27 results on '"Jiménez-Ángeles F"'
Search Results
2. The effect of confinement on the interaction between two like-charged rods
- Author
-
Odriozola, G., Jiménez-Ángeles, F., and Lozada-Cassou, M.
- Subjects
Condensed Matter - Mesoscale and Nanoscale Physics - Abstract
Monte Carlo simulations were employed to study two charged rods confined between two unlike charged plates, all immersed in a model electrolyte. Recently, it was shown that two rods immersed in a multivalent counterion solution may show attraction (PRL 78, 2477 (1997)). Here we show for a monovalent electrolyte that rod-rod attraction and repulsion can switch sign depending on confinement and ionic size. We also propose a simple self-assembling mechanism which may be helpful to understand the DNA-lipid bilayers complexation.
- Published
- 2010
- Full Text
- View/download PDF
3. Two rods confined by positive plates: Effective forces and charge distribution profiles
- Author
-
Odriozola, G., Jiménez-Ángeles, F., and Lozada-Cassou, M.
- Subjects
Condensed Matter - Mesoscale and Nanoscale Physics - Abstract
Monte Carlo simulations were employed to study two negative rods confined between two parallel plates. The system is immersed in a 1-1 restricted primitive model electrolyte. Ion distributions and forces per unit of area (pressures) on rods and plates are accessed by sampling the NVT ensemble. Pressures are analyzed by means of their corresponding electric and contact (depletion) contributions. This was done for several charge distributions on plates, plates charge densities, and plate-plate surface separation distances. We found an enhancement of the inherent repulsive rod-rod effective force when uncharged plates are the confining species. On the contrary, a strong decrease of the rod-rod effective repulsion was obtained for positively charged plates. Moreover, attraction was also found for plates having a charge equal to that of fully charged bilipid bilayers. These results agree with DNA-phospholipid complexation experiments. On the other hand, for a model having the plates charges fixed on a grid, very long range rod-rod sin-like effective forces were obtained. As explained in the text, they are a consequence of the rod-plate double layer coupling.
- Published
- 2010
- Full Text
- View/download PDF
4. A Thermodynamic Method to Study the Interaction Between NaOH and Highly Carboxylated Polymeric Particles in Solution
- Author
-
del Río, J. M., Santillan, R., Vallejo, I., Grolier, J.-P. E., Jiménez-Ángeles, F., and Corea, M.
- Published
- 2015
- Full Text
- View/download PDF
5. Impact of pathogen exposure and dietary stress at weaning: application to a mucin associated in vitro model of the piglet colon (MPigut-IVM) coupled to porcine intestinal cells
- Author
-
GRESSE, Raphaële, Chaucheyras Durand, Frédérique, Garrido, Juan Jose, Denis, Sylvain, Jiménez-Ángeles, F., Beaumont, Martin, Van De Wiele, Tom, Forano, Evelyne, BLANQUET-DIOT, Stéphanie, Microbiologie Environnement Digestif Santé (MEDIS), Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Clermont Auvergne (UCA), Lallemand SAS, Universidad de Córdoba = University of Córdoba [Córdoba], Génétique Physiologie et Systèmes d'Elevage (GenPhySE ), Ecole Nationale Vétérinaire de Toulouse (ENVT), Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Université de Toulouse (UT)-École nationale supérieure agronomique de Toulouse (ENSAT), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Center for Microbial Ecology and Technology (CMET), Universiteit Gent = Ghent University (UGENT), INRAE, Rowett Institute UK, Universidad de Córdoba [Cordoba], Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-École nationale supérieure agronomique de Toulouse [ENSAT]-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), and Universiteit Gent = Ghent University [Belgium] (UGENT)
- Subjects
[SDV.MP]Life Sciences [q-bio]/Microbiology and Parasitology - Abstract
Session 2: Cross-talk between gut microbiota and the host ; Communication PO74; International audience; Enterotoxigenic Escherichia coli (ETEC) is the principal pathogen responsible for post-weaning diarrhea in newly weaned piglets. Expansion of ETEC at weaning is thought to be the consequence of various stress factors such as transient anorexia, dietary change or increase in intestinal inflammation and permeability, but the exact mechanisms remain to be elucidated. As the use of animal experiments raise more and more ethical concerns, we used a recently developed in vitro model of piglet colonic microbiome and mucobiome, the MPigut-IVM, to evaluate the effects of a simulated weaning transition and pathogen challenge at weaning. Our data suggested that the tested factors impacted the composition and functionality of the MPigut-IVM microbiota. The simulation of weaning transition led to an increase in relative abundance of the Prevotellaceae family, which was further promoted by the presence of the ETEC strain. In contrast, several beneficial families such as Bacteroidiaceae or Ruminococcaceae and gut health related short chain fatty acids like butyrate or acetate were reduced upon simulated weaning. Moreover, the incubation of MPigut-IVM filtrated effluents with porcine intestinal cell cultures showed that ETEC challenge in the in vitro model led to an increased expression of pro-inflammatory genes by the porcine cells. This study provides insights about the etiology of a dysbiotic microbiota in post-weaning piglets and showed that in vitro MPigut-IVM can be efficiently coupled to porcine epithelial cells to study host-microbiota crosstalk.P075 Periparturient Holstein cows of varying subacute ruminal acidosis phenotype differ in rumen bacterial community and
- Published
- 2021
6. Entropy driven key-lock assembly.
- Author
-
Odriozola, G., Jiménez-Ángeles, F., and Lozada-Cassou, M.
- Subjects
- *
ENTROPY , *MONTE Carlo method , *NUCLEAR reactions , *ESTIMATION theory , *SURFACE chemistry , *POTENTIAL barrier - Abstract
The effective interaction between a sphere with an open cavity (lock) and a spherical macroparticle (key), both immersed in a hard sphere fluid, is studied by means of Monte Carlo simulations. As a result, a two-dimensional map of the key-lock effective interaction potential is constructed, which leads to the proposal of a self-assembling mechanism: There exists trajectories through which the key-lock pair could assemble avoiding trespassing potential barriers. Hence, solely the entropic contribution can induce their self-assembling even in the absence of attractive forces. This study points out the solvent contribution within the underlying mechanisms of substrate-protein assembly/disassembly processes, which are important steps of the enzyme catalysis and protein mediated transport. [ABSTRACT FROM AUTHOR]
- Published
- 2008
- Full Text
- View/download PDF
7. A Thermodynamic Method to Study the Interaction Between NaOH and Highly Carboxylated Polymeric Particles in Solution
- Author
-
del Río, J. M., primary, Santillan, R., additional, Vallejo, I., additional, Grolier, J.-P. E., additional, Jiménez-Ángeles, F., additional, and Corea, M., additional
- Published
- 2014
- Full Text
- View/download PDF
8. A Thermodynamic Method to Study the Interaction Between NaOH and Highly Carboxylated Polymeric Particles in Solution.
- Author
-
Río, J., Santillan, R., Vallejo, I., Grolier, J.-P., Jiménez-Ángeles, F., and Corea, M.
- Subjects
POLYMER research ,CARBOXYLATION ,SODIUM hydroxide ,ISOTHERMAL titration calorimetry ,HYDRODYNAMICS ,THERMODYNAMICS ,SOLUTION (Chemistry) - Abstract
One of the most important challenges facing nanotechnology is to identify methods that relate the synthesis of nanomaterials with their final applications. This work proposes a thermodynamic method to understand the stimuli-response of functionalized polymeric particles with NaOH using the partial volumes of interaction, partial compressibilities of interaction, partial enthalpies of interaction and the average hydrodynamic diameter. These properties have been calculated from experimental measurements made by mechanical oscillation densimetry, the sound speed technique, isothermal titration calorimetry, dynamic light scattering and zeta potential. The thermodynamic method allows determination of how and where the interactions take place on the polymeric particles. From the methodological point of view, the thermodynamic fundamentals of the method were tested by simulating the partial properties calculated from volumetric data of a ternary liquid mixture taken from the literature. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
9. Two rods confined by positive plates: effective forces and charge distribution profiles
- Author
-
Odriozola, G, primary, Jiménez-Ángeles, F, additional, and Lozada-Cassou, M, additional
- Published
- 2006
- Full Text
- View/download PDF
10. Effect of Confinement on the Interaction between Two Like-Charged Rods
- Author
-
Odriozola, G., primary, Jiménez-Ángeles, F., additional, and Lozada-Cassou, M., additional
- Published
- 2006
- Full Text
- View/download PDF
11. Interfacial rheology of lanthanide binding peptide surfactants at the air-water interface.
- Author
-
Crane SA, Jiménez-Ángeles F, Wang Y, Ortuno Macias LE, Marmorstein JG, Deng J, Molaei M, Petersson EJ, Radhakrishnan R, de la Fuente-Nunez C, Olvera de la Cruz M, Tu RS, Maldarelli C, Dmochowski IJ, and Stebe KJ
- Abstract
Peptide surfactants (PEPS) are studied to capture and retain rare earth elements (REEs) at air-water interfaces to enable REE separations. Peptide sequences, designed to selectively bind REEs, depend crucially on the position of ligands within their binding loop domain. These ligands form a coordination sphere that wraps and retains the cation. We study variants of lanthanide binding tags (LBTs) designed to complex strongly with Tb
3+ . The peptide LBT5- (with net charge -5) is known to bind Tb3+ and adsorb with more REE cations than peptide molecules, suggesting that undesired non-specific coulombic interactions occur. Rheological characterization of interfaces of LBT5- and Tb3+ solutions reveal the formation of an interfacial gel. To probe whether this gelation reflects chelation among intact adsorbed LBT5- :Tb3+ complexes or destruction of the binding loop, we study a variant, LBT3- , designed to form net neutral LBT3- :Tb3+ complexes. Solutions of LBT3- and Tb3+ form purely viscous layers in the presence of excess Tb3+ , indicating that each peptide binds a single REE in an intact coordination sphere. We introduce the variant RR-LBT3- with net charge -3 and anionic ligands outside of the coordination sphere. We find that such exposed ligands promote interfacial gelation. Thus, a nuanced requirement for interfacial selectivity of PEPS is proposed: that anionic ligands outside of the coordination sphere must be avoided to prevent the non-selective recruitment of REE cations. This view is supported by simulation, including interfacial molecular dynamics simulations, and interfacial metadynamics simulations of the free energy landscape of the binding loop conformational space.- Published
- 2024
- Full Text
- View/download PDF
12. Transformations in crystals of DNA-functionalized nanoparticles by electrolytes.
- Author
-
John-Erik Reinertsen R, Jiménez-Ángeles F, Kewalramani S, Bedzyk M, and Olvera de la Cruz M
- Subjects
- Colloids chemistry, DNA chemistry, Electrolytes chemistry, Gold chemistry, Calcium chemistry, Metal Nanoparticles, Nanoparticles chemistry
- Abstract
Colloidal crystals have applications in water treatments, including water purification and desalination technologies. It is, therefore, important to understand the interactions between colloids as a function of electrolyte concentration. We study the assembly of DNA-grafted gold nanoparticles immersed in concentrated electrolyte solutions. Increasing the concentration of divalent Ca
2+ ions leads to the condensation of nanoparticles into face-centered-cubic (FCC) crystals at low electrolyte concentrations. As the electrolyte concentration increases, the system undergoes a phase change to body-centered-cubic (BCC) crystals. This phase change occurs as the interparticle distance decreases. Molecular dynamics analysis suggests that the interparticle interactions change from strongly repulsive to short-range attractive as the divalent-electrolyte concentration increases. A thermodynamic analysis suggests that increasing the salt concentration leads to significant dehydration of the nanoparticle environment. We conjecture that the intercolloid attractive interactions and dehydrated states favour the BCC structure. Our results gain insight into salting out of colloids such as proteins as the concentration of salt increases in the solution.- Published
- 2024
- Full Text
- View/download PDF
13. Reexpansion of charged nanoparticle assemblies in concentrated electrolytes.
- Author
-
Reinertsen RJE, Kewalramani S, Jiménez-Ángeles F, Weigand SJ, Bedzyk MJ, and Olvera de la Cruz M
- Abstract
Electrostatic forces in solutions are highly relevant to a variety of fields, ranging from electrochemical energy storage to biology. However, their manifestation in concentrated electrolytes is not fully understood, as exemplified by counterintuitive observations of colloidal stability and long-ranged repulsions in molten salts. Highly charged biomolecules, such as DNA, respond sensitively to ions in dilute solutions. Here, we use non-base-pairing DNA-coated nanoparticles (DNA-NP) to analyze electrostatic interactions in concentrated salt solutions. Despite their negative charge, these conjugates form colloidal crystals in solutions of sufficient divalent cation concentration. We utilize small-angle X-ray scattering (SAXS) to study such DNA-NP assemblies across the full accessible concentration ranges of aqueous CaCl
2 , MgCl2 , and SrCl2 solutions. SAXS shows that the crystallinity and phases of the assembled structures vary with cation type. For all tested salts, the aggregates contract with added ions at low salinities and then begin expanding above a cation-dependent threshold salt concentration. Wide-angle X-ray scattering (WAXS) reveals enhanced positional correlations between ions in the solution at high salt concentrations. Complementary molecular dynamics simulations show that these ion-ion interactions reduce the favorability of dense ion configurations within the DNA brushes below that of the bulk solution. Measurements in solutions with lowered permittivity demonstrate a simultaneous increase in ion coupling and decrease in the concentration at which aggregate expansion begins, thus confirming the connection between these phenomena. Our work demonstrates that interactions between charged objects continue to evolve considerably into the high-concentration regime, where classical theories project electrostatics to be of negligible consequence., Competing Interests: Competing interests statement:The authors F.J.-Á. and M.O.d.l.C. participated in a Faraday Discussion meeting on iontronics in June 2023, at Edinburgh, UK, which the reviewer S.P. and her group also attended. F.J.-Á. presented an article [Felipe Jiménez-Ángeles, Ali Ehlen, and Monica Olvera de la Cruz, Faraday Discuss. 246, 576–591 (2023)], and a member of the group of S.P. also presented an article in this meeting [Y. K. Catherine Fung and Susan Perkin, Faraday Discuss. 246, 370–386 (2023)]. The questions and answers on the presentations during all the different session in the meting are also published in Faraday Discuss. 2023, Vol. 246, under manuscripts with titles such as “Ionotronic coupling: general discussion” and “Iontronics under confinement: general discussion”, where F.J.-Á. participated on pages 592–617 and 157–178 and M.O.d.l.C. on pages 592–617, 466–486, and 322–355. These manuscripts are only reports on the discussions among the participants concerning articles presented during the meeting; For example, F.J.-Á. answered a short question by S.P. (in addition to 5 more questions by others) published on Vol. 246, pages 592–617, and M.O.d.l.C. asked a question to Christian Holm in the same session. Both F.J.-Á. and M.O.d.l.C. declare no conflict of interest with S.P.- Published
- 2024
- Full Text
- View/download PDF
14. Iontronic coupling: general discussion.
- Author
-
Abayzeed S, Anwar T, Barnaveli A, Bazant MZ, Bocquet L, Donev A, Dryfe RAW, Faez S, Janardanan A, Jiménez-Ángeles F, Kamsma TM, Kanoufi F, Kornyshev AA, Lemay SG, Levin Y, Marbach S, Montes de Oca J, Robin P, Siwy ZS, Stein D, van Roij R, Vidaković-Koch T, Yossifon G, and Zhang Y
- Published
- 2023
- Full Text
- View/download PDF
15. Iontronic microscopy: general discussion.
- Author
-
Aarts M, Abayzeed S, Barnaveli A, Bocquet L, Dryfe RAW, Duleba D, Faez S, Fung YKC, Holm C, Janardanan A, Jiménez-Ángeles F, Johnson R, Kanoufi F, Levin Y, Marbach S, Marchioro A, Mugele F, Olvera de la Cruz M, Pennathur S, Perkin S, Pireddu G, Robin P, Rotenberg B, Siretanu I, Siwy ZS, Stein D, Ton J, Valtiner M, van Roij R, Voïtchovsky K, Yossifon G, and Zhang Z
- Published
- 2023
- Full Text
- View/download PDF
16. Surface polarization enhances ionic transport and correlations in electrolyte solutions nanoconfined by conductors.
- Author
-
Jiménez-Ángeles F, Ehlen A, and Olvera de la Cruz M
- Abstract
Layered materials that perform mixed electron and ion transport are promising for energy harvesting, water desalination, and bioinspired functionalities. These functionalities depend on the interaction between ionic and electronic charges on the surface of materials. Here we investigate ion transport by an external electric field in an electrolyte solution confined in slit-like channels formed by two surfaces separated by distances that fit only a few water layers. We study different electrolyte solutions containing monovalent, divalent, and trivalent cations, and we consider walls made of non-polarizable surfaces and conductors. We show that considering the surface polarization of the confining surfaces can result in a significant increase in ionic conduction. The ionic conductivity is increased because the conductors' screening of electrostatic interactions enhances ionic correlations, leading to faster collective transport within the slit. While important, the change in water's dielectric constant in confinement is not enough to explain the enhancement of ion transport in polarizable slit-like channels.
- Published
- 2023
- Full Text
- View/download PDF
17. Iontronics under confinement: general discussion.
- Author
-
Bazant MZ, Bocquet L, Cicoira F, Duarte Sánchez DF, Farrell E, Holm C, Igor S, Janardanan A, Jiménez-Ángeles F, Johnson R, Kamsma TM, Kanoufi F, Kornyshev AA, Lemay SG, Levin Y, Marbach S, Olvera de la Cruz M, Perkin S, Pireddu G, Robin P, Rotenberg B, Schlaich A, Siwy ZS, Stein D, Thorneywork A, Valtiner M, van Roij R, Yossifon G, and Zhang Y
- Published
- 2023
- Full Text
- View/download PDF
18. Microporous water with high gas solubilities.
- Author
-
Erdosy DP, Wenny MB, Cho J, DelRe C, Walter MV, Jiménez-Ángeles F, Qiao B, Sanchez R, Peng Y, Polizzotti BD, de la Cruz MO, and Mason JA
- Abstract
Liquids with permanent microporosity can absorb larger quantities of gas molecules than conventional solvents
1 , providing new opportunities for liquid-phase gas storage, transport and reactivity. Current approaches to designing porous liquids rely on sterically bulky solvent molecules or surface ligands and, thus, are not amenable to many important solvents, including water2-4 . Here we report a generalizable thermodynamic strategy to preserve permanent microporosity and impart high gas solubilities to liquid water. Specifically, we show how the external and internal surface chemistry of microporous zeolite and metal-organic framework (MOF) nanocrystals can be tailored to promote the formation of stable dispersions in water while maintaining dry networks of micropores that are accessible to gas molecules. As a result of their permanent microporosity, these aqueous fluids can concentrate gases, including oxygen (O2 ) and carbon dioxide (CO2 ), to much higher densities than are found in typical aqueous environments. When these fluids are oxygenated, record-high capacities of O2 can be delivered to hypoxic red blood cells, highlighting one potential application of this new class of microporous liquids for physiological gas transport., (© 2022. The Author(s), under exclusive licence to Springer Nature Limited.)- Published
- 2022
- Full Text
- View/download PDF
19. Probing the size-dependent polarizability of mesoscopic ionic clusters and their induced-dipole interactions.
- Author
-
Nguyen TD, Jiménez-Ángeles F, and Olvera de la Cruz M
- Abstract
Mesoscopic clusters composed of oppositely charged particles are ubiquitous in synthetic and biological soft materials. The effective interaction between these clusters is influenced by their polarizability, that is, the ability of their constituent charges to re-arrange in response to an external electrical field. Here, using coarse-grained simulations, we show that the polarizability of electrically neutral ionic clusters decreases as the number of constituent charges increases and/or their Coulombic interaction strength increases for various ion valencies, ion densities, and degrees of cluster boundary hardness. For clusters of random ionomers and their counterions, their polarizability is shown to depend on the number of polymer chains. The variation of the cluster polarizability with the cluster size indicates that throughout the assembly, the induced-dipole interactions between the clusters may be reduced substantially as they acquire more charges while maintaining zero net charge. Under certain conditions, the induced-dipole interactions may become repulsive, as inferred from our simulations with a polarizable solvent. As a result, the dipole-induced related interactions can serve as a counterbalancing force that contributes to the self-limiting aggregation of charge-containing assemblies.
- Published
- 2021
- Full Text
- View/download PDF
20. A Modeling-Based Design to Engineering Protein Hydrogels with Random Copolymers.
- Author
-
Cardellini A, Jiménez-Ángeles F, Asinari P, and Olvera de la Cruz M
- Subjects
- Hydrophobic and Hydrophilic Interactions, Proteins, Hydrogels, Polymers
- Abstract
Protein enzymes have shown great potential in numerous technological applications. However, the design of supporting materials is needed to preserve protein functionality outside their native environment. Direct enzyme-polymer self-assembly offers a promising alternative to immobilize proteins in an aqueous solution, achieving higher control of their stability and enzymatic activity in industrial applications. Herein, we propose a modeling-based design to engineering hydrogels of cytochrome P450 and of PETase with styrene/2-vinylpyridine (2VP) random copolymers. By tuning the copolymer fraction of polar groups and of charged groups via quaternization of 2VP for coassembly with cytochrome P450 and via sulfonation of styrene for coassembly with PETase, we provide quantitative guidelines to select either a protein-polymer hydrogel structure or a single-protein encapsulation. The results highlight that, regardless of the protein surface domains, the presence of polar interactions and hydration effects promote the formation of a more elongated enzyme-polymer complex, suggesting a membrane-like coassembly. On the other hand, the effectiveness of a single-protein encapsulation is reached by decreasing the fraction of polar groups and by increasing the charge fraction up to 15%. Our computational analysis demonstrates that the enzyme-polymer assemblies are first promoted by the hydrophobic interactions which lead the protein nonpolar residues to achieve the maximum coverage and to play the role of the most robust contact points. The mechanisms of coassembly are unveiled in the light of both protein and polymer physical-chemistry, providing bioconjugate phase diagrams for the optimal material design.
- Published
- 2021
- Full Text
- View/download PDF
21. Insights into the Enhanced Catalytic Activity of Cytochrome c When Encapsulated in a Metal-Organic Framework.
- Author
-
Chen Y, Jiménez-Ángeles F, Qiao B, Krzyaniak MD, Sha F, Kato S, Gong X, Buru CT, Chen Z, Zhang X, Gianneschi NC, Wasielewski MR, Olvera de la Cruz M, and Farha OK
- Subjects
- Benzothiazoles chemistry, Biocatalysis, Catalytic Domain, Cytochromes c chemistry, Density Functional Theory, Heme chemistry, Molecular Dynamics Simulation, Oxidation-Reduction, Spectrophotometry, Sulfonic Acids chemistry, Cytochromes c metabolism, Metal-Organic Frameworks chemistry
- Abstract
The encapsulation of enzymes within porous materials has shown great promise, not only in protecting the enzymes from denaturation under nonbiological environments, but also, in some cases, in facilitating their enzymatic reaction rates at favorable reaction conditions. While a number of hypotheses have been developed to explain this phenomenon, the detailed structural changes of the enzymes upon encapsulation within the porous material, which are closely related to their activity, remain largely elusive. Herein, the structural change of cytochrome c (Cyt c) upon encapsulation within a hierarchical metal-organic framework, NU-1000, is investigated through a combination of experimental and computational methods, such as electron paramagnetic resonance, solid-state ultraviolet-visible spectroscopy, and all-atom explicit solvent molecular dynamics simulations. The enhanced catalytic performance of Cyt c after being encapsulated within NU-1000 is supported by the physical and in silico observations of a change around the heme ferric active center.
- Published
- 2020
- Full Text
- View/download PDF
22. Water follows polar and nonpolar protein surface domains.
- Author
-
Qiao B, Jiménez-Ángeles F, Nguyen TD, and Olvera de la Cruz M
- Subjects
- Amino Acids chemistry, Hydrophobic and Hydrophilic Interactions, Models, Chemical, Models, Molecular, Molecular Dynamics Simulation, Solubility, Surface Properties, Protein Domains, Proteins chemistry, Water chemistry
- Abstract
The conformation of water around proteins is of paramount importance, as it determines protein interactions. Although the average water properties around the surface of proteins have been provided experimentally and computationally, protein surfaces are highly heterogeneous. Therefore, it is crucial to determine the correlations of water to the local distributions of polar and nonpolar protein surface domains to understand functions such as aggregation, mutations, and delivery. By using atomistic simulations, we investigate the orientation and dynamics of water molecules next to 4 types of protein surface domains: negatively charged, positively charged, and charge-neutral polar and nonpolar amino acids. The negatively charged amino acids orient around 98% of the neighboring water dipoles toward the protein surface, and such correlation persists up to around 16 Å from the protein surface. The positively charged amino acids orient around 94% of the nearest water dipoles against the protein surface, and the correlation persists up to around 12 Å. The charge-neutral polar and nonpolar amino acids are also orienting the water neighbors in a quantitatively weaker manner. A similar trend was observed in the residence time of the nearest water neighbors. These findings hold true for 3 technically important enzymes (PETase, cytochrome P450, and organophosphorus hydrolase). Our results demonstrate that the water-amino acid degree of correlation follows the same trend as the amino acid contribution in proteins solubility, namely, the negatively charged amino acids are the most beneficial for protein solubility, then the positively charged amino acids, and finally the charge-neutral amino acids., Competing Interests: The authors declare no conflict of interest.
- Published
- 2019
- Full Text
- View/download PDF
23. Self-Assembly of Charge-Containing Copolymers at the Liquid-Liquid Interface.
- Author
-
Jiménez-Ángeles F, Kwon HK, Sadman K, Wu T, Shull KR, and Olvera de la Cruz M
- Abstract
Quantitatively understanding the self-assembly of amphiphilic macromolecules at liquid-liquid interfaces is a fundamental scientific concern due to its relevance to a broad range of applications including bottom-up nanopatterning, protein encapsulation, oil recovery, drug delivery, and other technologies. Elucidating the mechanisms that drive assembly of amphiphilic macromolecules at liquid-liquid interfaces is challenging due to the combination of hydrophobic, hydrophilic, and Coulomb interactions, which require consideration of the dielectric mismatch, solvation effects, ionic correlations, and entropic factors. Here we investigate the self-assembly of a model block copolymer with various charge fractions at the chloroform-water interface. We analyze the adsorption and conformation of poly(styrene)- block -poly(2-vinylpyridine) (PS- b -P2VP) and of the homopolymer poly(2-vinylpyridine) (P2VP) with varying charge fraction, which is controlled via a quaternization reaction and distributed randomly along the backbone. Interfacial tension measurements show that the polymer adsorption increases only marginally at low charge fractions (<5%) but increases more significantly at higher charge fractions for the copolymer, while the corresponding randomly charged P2VP homopolymer analogues display much more sensitivity to the presence of charged groups. Molecular dynamics (MD) simulations of the experimental systems reveal that the diblock copolymer (PS- b -P2VP) interfacial activity could be mediated by the formation of a rich set of complex interfacial copolymer aggregates. Circular domains to elongated stripes are observed in the simulations at the water-chloroform interface as the charge fraction increases. These structures are shown to resemble the spherical and cylindrical helicoid structures observed in bulk chloroform as the charge fraction increases. The self-assembly of charge-containing copolymers is found to be driven by the association of the charged component in the hydrophilic block, with the hydrophobic segments extending away from the hydrophilic cores into the chloroform phase., Competing Interests: The authors declare no competing financial interest.
- Published
- 2019
- Full Text
- View/download PDF
24. Hydrophobic Hydration and the Effect of NaCl Salt in the Adsorption of Hydrocarbons and Surfactants on Clathrate Hydrates.
- Author
-
Jiménez-Ángeles F and Firoozabadi A
- Abstract
Adsorption of functional molecules on the surface of hydrates is key in the understanding of hydrate inhibitors. We investigate the adsorption of a hydrocarbon chain, nonionic and ionic surfactants, and ions at the hydrate-aqueous interface. Our results suggest a strong connection between the water ordering around solutes in bulk and the affinity for the hydrates surface. We distinguish two types of water ordering around solutes: (i) hydrophobic hydration where water molecules form a hydrogen bond network similar to clathrate hydrates, and (ii) ionic hydration where water molecules align according to the polarity of an ionic group. The nonionic surfactant and the hydrocarbon chain induce hydrophobic hydration and are favorably adsorbed on the hydrate surface. Adsorption of ions and the ionic headgroups on the hydrate surface is not favorable because ionic hydration and the hydrogen bond structure of hydrates are incompatible. The nonionic surfactant is adsorbed by the headgroup and tail while adsorption of the ionic surfactants is not favorable through the head. Water ordering is analyzed using the hydrogen bond and tetrahedral density profiles as a function of the distance to the chemical groups. The adsorption of solutes is studied through the free energy profiles as a function of the distance to the hydrate surface. Salt lowers the melting temperature of hydrates, disrupts hydrophobic hydration, reduces the solubility of solutes in the aqueous solution, and increases the propensity of solutes to be adsorbed on hydrate surfaces. Our studies are performed by the unbiased and steered molecular dynamics simulations. The results are in line with experiments on the effect of salt and alkanes in hydrate antiagglomeration., Competing Interests: The authors declare no competing financial interest.
- Published
- 2018
- Full Text
- View/download PDF
25. Effects of mixed discrete surface charges on the electrical double layer.
- Author
-
Jiménez-Ángeles F
- Abstract
Adsorption of surface coions and charge reversal are induced at the electrical double layer of a wall charged with positive and negative surface sites next to an electrolyte solution. While for the considered surface charge density these effects are found over a wide range of conditions, they are not observed for the typically employed surface models in equivalent conditions. Important consequences in electrophoresis experiments for different colloids with equal effective surface charge density are foreseen. This study is carried out by means of molecular dynamics simulations.
- Published
- 2012
- Full Text
- View/download PDF
26. Polarity inversion of ζ-potential in concentrated colloidal dispersions.
- Author
-
Manzanilla-Granados HM, Jiménez-Ángeles F, and Lozada-Cassou M
- Abstract
A concentrated colloidal dispersion is studied by applying an integral equations theory to the colloidal primitive model fluid. Important effects, attributed to large size and charge and to the finite concentration of colloidal particles, are found. We observe a polarity inversion of ζ-potential for concentrated colloidal dispersions, while it is not present for a single colloidal particle at infinite dilution. An excellent qualitative agreement between our theoretical predictions and our computer simulations is observed.
- Published
- 2011
- Full Text
- View/download PDF
27. Stability mechanisms for plate-like nanoparticles immersed in a macroion dispersion.
- Author
-
Jiménez-Ángeles F, Odriozola G, and Lozada-Cassou M
- Abstract
An integral equation theory and Monte Carlo simulations are applied to study a model macroion solution confined between two parallel plates immersed in a 1:1 electrolyte and the macroions' counterions. We analyze the cases in which plates are: (a) uncharged; (b) when they are like-charged to the macroions; (c) when they are oppositely charged to the macroions. For all cases a long range oscillatory behavior of the induced charge density between the plates is found (implying an overcompensation/undercompensation of the plates' charge density) and a correlation between the confined and outside fluids. The behavior of the force is discussed in terms of the macroion and ion structure inside and outside the plates. A good agreement is found between theoretical and simulation results.
- Published
- 2009
- Full Text
- View/download PDF
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.