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1.
Celina Love Jan Steinkühler David T. Gonzales Naresh Yandrapalli Tom Robinson Rumiana Dimova T.‐Y. Dora Tang 《Angewandte Chemie (International ed. in English)》2020,59(15):5950-5957
In situ, reversible coacervate formation within lipid vesicles represents a key step in the development of responsive synthetic cellular models. Herein, we exploit the pH responsiveness of a polycation above and below its pKa, to drive liquid–liquid phase separation, to form single coacervate droplets within lipid vesicles. The process is completely reversible as coacervate droplets can be disassembled by increasing the pH above the pKa. We further show that pH‐triggered coacervation in the presence of low concentrations of enzymes activates dormant enzyme reactions by increasing the local concentration within the coacervate droplets and changing the local environment around the enzyme. In conclusion, this work establishes a tunable, pH responsive, enzymatically active multi‐compartment synthetic cell. The system is readily transferred into microfluidics, making it a robust model for addressing general questions in biology, such as the role of phase separation and its effect on enzymatic reactions using a bottom‐up synthetic biology approach. 相似文献
2.
Membraneless organelles are phase-separated droplets that are dynamically assembled and dissolved in response to biochemical reactions in cells. Complex coacervate droplets produced by associative liquid–liquid phase separation offer a promising approach to mimic such dynamic compartmentalization. Here, we present a model for membraneless organelles based on enzyme/polyelectrolyte complex coacervates able to induce their own condensation and dissolution. We show that glucose oxidase forms coacervate droplets with a cationic polysaccharide on a narrow pH range, so that enzyme-driven monotonic pH changes regulate the emergence, growth, decay and dissolution of the droplets depending on the substrate concentration. Significantly, we demonstrate that time-programmed coacervate assembly and dissolution can be achieved in a single-enzyme system. We further exploit this self-driven enzyme phase separation to produce multiphase droplets via dynamic polyion self-sorting in the presence of a secondary coacervate phase. Taken together, our results open perspectives for the realization of programmable synthetic membraneless organelles based on self-regulated enzyme/polyelectrolyte complex coacervation.Self-programmed enzyme phase separation is exploited to assemble dynamic multiphase coacervate droplets via spontaneous polyion self-sorting under non-equilibrium conditions. 相似文献
3.
Nicolas Martin Liangfei Tian Dan Spencer Anglique Coutable‐Pennarun J. L. Ross Anderson Stephen Mann 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(41):14736-14740
Coacervate microdroplets produced by liquid–liquid phase separation have been used as synthetic protocells that mimic the dynamical organization of membrane‐free organelles in living systems. Achieving spatiotemporal control over droplet condensation and disassembly remains challenging. Herein, we describe the formation and photoswitchable behavior of light‐responsive coacervate droplets prepared from mixtures of double‐stranded DNA and an azobenzene cation. The droplets disassemble and reassemble under UV and blue light, respectively, due to azobenzene trans/cis photoisomerisation. Sequestration and release of captured oligonucleotides follow the dynamics of phase separation such that light‐activated transfer, mixing, hybridization, and trafficking of the oligonucleotides can be controlled in binary populations of the droplets. Our results open perspectives for the spatiotemporal control of DNA coacervates and provide a step towards the dynamic regulation of synthetic protocells. 相似文献
4.
Cells organize their interior through membrane-bound organelles and through membraneless condensates that are formed by liquid–liquid phase separation (LLPS). The complex process of coacervation that is involved in LLPS is challenging to study in living cells. Hence, studying coacervation in cell-mimicking synthetic containers can yield valuable insights. Here, we review recent progress with respect to studying LLPS (particularly coacervation) in artificial compartments, from water-in-oil droplets to membranous liposomes. We describe different strategies to form and control coacervates in microconfinements and to study their physicochemical and biological characteristics. We also describe how coacervation can itself be used in container formation. This review highlights the importance of in vitro coacervate studies for understanding cellular biology and for designing synthetic cells. 相似文献
5.
Many intrinsically disordered peptides have been shown to undergo liquid–liquid phase separation and form complex coacervates, which play various regulatory roles in the cell. Recent experimental studies found that such phase separation processes may also occur at the lipid membrane surface and help organize biomolecules during signaling events; in some cases, phase separation of proteins at the membrane surface was also observed to lead to significant remodeling of the membrane morphology. The molecular mechanisms that govern the interactions between complex coacervates and lipid membranes and the impacts of such interactions on their structure and morphology, however, remain unclear. Here we study the coacervation of poly-glutamate (E30) and poly-lysine (K30) in the presence of lipid bilayers of different compositions. We carry out explicit-solvent coarse-grained molecular dynamics simulations by using the MARTINI (v3.0) force-field. We find that more than 20% anionic lipids are required for the coacervate to form stable contact with the bilayer. Upon wetting, the coacervate induces negative curvature to the bilayer and facilitates local lipid demixing, without any peptide insertion. The magnitude of negative curvature, extent of lipid demixing, and asphericity of the coacervate increase with the concentration of anionic lipids. Overall, we observe a decrease in the number of contacts among the polyelectrolytes as the droplet spreads over the bilayer. Therefore, unlike previous suggestions, interactions among polyelectrolytes do not constitute a driving force for the membrane bending upon wetting by the coacervate. Rather, analysis of interaction energy components suggests that bending of the membrane is favored by enhanced interactions between polyelectrolytes with lipids as well as with counterions. Kinetic studies reveal that, at the studied polyelectrolyte concentrations, the coacervate formation precedes bilayer wetting.Intrinsically disordered polyelectrolytes undergoing liquid–liquid phase separation to form complex coacervates on a membrane, which profoundly alters the membrane morphology. 相似文献
6.
Syuuhei Komatsu Hidenari Kayano Yu Ando Taka-Aki Asoh Ryo Ishihara Akihiko Kikuchi 《Journal of polymer science. Part A, Polymer chemistry》2018,56(23):2623-2629
We herein report the preparation of thermo- and redox-responsive branched polymers by the condensation reaction of three-armed oligo(ethylene glycol) (trisOEG) and cystamine (CA). The prepared branched polymers exhibited a soluble–insoluble transition at a lower critical solution temperature (LCST) and formed coacervate droplets through a liquid–liquid phase separation process. We then demonstrated control of the LCSTs of the branched polymers by varying the feed ratio of CA and the surrounding salt concentration close to body temperature. In addition, the trisOEG-cys x polymer formed coacervate droplets above the LCST, in which hydrophobic molecules were condensed. The redox response of the branched polymers was also investigated. Interestingly, the branched polymers degraded to low-molecular-weight materials (i.e., trisOEG) in the presence of dithiothereitol as a reducing agent through cleavage of the disulfide bond of CA. This facile preparation of branched polymers is expected to be valuable in the context of functional biomedical materials and modifiers for materials surfaces, such as the bases for drug delivery carriers and separation materials. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 2623–2629 相似文献
7.
Three-phase interactions and interfacial transport phenomena in coacervate/oil/water systems 总被引:1,自引:0,他引:1
Complex coacervation is an associative liquid/liquid phase separation resulting in the formation of two liquid phases: a polymer-rich coacervate phase and a dilute continuous solvent phase. In the presence of a third liquid phase in the form of disperse oil droplets, the coacervate phase tends to wet the oil/water interface. This affinity has long been known and used for the formation of core/shell capsules. However, while encapsulation by simple or complex coacervation has been used empirically for decades, there is a lack of a thorough understanding of the three-phase wetting phenomena that control the formation of encapsulated, compound droplets and the role of the viscoelasticity of the biopolymers involved. In this contribution, we review and discuss the interplay of wetting phenomena and fluid viscoelasticity in coacervate/oil/water systems from the perspective of colloid chemistry and fluid dynamics, focusing on aspects of rheology, interfacial tension measurements at the coacervate/solvent interface, and on the formation and fragmentation of three-phase compound drops. 相似文献
8.
In our continuing efforts into designing boronic acid-based sensors that recognize cell-surface carbohydrates, it has been necessary to examine various factors that affect the binding affinity between a boronic acid moiety and a diol. The current prevailing view is that the strongest boronic acid/diol complexes are generated by a combination of high solution pH and a low boronic acid pKa. However, there has never been a systematic examination of the relationship among the binding constants, boronic acid pKa, and the pH of the solution. Herein we report our findings with a series of 25 arylboronic acids with various substituents and their binding affinities with diols. We have found that (1) the relationship between the pKa of monosubstituted phenylboronic acid and its substituents can be described using a Hammet plot; (2) the optimal pH for binding is not always above the pKa of the boronic acid, and is affected by the pKa values of the boronic acid and the diol, and other unknown factors; and (3) the general belief that boronic acids with lower pKa values show greater binding affinities for diols is not always true. 相似文献
9.
Hang Zhao Vusala Ibrahimova Elisabeth Garanger Sbastien Lecommandoux 《Angewandte Chemie (International ed. in English)》2020,59(27):11028-11036
Elastin‐like polypeptides (ELPs) have been proposed as a simple model of intrinsically disordered proteins (IDPs) which can form membraneless organelles by liquid–liquid phase separation (LLPS) in cells. Herein, the behavior of fluorescently labeled ELP is studied in cytomimetic aqueous two‐phase system (ATPS) encapsulated protocells that are formed using microfluidics, which enabled confinement, changes in temperature, and statistical analysis. The spatial organization of ELP could be observed in the ATPS. Furthermore, changes in temperature triggered the dynamic formation and distribution of ELP‐rich droplets within the ATPS, resulting from changes in conformation. Proteins were encapsulated along with ELP in the synthetic protocells and distinct partitioning properties of these proteins and ELP in the ATPS were observed. Therefore, the ability of ELP to coacervate with temperature can be maintained inside a cell‐mimicking system. 相似文献
10.
Ioana Diaconu Hassan Y. Aboul-Enein Mohammed A. Al-Omar Gheorghe Nechifor Elena Ruse Andrei A. Bunaciu Eugenia Eftimie Totu 《Arabian Journal of Chemistry》2011,4(1):99-103
The paper presents experimental data obtained in the study of liquid–liquid partition equilibriums in biphasic system in order to optimize the process of transport through bulk liquid membranes (triphasic partition systems). The partition equilibriums of some nitrophenols using chloroform as extraction solvent and membranary solvent, respectively, were studied. The influence of the pH on the partition equilibriums was investigated. The repartition constants and the pKa values of the studied nitrophenols were calculated. Nitrophenols were transferred in triphasic system from a feed phase with pH 2, through a chloroform liquid membrane, into a receiving phase with pH 12, with efficiencies over 90%. 相似文献
11.
Sequestration of Proteins by Fatty Acid Coacervates for Their Encapsulation within Vesicles
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David Garenne Dr. Laure Beven Dr. Laurence Navailles Prof. Frédéric Nallet Dr. Erick J. Dufourc Dr. Jean‐Paul Douliez 《Angewandte Chemie (International ed. in English)》2016,55(43):13475-13479
Encapsulating biological materials in lipid vesicles is of interest for mimicking cells; however, except in some particular cases, such processes do not occur spontaneously. Herein, we developed a simple and robust method for encapsulating proteins in fatty acid vesicles in high yields. Fatty acid based, membrane‐free coacervates spontaneously sequester proteins and can reversibly form membranous vesicles upon varying the pH value, the precrowding feature in coacervates allowing for protein encapsulation within vesicles. We then produced enzyme‐enriched vesicles and show that enzymatic reactions can occur in these micrometric capsules. This work could be of interest in the field of synthetic biology for building microreactors. 相似文献
12.
This review highlights the basis of gradient reversed-phase high-performance liquid chromatography (RP-HPLC) of ionogenic analytes.We describe pH-gradient RP-HPLC in strict theoretical terms, with examples of experiments to provide improvements in analyte separations and peak shapes, and an original method of pKa determination.Finally, we present the concept of the combined pH/organic-modifier gradient mode of RP-HPLC and illustrate it with applications. It allows optimization of separation of ionogenic analytes, along with a method for determining their biorelevant physico-chemical parameters [e.g., hydrophobicity (log kw) and acidity (pKa)]. The method is applicable to drugs and other xenobiotic mixtures, including individual analytes of interest assayed in biological fluids. 相似文献
13.
《液相色谱法及相关技术杂志》2012,35(8):1323-1338
Abstract This report describes the use of different carboxylic acids as mobile phase modifiers. The effect on retention of acid chain length, pH, and eluent composition for a series of phenylalkanols, phenol, and the amines aniline, N-methylaniline, and benzylamine is discussed. The retention of both neutral and positively charged compounds is influenced by the dissociation equilibrium of the carboxylic acid in the mobile phase. By using l-pentanol to coat excess exposed silanol groups on the reversed phase column used, the inflection in the retention of both neutral and charged solutes as pH is changed occurs at the pKa of the acid in the mobile phase. In addition, by using an acid and amine with the same or similar pKa values, selective ion-pairing of this pair over others with dissimilar pKa values can be promoted. Application of this technique to the selective retention of amino acids and peptides was unsuccessful. 相似文献
14.
Kharlamova A DeMuth JC McLuckey SA 《Journal of the American Society for Mass Spectrometry》2012,23(1):88-101
The exposure of electrospray droplets generated from either highly acidic or highly basic solutions to basic or acidic vapors,
respectively, admitted into the counter-current drying gas, has been shown to lead to significant changes in the observed
charge state distributions of proteins. In both cases, distributions of charge states changed from relatively high charge
states, indicative of largely denatured proteins, to lower charge state distributions that are more consistent with native
protein conformations. Ubiquitin, cytochrome c, myoglobin, and carbonic anhydrase were used as model systems. In some cases, bimodal distributions were observed that are
not noted under any solution pH conditions. The extent to which changes in charge state distributions occur depends upon the
initial solution pH and the pKa or pKb of the acidic or basic reagent, respectively. The evolution of charged droplets in the sampling region of the mass spectrometer
inlet aperture, where the vapor exposure takes place, occurs within roughly 1 ms. The observed changes in the spectra, therefore,
are a function of the magnitude of the pH change as well as the rates at which the proteins can respond to this change. The
exposure of electrospray droplets in this fashion may provide means for accessing transient folding states for further characterization
by mass spectrometry. 相似文献
15.
Preparation of ureido group bearing polymers and their upper critical solution temperature in water
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Ami Fujihara Kohei Itsuki Naohiko Shimada Atsushi Maruyama Naoya Sagawa Toshiyuki Shikata Shin‐Ichi Yusa 《Journal of polymer science. Part A, Polymer chemistry》2016,54(18):2845-2854
Poly(2‐ureidoethylmethacrylate) (PUEMn) was synthesized via reversible addition‐fragmentation chain transfer (RAFT) radical polymerization and following polymer reaction. We prepared two PUEMn samples with different degrees of polymerization (n = 100 and 49). The polymers exhibited upper critical solution temperature (UCST) in phosphate‐buffered saline (PBS) solution. The phase separation temperature (Tp) in PBS can be controlled ranging from 17 to 55 °C by changing molecular weight of the polymer, polymer concentration, and adding NaCl concentration. The polymers in PBS formed coacervate drops by liquid–liquid phase separations below Tp. Results of the dielectric relaxation measurement, the hydration number per monomeric unit was 5 above Tp. Based on a fluorescence study, the polymer formed slightly hydrophobic environments below Tp. The liquid–liquid phase separation was occurred presumably because of weak hydrophobic interactions and intermolecularly hydrogen bonding interactions between the pendant ureido groups. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 2845–2854 相似文献
16.
Dr. Qingchuan Li Qingchun Song Dr. Wei Guo Yang Cao Dr. Xinyu Cui Prof. Dairong Chen Prof. Ho Cheung Shum 《Angewandte Chemie (International ed. in English)》2023,62(45):e202313096
In eukaryotic cells, the membraneless organelles (MLOs) formed via liquid-liquid phase separation (LLPS) are found to interact intimately with membranous organelles (MOs). One major mode is the clustering of MOs by MLOs, such as the formation of clusters of synaptic vesicles at nerve terminals mediated by the synapsin-rich MLOs. Aqueous droplets, including complex coacervates and aqueous two-phase systems, have been plausible MLO-mimics to emulate or elucidate biological processes. However, neither of them can cluster lipid vesicles (LVs) like MLOs. In this work, we develop a synthetic droplet assembled from a combination of two different interactions underlying the formation of these two droplets, namely, associative and segregative interactions, which we call segregative-associative (SA) droplets. The SA droplets cluster and disperse LVs recapitulating the key functional features of synapsin condensates, which can be attributed to the weak electrostatic interaction environment provided by SA droplets. This work suggests LLPS with combined segregative and associative interactions as a possible route for synaptic clustering of lipid vesicles and highlights SA droplets as plausible MLO-mimics and models for studying and mimicking related cellular dynamics. 相似文献
17.
We have carried out a kinetic study of the 4-pyridinecarboxaldehyde plus n-hexylamine system, at 25°C, in water-dioxan mixtures (0–60% v/v) and in the pH range pKa + 1.5 > pH > pKa ? 1.5, where pKa is the pK value of the conjugate acid of the amine. The results obtained could be interpreted in terms of a rate constant for Schiff's base hydrolysis and a rate constant for the reaction between the nonprotonated n-hexylamine and the nonhydrated form of 4-pyridinecarboxaldehyde. Both constants decrease sharply as the dioxan content of the solvent increases, in a manner consistent with Marshall's model [J. Phys. Chem., 74 , 346 (1970)]. It is suggested that the transition state of the rate-limiting step (carbinolamine dehydration) is highly solvated by water molecules and has a high separation of charges. 相似文献
18.
OH radical reactions with ethanolamine, diethanolamine and triethanolamine were studied at pH values below and above the pKa values of these compounds. The rate constants were found to be lower for the protonated amines than those for their neutral forms. The OH radical reaction led to the formation of both oxidizing, as well as reducing species, as observed by their reactions with methyl viologen and ascorbic acid. The oxidizing species formed by OH radical reaction at the amine site was not found to react with the parent molecules and thereby no secondary yield of reducing species was obtained, as in the case of glycine (except in the case of triethanolamine at pH 9.2). 相似文献
19.
20.
Multimode Retention Behavior of Azaarenes in Size Exclusion Chromatography with Poly(Divinylbenzene)
《Analytical letters》2012,45(2):493-506
Abstract The size exclusion retention behavior of azaarenes on poly(divinylbenzene) is described. With dichloromethane as the mobile phase a strong nonsize effect was evident and retention was found to be governed by the pKa of the eluate. By changing the mobile phase to N-methylpyrrolidinone, retention became independent of pKa and components eluted in order of decreasing molecular weight. Some degree of nonsize behavior was still evident and separation proceeded through a multimode mechanism. LogMW for both the azaarenes and PAH. However, in the case of the azaarenes, a less than ideal correlation coefficient (-.705) suggests that retention is not purely size-dependent. 相似文献