151
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Vostrikov VV, Soller KJ, Ha KN, Gopinath T, Veglia G. Effects of naturally occurring arginine 14 deletion on phospholamban conformational dynamics and membrane interactions. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2014; 1848:315-22. [PMID: 25251363 DOI: 10.1016/j.bbamem.2014.09.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Revised: 09/12/2014] [Accepted: 09/13/2014] [Indexed: 01/10/2023]
Abstract
Phospholamban (PLN) is a single-pass membrane protein that regulates the sarco(endo)plasmic reticulum Ca²⁺-ATPase (SERCA). Phosphorylation of PLN at Ser16 reverses its inhibitory function under β-adrenergic stimulation, augmenting Ca²⁺ uptake in the sarcoplasmic reticulum and muscle contractility. PLN exists in two conformations; a T state, where the cytoplasmic domain is helical and adsorbed on the membrane surface, and an R state, where the cytoplasmic domain is unfolded and membrane detached. Previous studies have shown that the PLN conformational equilibrium is crucial to SERCA regulation. Here, we used a combination of solution and solid-state NMR to compare the structural topology and conformational dynamics of monomeric PLN (PLN(AFA)) with that of the PLN(R14del), a naturally occurring deletion mutant that is linked to the progression of dilated cardiomyopathy. We found that the behavior of the inhibitory transmembrane domain of PLN(R14del) is similar to that of the native sequence. Conversely, the conformational dynamics of R14del both in micelles and lipid membranes are enhanced. We conclude that the deletion of Arg14 in the cytoplasmic region weakens the interactions with the membrane and shifts the conformational equilibrium of PLN toward the disordered R state. This conformational transition is correlated with the loss-of-function character of this mutant and is corroborated by SERCA's activity assays. These findings support our hypothesis that SERCA function is fine-tuned by PLN conformational dynamics and begin to explain the aberrant regulation of SERCA by the R14del mutant.
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Affiliation(s)
- Vitaly V Vostrikov
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Kailey J Soller
- Department of Chemistry, University of Minnesota, Minneapolis, MN 55455, USA
| | - Kim N Ha
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA; Department of Chemistry and Biochemistry, St. Catherine University, St. Paul, MN 55105, USA
| | - T Gopinath
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Gianluigi Veglia
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA; Department of Chemistry, University of Minnesota, Minneapolis, MN 55455, USA.
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152
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Døvling Kaspersen J, Moestrup Jessen C, Stougaard Vad B, Skipper Sørensen E, Kleiner Andersen K, Glasius M, Pinto Oliveira CL, Otzen DE, Pedersen JS. Low-Resolution Structures of OmpA⋅DDM Protein-Detergent Complexes. Chembiochem 2014; 15:2113-24. [DOI: 10.1002/cbic.201402162] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Indexed: 11/07/2022]
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153
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Patchornik G, Wachtel E, Kesselman E, Danino D. Cryo-TEM structural analysis of conjugated nonionic engineered-micelles. SOFT MATTER 2014; 10:4922-4928. [PMID: 24874009 DOI: 10.1039/c4sm00462k] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Conjugated engineered-micelles, i.e. micelles that are composed of nonionic detergents and hydrophobic chelators and subsequently conjugated in the presence of divalent metal ions, have been shown to be remarkably suited to the task of membrane protein purification, maintaining these proteins in their native state. They also efficiently solubilize highly hydrophobic antibiotics. To date, however, the morphological changes induced in the initially spherical or ellipsoidal micelles by conjugation have not been explored. In this study, the very rapid sample-vitrification protocol of cryogenic transmission electron microscopy (cryo-TEM) has been used to capture structural transformations that engineered-micelles undergo immediately following conjugation with the [(bathophenanthroline)3:Fe(2+)] hydrophobic complex. We found that condensed thread-like aggregates are formed when the detergents used are: octyl β-D-glucopyranoside (OG), octyl β-D-thioglucopyranoside (OTG) or pentaethylene glycol monododecyl ether (C12E5). However, with β-D-maltoside (DM), n-dodecyl β-D-maltoside (DDM) or β-D-glucopyranoside (DDG), lamellar structures, some of which appear as stacked lamellae or multilamellar vesicles (MLV's), were observed. Such architectural changes occur under very mild conditions i.e. low detergent concentration, no temperature or pH alterations and without the presence of any precipitants such as PEG or ammonium sulfate.
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Affiliation(s)
- Guy Patchornik
- Department of Biological Chemistry, Ariel University, 70400, Israel.
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154
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Sikorska E, Dawgul M, Greber K, Iłowska E, Pogorzelska A, Kamysz W. Self-assembly and interactions of short antimicrobial cationic lipopeptides with membrane lipids: ITC, FTIR and molecular dynamics studies. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2014; 1838:2625-34. [PMID: 24978107 DOI: 10.1016/j.bbamem.2014.06.016] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2014] [Revised: 05/13/2014] [Accepted: 06/23/2014] [Indexed: 11/28/2022]
Abstract
In this work, the self-organization and the behavior of the surfactant-like peptides in the presence of biological membrane models were studied. The studies were focused on synthetic palmitic acid-containing lipopeptides, C16-KK-NH2 (I), C16-KGK-NH2 (II) and C16-KKKK-NH2 (III). The self-assembly was explored by molecular dynamics simulations using a coarse-grained force field. The critical micellar concentration was estimated by the surface tension measurements. The thermodynamics of the peptides binding to the anionic and zwitterionic lipids were established using isothermal titration calorimetry (ITC). The influence of the peptides on the lipid acyl chain ordering was determined using FTIR spectroscopy. The compounds studied show surface-active properties with a distinct CMC over the millimolar range. An increase in the steric and electrostatic repulsion between polar head groups shifts the CMC toward higher values and reduces the aggregation number. An analysis of the peptide-membrane binding revealed a unique interplay between the initial electrostatic and the subsequent hydrophobic interactions enabling the lipopeptides to interact with the lipid bilayer. In the case of C16-KKKK-NH2 (III), compensation of the electrostatic and hydrophobic interactions upon binding to the anionic membrane has been suggested and consequently no overall binding effects were noticed in ITC thermograms and FTIR spectra.
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Affiliation(s)
- Emilia Sikorska
- Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308 Gdańsk, Poland.
| | - Małgorzata Dawgul
- Faculty of Pharmacy with Subfaculty of Laboratory Medicine, Medical University of Gdańsk, Al. Gen. J. Hallera 107, 80-416 Gdańsk, Poland
| | - Katarzyna Greber
- Faculty of Pharmacy with Subfaculty of Laboratory Medicine, Medical University of Gdańsk, Al. Gen. J. Hallera 107, 80-416 Gdańsk, Poland
| | - Emilia Iłowska
- Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308 Gdańsk, Poland
| | - Aneta Pogorzelska
- Faculty of Pharmacy with Subfaculty of Laboratory Medicine, Medical University of Gdańsk, Al. Gen. J. Hallera 107, 80-416 Gdańsk, Poland
| | - Wojciech Kamysz
- Faculty of Pharmacy with Subfaculty of Laboratory Medicine, Medical University of Gdańsk, Al. Gen. J. Hallera 107, 80-416 Gdańsk, Poland
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155
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Pernstich C, Senior L, MacInnes KA, Forsaith M, Curnow P. Expression, purification and reconstitution of the 4-hydroxybenzoate transporter PcaK from Acinetobacter sp. ADP1. Protein Expr Purif 2014; 101:68-75. [PMID: 24907408 PMCID: PMC4148202 DOI: 10.1016/j.pep.2014.05.011] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Revised: 05/20/2014] [Accepted: 05/23/2014] [Indexed: 11/19/2022]
Abstract
The aromatic acid transporter PcaK was recombinantly expressed and purified. PcaK is a stable homotrimer in n-dodecyl-β-d-maltoside. A reconstituted assay shows asymmetric transport. The electrical component of the proton gradient drives transport. Unexpectedly, PcaK is active in transporting 2-hydroxybenzoates.
The aromatic acid:H+ symporter family of integral membrane proteins play an important role in the microbial metabolism of aromatic compounds. Here, we show that the 4-hydroxybenzoate transporter from Acinetobacter sp. ADP1, PcaK, can be successfully overexpressed in Escherichia coli and purified by affinity chromatography. Affinity-purified PcaK is a stable, monodisperse homotrimer in the detergent n-dodecyl-β-d-maltopyranoside supplemented with cholesteryl hemisuccinate. The purified protein has α-helical secondary structure and can be reconstituted to a functional state in synthetic proteoliposomes. Asymmetric substrate transport was observed when proteoliposomes were energized by applying an electrochemical proton gradient (Δμ‾H+) or a membrane potential (ΔΨ) but not by ΔpH alone. PcaK was selective in transporting 4-hydroxybenzoate and 3,4-dihydroxybenzoate over closely related compounds, confirming previous reports on substrate specificity. However, PcaK also showed an unexpected preference for transporting 2-hydroxybenzoates. These results provide the basis for further detailed studies of the structure and function of this family of transporters.
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Affiliation(s)
| | - Laura Senior
- School of Biochemistry, University of Bristol, Bristol BS8 1TD, UK; Bristol Centre for Functional Nanomaterials, University of Bristol, Bristol BS8 1TD, UK
| | | | - Marc Forsaith
- School of Biochemistry, University of Bristol, Bristol BS8 1TD, UK
| | - Paul Curnow
- School of Biochemistry, University of Bristol, Bristol BS8 1TD, UK.
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156
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Murray D, Griffin J, Cross TA. Detergent optimized membrane protein reconstitution in liposomes for solid state NMR. Biochemistry 2014; 53:2454-63. [PMID: 24665863 PMCID: PMC4004220 DOI: 10.1021/bi500144h] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2014] [Revised: 03/24/2014] [Indexed: 12/18/2022]
Abstract
For small helical membrane proteins, their structures are highly sensitive to their environment, and solid state NMR is a structural technique that can characterize these membrane proteins in native-like lipid bilayers and proteoliposomes. To date, a systematic method by which to evaluate the effect of the solubilizing detergent on proteoliposome preparations for solid state NMR of membrane proteins has not been presented in the literature. A set of experiments are presented aimed at determining the conditions most amenable to dialysis mediated reconstitution sample preparation. A membrane protein from M. tuberculosis is used to illustrate the method. The results show that a detergent that stabilizes the most protein is not always ideal and sometimes cannot be removed by dialysis. By focusing on the lipid and protein binding properties of the detergent, proteoliposome preparations can be readily produced, which provide double the signal-to-noise ratios for both the oriented sample and magic angle spinning solid state NMR. The method will allow more membrane protein drug targets to be structurally characterized in lipid bilayer environments.
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Affiliation(s)
- Dylan
T. Murray
- Institute
for Molecular Biophysics, Florida State
University, 91 Chieftan
Way, Tallahassee, Florida 32306, United States
- The
National High Magnetic Field Laboratory, 1800 E. Paul Dirac Dr., Tallahassee, Florida 32310, United States
| | - James Griffin
- The
National High Magnetic Field Laboratory, 1800 E. Paul Dirac Dr., Tallahassee, Florida 32310, United States
- Department
of Chemistry and Biochemistry, Florida State
University, 95 Chieftan
Way, Tallahassee, Florida 32306, United States
| | - Timothy A. Cross
- Institute
for Molecular Biophysics, Florida State
University, 91 Chieftan
Way, Tallahassee, Florida 32306, United States
- The
National High Magnetic Field Laboratory, 1800 E. Paul Dirac Dr., Tallahassee, Florida 32310, United States
- Department
of Chemistry and Biochemistry, Florida State
University, 95 Chieftan
Way, Tallahassee, Florida 32306, United States
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157
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Ilgü H, Jeckelmann JM, Gachet MS, Boggavarapu R, Ucurum Z, Gertsch J, Fotiadis D. Variation of the detergent-binding capacity and phospholipid content of membrane proteins when purified in different detergents. Biophys J 2014; 106:1660-70. [PMID: 24739165 PMCID: PMC4008799 DOI: 10.1016/j.bpj.2014.02.024] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2013] [Revised: 02/21/2014] [Accepted: 02/26/2014] [Indexed: 11/24/2022] Open
Abstract
Purified membrane proteins are ternary complexes consisting of protein, lipid, and detergent. Information about the amounts of detergent and endogenous phospholipid molecules bound to purified membrane proteins is largely lacking. In this systematic study, three model membrane proteins of different oligomeric states were purified in nine different detergents at commonly used concentrations and characterized biochemically and biophysically. Detergent-binding capacities and phospholipid contents of the model proteins were determined and compared. The insights on ternary complexes obtained from the experimental results, when put into a general context, are summarized as follows. 1), The amount of detergent and 2) the amount of endogenous phospholipids bound to purified membrane proteins are dependent on the size of the hydrophobic lipid-accessible protein surface areas and the physicochemical properties of the detergents used. 3), The size of the detergent and lipid belt surrounding the hydrophobic lipid-accessible surface of purified membrane proteins can be tuned by the appropriate choice of detergent. 4), The detergents n-nonyl-β-D-glucopyranoside and Cymal-5 have exceptional delipidating effects on ternary complexes. 5), The types of endogenous phospholipids bound to membrane proteins can vary depending on the detergent used for solubilization and purification. 6), Furthermore, we demonstrate that size-exclusion chromatography can be a suitable method for estimating the molecular mass of ternary complexes. The findings presented suggest a strategy to control and tune the numbers of detergent and endogenous phospholipid molecules bound to membrane proteins. These two parameters are potentially important for the successul crystallization of membrane proteins for structure determination by crystallographic approaches.
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Affiliation(s)
- Hüseyin Ilgü
- Institute of Biochemistry and Molecular Medicine, and Swiss National Centre of Competence in Research (NCCR) TransCure, University of Bern, Bern, Switzerland
| | - Jean-Marc Jeckelmann
- Institute of Biochemistry and Molecular Medicine, and Swiss National Centre of Competence in Research (NCCR) TransCure, University of Bern, Bern, Switzerland
| | - María Salomé Gachet
- Institute of Biochemistry and Molecular Medicine, and Swiss National Centre of Competence in Research (NCCR) TransCure, University of Bern, Bern, Switzerland
| | - Rajendra Boggavarapu
- Institute of Biochemistry and Molecular Medicine, and Swiss National Centre of Competence in Research (NCCR) TransCure, University of Bern, Bern, Switzerland
| | - Zöhre Ucurum
- Institute of Biochemistry and Molecular Medicine, and Swiss National Centre of Competence in Research (NCCR) TransCure, University of Bern, Bern, Switzerland
| | - Jürg Gertsch
- Institute of Biochemistry and Molecular Medicine, and Swiss National Centre of Competence in Research (NCCR) TransCure, University of Bern, Bern, Switzerland
| | - Dimitrios Fotiadis
- Institute of Biochemistry and Molecular Medicine, and Swiss National Centre of Competence in Research (NCCR) TransCure, University of Bern, Bern, Switzerland.
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158
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Martin-Garcia JM, Hansen DT, Zook J, Loskutov AV, Robida MD, Craciunescu FM, Sykes KF, Wachter RM, Fromme P, Allen JP. Purification and biophysical characterization of the CapA membrane protein FTT0807 from Francisella tularensis. Biochemistry 2014; 53:1958-70. [PMID: 24593131 PMCID: PMC3985703 DOI: 10.1021/bi401644s] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
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The capA gene (FTT0807)
from Francisella
tularensis subsp. tularensis SCHU S4 encodes a 44.4
kDa integral membrane protein composed of 403 amino acid residues
that is part of an apparent operon that encodes at least two other
membrane proteins, CapB, and CapC, which together play a critical
role in the virulence and pathogenesis of this bacterium. The capA gene was overexpressed in Escherichia
coli as a C-terminal His6-tagged fusion
with a folding reporter green fluorescent protein (frGFP). Purification
procedures using several detergents were developed for the fluorescing
and membrane-bound product, yielding approximately 30 mg of pure protein
per liter of bacterial culture. Dynamic light scattering indicated
that CapA-frGFP was highly monodisperse, with a size that was dependent
upon both the concentration and choice of detergent. Circular dichroism
showed that CapA-frGFP was stable over the range of 3–9 for
the pH, with approximately half of the protein having well-defined
α-helical and β-sheet secondary structure. The addition
of either sodium chloride or calcium chloride at concentrations producing
ionic strengths above 0.1 M resulted in a small increase of the α-helical
content and a corresponding decrease in the random-coil content. Secondary-structure
predictions on the basis of the analysis of the sequence indicate
that the CapA membrane protein has two transmembrane helices with
a substantial hydrophilic domain. The hydrophilic domain is predicted
to contain a long disordered region of 50–60 residues, suggesting
that the increase of α-helical content at high ionic strength
could arise because of electrostatic interactions involving the disordered
region. CapA is shown to be an inner-membrane protein and is predicted
to play a key cellular role in the assembly of polysaccharides.
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Affiliation(s)
- Jose M Martin-Garcia
- Department of Chemistry and Biochemistry, Arizona State University , Tempe, Arizona 85287, United States
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159
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L. Pollock N, Moran O, Baroni D, Zegarra-Moran O, C. Ford R. Characterisation of the salmon cystic fibrosis transmembrane conductance regulator protein for structural studies. AIMS MOLECULAR SCIENCE 2014. [DOI: 10.3934/molsci.2014.4.141] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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160
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López-Castilla A, Pazos F, Schreier S, Pires JR. Solution NMR analysis of the interaction between the actinoporin sticholysin I and DHPC micelles--correlation with backbone dynamics. Proteins 2013; 82:1022-34. [PMID: 24218049 DOI: 10.1002/prot.24475] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Revised: 10/26/2013] [Accepted: 11/04/2013] [Indexed: 11/08/2022]
Abstract
Sticholysin I (StI), an actinoporin expressed as a water-soluble protein by the sea anemone Stichodactyla helianthus, binds to natural and model membranes, forming oligomeric pores. It is proposed that the first event of a multistep pore formation mechanism consists of the monomeric protein attachment to the lipid bilayer. To date there is no high-resolution structure of the actinoporin pore or other membrane-bound form available. Here we evaluated StI:micelle complexes of variable lipid composition to look for a suitable model for NMR studies. Micelles of pure or mixed lysophospholipids and of dihexanoyl phosphatidylcholine (DHPC) were examined. The StI:DHPC micelle was found to be the best system, yielding a stable sample and good quality spectra. A comprehensive chemical shift perturbation analysis was performed to map the StI membrane recognition site in the presence of DHPC micelles. The region mapped (residues F(51), R(52), S(53) in loop 3; F(107), D(108), Y(109), W(111), Y(112), W(115) in loop 7; Q(129), Y(132), D(134), M(135), Y(136), Y(137), G(138) in helix-α2) is in agreement with previously reported data, but additional residues were found to interact, especially residues V(81), A(82), T(83), G(84) in loop 5, and A(85), A(87) in strand-β5. Backbone dynamics measurements of StI free in solution and bound to micelles highlighted the relevance of protein flexibility for membrane binding and suggested that a conformer selection process may take place during protein-membrane interaction. We conclude that the StI:DHPC micelles system is a suitable model for further characterization of an actinoporin membrane-bound form by solution NMR.
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Affiliation(s)
- Aracelys López-Castilla
- Centro de Estudio de Proteinas, Facultad de Biologia, Universidad de la Habana, Habana, Cuba; Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, RJ, Brazil
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161
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Broecker J, Keller S. Impact of urea on detergent micelle properties. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:8502-8510. [PMID: 23745835 DOI: 10.1021/la4013747] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Co-solvents, such as urea, can entail drastic changes in the micellization behavior of detergents. We present a systematic quantification of the impact of urea on the critical micellar concentration, the micellization thermodynamics, and the micelle size in three homologous series of commonly used non-ionic alkyl detergents. To this end, we performed demicellization experiments by isothermal titration calorimetry and hydrodynamic size measurements by dynamic light scattering on alkyl maltopyranosides, cyclohexyl alkyl maltopyranosides, and alkyl glucopyranosides at urea concentrations of 0-8 M. For all detergents studied, we found that the critical micellar concentration increases exponentially because the absolute Gibbs free energy of micellization decreases linearly over the entire urea concentration range, as does the micelle size. In contrast, the enthalpic and entropic contributions to micellization reveal more complex, nonlinear dependences on urea concentration. Both free energy and size changes are more pronounced for long-chain detergents, which bury more apolar surface area upon micelle formation. The Gibbs free energy increments per methylene group within each detergent series depend on urea concentration in a linear fashion, although they result from the entropic term for alkyl maltosides but are of enthalpic origin for cyclohexyl alkyl maltosides. We compare our results to transfer free energies of amino acid side chains, relate them to protein-folding data, and discuss how urea-induced changes in detergent micelle properties affect in vitro investigations on membrane proteins.
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Affiliation(s)
- Jana Broecker
- Molecular Biophysics, University of Kaiserslautern, Erwin-Schrödinger-Strasse 13, 67663 Kaiserslautern, Germany
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