfolding of ubiquitin is found to be highly noncooperative, in distinct contrast to the thermal melting of this and other proteins. These results demonstrate the potential of cold denaturation as a means to dissect the cooperative substructures of proteins and to provide a rigorous framework for testing statistical thermodynamic treatments of protein stability, dynamics and function.
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Affiliation(s)
- Charles R Babu
- Johnson Research Foundation and Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6059, USA
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19
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SDS-induced conformational transitions of ervatamin B: evidence of greater stability of α-rich domain compared to β-rich domain of the SDS derived state. Colloids Surf B Biointerfaces 2003. [DOI: 10.1016/s0927-7765(03)00160-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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20
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Shin I, Wachtel E, Roth E, Bon C, Silman I, Weiner L. Thermal denaturation of Bungarus fasciatus acetylcholinesterase: Is aggregation a driving force in protein unfolding? Protein Sci 2002; 11:2022-32. [PMID: 12142456 PMCID: PMC2373691 DOI: 10.1110/ps.0205102] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
A monomeric form of acetylcholinesterase from the venom of Bungarus fasciatus is converted to a partially unfolded molten globule species by thermal inactivation, and subsequently aggregates rapidly. To separate the kinetics of unfolding from those of aggregation, single molecules of the monomeric enzyme were encapsulated in reverse micelles of Brij 30 in 2,2,4-trimethylpentane, or in large unilamellar vesicles of egg lecithin/cholesterol at various protein/micelle (vesicle) ratios. The first-order rate constant for thermal inactivation at 45 degrees C, of single molecules entrapped within the reverse micelles (0.031 min(-1)), was higher than in aqueous solution (0.007 min(-1)) or in the presence of normal micelles (0.020 min(-1)). This clearly shows that aggregation does not provide the driving force for thermal inactivation of BfAChE. Within the large unilamellar vesicles, at average protein/vesicle ratios of 1:1 and 10:1, the first-order rate constants for thermal inactivation of the encapsulated monomeric acetylcholinesterase, at 53 degrees C, were 0.317 and 0.342 min(-1), respectively. A crosslinking technique, utilizing the photosensitive probe, hypericin, showed that thermal denaturation produces a distribution of species ranging from dimers through to large aggregates. Consequently, at a protein/vesicle ratio of 10:1, aggregation can occur upon thermal denaturation. Thus, these experiments also demonstrate that aggregation does not drive the thermal unfolding of Bungarus fasciatus acetylcholinesterase. Our experimental approach also permitted monitoring of recovery of enzymic activity after thermal denaturation in the absence of a competing aggregation process. Whereas no detectable recovery of enzymic activity could be observed in aqueous solution, up to 23% activity could be obtained for enzyme sequestered in the reverse micelles.
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Affiliation(s)
- I Shin
- Department of Neurobiology, Weizmann Institute of Science, Rehovot 76100, Israel
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21
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Krishna SH, Srinivas ND, Raghavarao KSMS, Karanth NG. Reverse micellar extraction for downstream processing of proteins/enzymes. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2002; 75:119-83. [PMID: 11787493 DOI: 10.1007/3-540-44604-4_5] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
Abstract
New developments in the area of downstream processing are, hopefully, to fulfill the promises of modern biotechnology. The traditional separation processes such as chromatography or electrophoresis can become prohibitively expensive unless the product is of high value. Hence, there is a need to develop efficient and cost-effective downstream processing methods. Reverse micellar extraction is one such potential and a promising liquid-liquid extraction technique, which has received immense attention for isolation and purification of proteins/enzymes in the recent times. This technique is easy to scale-up and offers continuous operation. This review, besides briefly considering important physico-chemical and biological aspects, highlights the engineering aspects including mass transfer, mathematical modeling, and technology development. It also discusses recent developments in reverse micellar extraction such as affinity based separations, enzymatic reactions in reverse micelles coupled with membrane processes, reverse micellar extraction in hollow fibers, etc. Special emphasis has been given to some recent applications of this technique.
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Affiliation(s)
- S Hari Krishna
- Department of Fermentation Technology & Bioengineering, Central Food Technological Research Institute, Mysore, India.
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23
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The influence of the binding of low molecular weight surfactants on the thermal stability and secondary structure of IgG. Colloids Surf A Physicochem Eng Asp 2000. [DOI: 10.1016/s0927-7757(99)00332-5] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Melo EP, Carvalho CM, Aires-Barros MR, Costa SM, Cabral JM. Deactivation and conformational changes of cutinase in reverse micelles. Biotechnol Bioeng 1998; 58:380-6. [PMID: 10099272 DOI: 10.1002/(sici)1097-0290(19980520)58:4<380::aid-bit5>3.0.co;2-f] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Deactivation data and fluorescence intensity changes were used to probe functional and structural stability of cutinase in reverse micelles. A fast deactivation of cutinase in anionic (AOT) reverse micelles occurs due to a reversible denaturation process. The deactivation and denaturation of cutinase is slower in small cationic (CTAB/1-hexanol) reverse micelles and does not occur when the size of the cationic reverse micellar water-pool is larger than cutinase. In both systems, activity loss and denaturation are coupled processes showing the same trend with time. Denaturation is probably caused by the interaction between the enzyme and the surfactant interface of the reversed micelle. When the size of the empty reversed micelle water-pool is smaller than cutinase (at W0 5, with W0 being the water:surfactant concentration ratio) a three-state model describes denaturation and deactivation with an intermediate conformational state existing on the path from native to denaturated cutinase. This intermediate was clearly detected by an increase in activity and shows only minor conformational changes relative to the native state. At W0 20, the size of the empty water-pool was larger than cutinase and the data was well described by a two-state model for both anionic and cationic reverse micelles. For AOT reverse micelles at W0 20, the intermediate state became a transient state and the deactivation and denaturation were described by a two-state model in which only native and denaturated cutinase were present. For CTAB/1-hexanol reverse micelles at W0 20, the native cutinase was in equilibrium with an intermediate state, which did not suffer denaturation. 1-Hexanol showed a stabilizing effect on cutinase in reverse micelles, contributing to the higher stabilities observed in the cationic CTAB/1-hexanol reverse micelles. Copyright 1998 John Wiley & Sons, Inc.
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Affiliation(s)
- EP Melo
- Centro de Engenharia Biologica e Quimica, Laboratorio Engenharia Bioquimica, Instituto Superior Tecnico, 1000 Lisbon, Portugal
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25
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Time-resolved fluorescence studies of ribonuclease T1 in reversed micelles. J Fluoresc 1996; 6:169-75. [PMID: 24227206 DOI: 10.1007/bf00732057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/1995] [Accepted: 07/29/1996] [Indexed: 10/26/2022]
Abstract
Time-resolved fluorescence intensity and anisotropy decay data were obtained for ribonuclease T1 entrapped in bis(2-ethylhexyl) sodium sulfosuccinate/heptane reverse micelles, as a function of the size of the inner water pool at neutral pH. Data have been presented previously to show that this protein retains its native structure and undergoes reversible thermal unfolding in these reverse micelles (Shastry and Eftink,Biochemistry 36, in press). The fluorescence decay of entrapped protein is similar to that for the protein in buffer. The rotational correlation time of entrapped ribonuclease T1 is found to be longer than that in buffer; this rotational correlation time decreases with increasing size of the water pool but is still over twice the value for the protein in buffer for the largest size of water pool investigated, indicating an increased microviscosity within the reverse micelle. Thermal unfolding of the protein results in a significant decrease in the rotational correlation time of the entrapped proteins, consistent with the protein being unfolded but not interacting with the inner surfactant wall of the reverse micelle.
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