Can a Charged Surfactant Unfold an Uncharged Protein?
Ontology highlight
ABSTRACT:
SUBMITTER: Hojgaard C
PROVIDER: S-EPMC6289093 | biostudies-literature | 2018 Dec
REPOSITORIES: biostudies-literature
Publications
Can a Charged Surfactant Unfold an Uncharged Protein?
Højgaard Casper C Sørensen Henrik Vinther HV Pedersen Jan Skov JS Winther Jakob Rahr JR Otzen Daniel Erik DE
Biophysical journal 20181115 11
Does sodium dodecyl sulfate (SDS) denature proteins through electrostatic SDS-protein interactions? We show that a protein completely lacking charged side chains is unfolded by SDS in a manner similar to charged proteins, revealing that formal protein charges are not required for SDS-induced protein unfolding or binding. ...[more]
Similar Datasets
Project description:Yanking the chain: a general method for the preparation of colloidal analogues of polymer chains was developed. The flexibility of these chains can be tuned by applying electric fields in combination with their subjection to simple linkage-forming procedures.
| S-EPMC3556699 | biostudies-literature
Project description:Parkinson's disease (PD) is the second most common neurodegenerative disorder. An important hallmark of PD involves the pathological aggregation of proteins in structures known as Lewy bodies. The major component of these proteinaceous inclusions is alpha (α)-synuclein. In different conditions, α-synuclein can assume conformations rich in either α-helix or β-sheets. The mechanisms of α-synuclein misfolding, aggregation, and fibrillation remain unknown, but it is thought that β-sheet conformation of α-synuclein is responsible for its associated toxic mechanisms. To gain fundamental insights into the process of α-synuclein misfolding and aggregation, the secondary structure of this protein in the presence of charged and non-charged surfactant solutions was characterized. The selected surfactants were (anionic) sodium dodecyl sulphate (SDS), (cationic) cetyltrimethylammonium chloride (CTAC), and (uncharged) octyl β-D-glucopyranoside (OG). The effect of surfactants in α-synuclein misfolding was assessed by ultra-structural analyses, in vitro aggregation assays, and secondary structure analyses. The α-synuclein aggregation in the presence of negatively charged SDS suggests that SDS-monomer complexes stimulate the aggregation process. A reduction in the electrostatic repulsion between N- and C-terminal and in the hydrophobic interactions between the NAC (non-amyloid beta component) region and the C-terminal seems to be important to undergo aggregation. Fourier transform infrared spectroscopy (FTIR) measurements show that β-sheet structures comprise the assembly of the fibrils.
| S-EPMC8624236 | biostudies-literature
Project description:The shape and size of self-assembled structures upon local organization of their molecular building blocks are hard to predict in the presence of long-range interactions. Combining small-angle X-ray/neutron scattering data, theoretical modelling, and computer simulations, sodium dodecyl sulfate (SDS), over a broad range of concentrations and ionic strengths, was investigated. Computer simulations indicate that micellar shape changes are associated with different binding of the counterions. By employing a toy model based on point charges on a surface, and comparing it to experiments and simulations, it is demonstrated that the observed morphological changes are caused by symmetry breaking of the irreducible building blocks, with the formation of transient surfactant dimers mediated by the counterions that promote the stabilization of cylindrical instead of spherical micelles. The present model is of general applicability and can be extended to all systems controlled by the presence of mobile charges.
| S-EPMC7589243 | biostudies-literature
Project description:The article summarizes the results of our research on the behavior of ions at uncharged fluid interfaces, with a focus on moderately to highly concentrated aqueous electrolytes. The ion-specific properties of such interfaces have been analyzed. The ion-specificity series are different for water|air and water|oil; different for surface tension σ, surface Δχ potential and electrolyte adsorption, and they change with concentration. A methodology has been developed that allows to disentangle the multiple factors controlling the ion order. The direct ion-surface interactions are not always the most significant factor behind the observed ion sequences: indirect effects stemming from conjugate bulk properties are often more important. For example, the order of the surface tension with the nature of the anion (σKOH > σKCl > σKNO3 for potassium salts) is often the result of bulk nonideality and follows the order of the bulk activity coefficients (γKOH > γKCl > γKNO3) rather than that of a specific ion-surface interaction potential. The surface Δχ potential of aqueous solutions is, in many cases, insensitive to the ion distribution in the electric double layer but reflects the orientation of water at the surface, through the ion-specific dielectric permittivity ε of the solution. Even the sign of Δχ is often the result of the decrement of ε in the presence of electrolyte. A whole new level of complexity appears when the ions interact with an uncharged surfactant monolayer. A method has been developed to measure the electrolyte adsorption isotherms on monolayers of varying area per surfactant molecule via a combination of experiments-compression isotherms and surface pressure of equilibrium spread monolayers. The obtained isotherms demonstrate that the ions exhibit a maximum in their adsorption on monolayers of intermediate density. The maximum is explained with the interplay between ion-surfactant complexation, volume exclusion and osmotic effects.
| S-EPMC11340029 | biostudies-literature
Project description:Bicontinuous particle-stabilized emulsions (bijels) are networks of interpenetrating oil/water channels with applications in catalysis, tissue engineering, and energy storage. Bijels can be generated by arresting solvent transfer induced phase separation (STrIPS) via interfacial jamming of nanoparticles. However, until now, STrIPS bijels have only been formed with silica nanoparticles of low surface charge densities, limiting their potential applications in catalysis and fluid transport. Here, we show how strongly charged silica nanoparticles can stabilize bijels. To this end, we carry out a systematic study employing dynamic light scattering, zeta potential, acid/base titrations, turbidimetry, surface tension, and confocal microscopy. We find that moderating the adsorption of oppositely charged surfactants on the particles is crucial to facilitate particle dispersibility in the bijel casting mixture and bijel stabilization. Our results potentially introduce a general understanding for bijel fabrication with different inorganic nanoparticle materials of variable charge density.
| S-EPMC7295363 | biostudies-literature
Project description:Study the Role of Surfactant Protein C in Innate Lung Defense. Gene expression profiles comparison between isolated TYPE II cells from SPC(-/-) and control litter mates.
2012-08-21 | E-GEOD-35989 | biostudies-arrayexpress
Project description:Study the Role of Surfactant Protein C in Innate Lung Defense.
2012-08-21 | GSE35989 | GEO
Project description:Dicarboxylic amino acid-based surfactants (N-dodecyl derivatives of -aminomalonate, -aspartate, and -glutamate) in combination with hexadecyltrimethylammonium bromide (HTAB) form a variety of aggregates. Composition and concentration-dependent mixtures exhibit liquid crystal, gel, precipitate, and clear isotropic phases. Liquid crystalline patterns, formed by surfactant mixtures, were identified by polarizing optical microscopy. FE-SEM studies reveal the existence of surface morphologies of different mixed aggregates. Phase transition and associated weight loss were found to depend on the composition where thermotropic behaviours were revealed through combined differential scanning calorimetry and thermogravimetric studies. Systems comprising more than 60 mol% HTAB demonstrate shear-thinning behaviour. Gels cause insignificant toxicity to human peripheral lymphocytes and irritation to bare mouse skin; they do not display the symptoms of cutaneous irritation, neutrophilic invasion, and inflammation (erythema, edema, and skin thinning) as evidenced by cumulative irritancy index score. Gels also exhibit substantial antibacterial effects on Staphylococcus aureus, a potent causative agent of skin and soft tissue infections, suggesting its possible application as a vehicle for topical dermatological drug delivery.
| S-EPMC8324821 | biostudies-literature
Project description:Mutations in the SFTPC gene associated with interstitial lung disease in human patients result in misfolding, endoplasmic reticulum (ER) retention, and degradation of the encoded surfactant protein C (SP-C) proprotein. To identify candidate genes involved in ER quality control of SP-C, HEK293 cells were transiently transfected with mutant SP-C (SP-CΔexon4 or SP-CL188Q), SP-CWT, or vector cDNAs, and global changes in gene expression were assessed by microarray analyses. Microarray analysis demonstrated that the SPC exon 4 deletion and SPC L188Q mutations invoke very similar transcriptional profiles including the activation of major players mediating ER response and unfolding protein response (UPR) in transient transfection system. In combination with promoter scan (UPRE, ERSE, XBP1 sites) and protein domain analysis (Finding ER Lumen, ER Membrane retention signal, J-Domain and Leucine Zipper domain), we were able to not only verify the known ERAD components (XBP1, Bip, Erdj4&5), but also identify multiple ER components which may play critical roles in the detection and /or degradation of mutant SPC, which in turn will help us to gain better understanding of the entire mammalian ERAD machinery. samples consisted of HEK293 cells transiently transfected with wild-type SP-C (WT), the delta exon4 mutant of SP-C (Ex4) or L188Q mutant of SP-C (LQ). Groups were performed in triplicate.
2009-05-14 | E-GEOD-16054 | biostudies-arrayexpress
Project description:AAA(+) unfoldases denature and translocate polypeptides into associated peptidases. We report direct observations of mechanical, force-induced protein unfolding by the ClpX unfoldase from E. coli, alone, and in complex with the ClpP peptidase. ClpX hydrolyzes ATP to generate mechanical force and translocate polypeptides through its central pore. Threading is interrupted by pauses that are found to be off the main translocation pathway. ClpX's translocation velocity is force dependent, reaching a maximum of 80 aa/s near-zero force and vanishing at around 20 pN. ClpX takes 1, 2, or 3 nm steps, suggesting a fundamental step-size of 1 nm and a certain degree of intersubunit coordination. When ClpX encounters a folded protein, it either overcomes this mechanical barrier or slips on the polypeptide before making another unfolding attempt. Binding of ClpP decreases the slip probability and enhances the unfolding efficiency of ClpX. Under the action of ClpXP, GFP unravels cooperatively via a transient intermediate.
| S-EPMC3686100 | biostudies-literature