Effect of an ionic environment on membrane fouling: a molecular dynamics study

2021 ◽  
Author(s):  
Shivam Tiwari ◽  
Abhijit Gogoi ◽  
K. Anki Reddy
Keyword(s):  
Molecular Dynamics ◽  
Graphene Oxide ◽  
Membrane Fouling ◽  
Md Simulations ◽  
Ionic Environment

The effect of the ionic environment on membrane fouling was investigated for polyamide (PA) and graphene oxide (GO) membranes using equilibrium molecular dynamics (MD) simulations.

scholarly journals A Possible Mechanism of Graphene Oxide to Enhance Thermostability of D-Psicose 3-Epimerase Revealed by Molecular Dynamics Simulations

2021 ◽  
Vol 22 (19) ◽  
pp. 10813
Author(s):  
Congcong Li ◽  
Zhongkui Lu ◽  
Min Wang ◽  
Siao Chen ◽  
Lu Han ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Thermal Stability ◽  
Graphene Oxide ◽  
Md Simulations ◽  
Strong Interactions ◽  
Limiting Factor ◽  
Active Site Residues ◽  
Detailed Mechanism ◽  
Dynamics Simulations ◽  
Thermal Stability Of

Thermal stability is a limiting factor for effective application of D-psicose 3-epimerase (DPEase) enzyme. Recently, it was reported that the thermal stability of DPEase was improved by immobilizing enzymes on graphene oxide (GO) nanoparticles. However, the detailed mechanism is not known. In this study, we investigated interaction details between GO and DPEase by performing molecular dynamics (MD) simulations. The results indicated that the domain (K248 to D268) of DPEase was an important anchor for immobilizing DPEase on GO surface. Moreover, the strong interactions between DPEase and GO can prevent loop α1′-α1 and β4-α4 of DPEase from the drastic fluctuation. Since these two loops contained active site residues, the geometry of the active pocket of the enzyme remained stable at high temperature after the DPEase was immobilized by GO, which facilitated efficient catalytic activity of the enzyme. Our research provided a detailed mechanism for the interaction between GO and DPEase at the nano–biology interface.

Molecular dynamics simulations reveal how graphene oxide stabilizes and activates lipase in an anhydrous gas

2019 ◽  
Vol 21 (45) ◽  
pp. 25425-25430 ◽  
Author(s):  
Zhongwang Fu ◽  
Weina Xu ◽  
Gong Chen ◽  
Zheyu Wang ◽  
Diannan Lu ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Graphene Oxide ◽  
Simulated Annealing ◽  
Molecular Dynamics Simulations ◽  
Md Simulations ◽  
Candida Antarctica ◽  
Lipase B ◽  
Annealing Procedure ◽  
Dynamics Simulations ◽  
Simulated Annealing Procedure

The interaction between Candida antarctica lipase B (CALB) and graphene oxide (GO) in an anhydrous gas was studied using molecular dynamics (MD) simulations augmented with a simulated annealing procedure to accelerate relaxation towards equilibrium.

scholarly journals Interaction between Graphene-Based Materials and Small Ag, Cu, and CuO Clusters: A Molecular Dynamics Study

Nanomaterials ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1378
Author(s):  
Isabel Lado-Touriño ◽  
Alicia Páez-Pavón
Keyword(s):  
Molecular Dynamics ◽  
Graphene Oxide ◽  
Mean Square Displacement ◽  
Md Simulations ◽  
Great Promise ◽  
Resistant Bacteria ◽  
Pristine Graphene ◽  
Metallic Oxide ◽  
Antibacterial Compounds ◽  
Adsorption Energies

The excessive use of antibiotics has contributed to the rise in antibiotic-resistant bacteria, and thus, new antibacterial compounds must be developed. Composite materials based on graphene and its derivatives doped with metallic and metallic oxide nanoparticles, particularly Ag, Cu, and Cu oxides, hold great promise. These materials are often modified with polyethylene glycol (PEG) to improve their pharmacokinetic behavior and their solubility in biological media. In this work, we performed molecular dynamics (MD) simulations to study the interaction between small Ag, Cu, and CuO clusters and several graphene-based materials. These materials include pristine graphene (PG) and pristine graphene nanoplatelets (PGN) as well as PEGylated graphene oxide (GO_PEG) and PEGylated graphene oxide nanoplatelets (GO-PEG_N). We calculated the adsorption energies, mean equilibrium distances between the nanoparticles and graphene surfaces, and mean square displacement (MSD) of the nanoclusters. The results show that PEGylation favors the adsorption of the clusters on the graphene surfaces, causing an increase in adsorption energies and a decrease in both distances and MSD values. The strengthening of the interaction could be crucial to obtain effective antibacterial compounds.

scholarly journals Molecular Mechanisms on the Selectivity Enhancement of Ascorbic Acid, Dopamine, and Uric Acid by Serine Oligomers Decoration on Graphene Oxide: A Molecular Dynamics Study

2021 ◽  
Author(s):  
Threravee Sanglao ◽  
Pattanan Oungkanitanon ◽  
Piyapong Asanithi ◽  
Thana Sutthibutpong
Keyword(s):  
Molecular Dynamics ◽  
Ascorbic Acid ◽  
Uric Acid ◽  
Graphene Oxide ◽  
Molecular Mechanisms ◽  
Simultaneous Detection ◽  
Md Simulations ◽  
Bond Forming ◽  
Solvent Environment

The selectivity in the simultaneous detection of ascorbic acid (AA), dopamine (DA), and uric acid (UA) has been an open problem in the biosensing field. Many surface modification methods were carried out for glassy carbon electrodes (GCE), including the use of graphene oxide and amino acids as a selective layer. In this work, molecular dynamics (MD) simulations were performed to investigate the role of serine oligomers on the selectivity of the AA, DA, UA analytes. Our models consisted of a graphene oxide (GO) sheet under a solvent environment. Serine tetramers were added into the simulation box and were adsorbed on the GO surface. Then, the adsorption of each analyte on the mixed surface was monitored from MD trajectories. It was found that the adsorption of AA was preferred by serine oligomers due to the largest number of hydrogen-bond forming functional groups of AA, while UA was the least preferred due to its highest aromaticity. Finally, the role of hydrogen bonds on the electron transfer selectivity of biosensors was discussed with some previous studies.

Efficient Treatment of Fixed and Induced Dipolar Interactions

2000 ◽  
Vol 653 ◽  
Author(s):  
Celeste Sagui ◽  
Thoma Darden
Keyword(s):  
Molecular Dynamics ◽  
Md Simulations ◽  
Lagrangian Formalism ◽  
Dipolar Interactions ◽  
Time Step ◽  
Efficient Treatment ◽  
Particle Mesh Ewald ◽  
Fixed Charges ◽  
Self Consistency ◽  
Induced Dipoles

AbstractFixed and induced point dipoles have been implemented in the Ewald and Particle-Mesh Ewald (PME) formalisms. During molecular dynamics (MD) the induced dipoles can be propagated along with the atomic positions either by interation to self-consistency at each time step, or by a Car-Parrinello (CP) technique using an extended Lagrangian formalism. The use of PME for electrostatics of fixed charges and induced dipoles together with a CP treatment of dipole propagation in MD simulations leads to a cost overhead of only 33% above that of MD simulations using standard PME with fixed charges, allowing the study of polarizability in largemacromolecular systems.

Split the Charge Difference in Two! a Rule of Thumb for Adding Proper Amounts of Ions in MD Simulations

2020 ◽  
Author(s):  
Matías R. Machado ◽  
Sergio Pantano
Keyword(s):  
Molecular Dynamics ◽  
Ionic Strength ◽  
Molecular Simulations ◽  
Md Simulations ◽  
Good Practices ◽  
Rule Of Thumb ◽  
Ionic Concentrations

<p> Despite the relevance of properly setting ionic concentrations in Molecular Dynamics (MD) simulations, methods or practical rules to set ionic strength are scarce and rarely documented. Based on a recently proposed thermodynamics method we provide an accurate rule of thumb to define the electrolytic content in simulation boxes. Extending the use of good practices in setting up MD systems is promptly needed to ensure reproducibility and consistency in molecular simulations.</p>

Assessing the Antimalarial Potentials of Phytochemicals: Virtual Screening, Molecular Dynamics and In-Vitro Investigations

2019 ◽  
Vol 16 (3) ◽  
pp. 291-300
Author(s):  
Saumya K. Patel ◽  
Mohd Athar ◽  
Prakash C. Jha ◽  
Vijay M. Khedkar ◽  
Yogesh Jasrai ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Structural Integrity ◽  
Md Simulations ◽  
Tylophora Indica ◽  
Multidrug Resistance Protein 1 ◽  
Receptor Complexes ◽  
Resistance Protein ◽  
Dynamics Simulations ◽  
Stable Trajectory

Background: Combined in-silico and in-vitro approaches were adopted to investigate the antiplasmodial activity of Catharanthus roseus and Tylophora indica plant extracts as well as their isolated components (vinblastine, vincristine and tylophorine). </P><P> Methods: We employed molecular docking to prioritize phytochemicals from a library of 26 compounds against Plasmodium falciparum multidrug-resistance protein 1 (PfMDR1). Furthermore, Molecular Dynamics (MD) simulations were performed for a duration of 10 ns to estimate the dynamical structural integrity of ligand-receptor complexes. </P><P> Results: The retrieved bioactive compounds viz. tylophorine, vinblastin and vincristine were found to exhibit significant interacting behaviour; as validated by in-vitro studies on chloroquine sensitive (3D7) as well as chloroquine resistant (RKL9) strain. Moreover, they also displayed stable trajectory (RMSD, RMSF) and molecular properties with consistent interaction profile in molecular dynamics simulations. </P><P> Conclusion: We anticipate that the retrieved phytochemicals can serve as the potential hits and presented findings would be helpful for the designing of malarial therapeutics.

scholarly journals On the Use of the Discrete Constant pH Molecular Dynamics to Describe the Conformational Space of Peptides

Polymers ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 99
Author(s):  
Cristian Privat ◽  
Sergio Madurga ◽  
Francesc Mas ◽  
Jaime Rubio-Martínez
Keyword(s):  
Molecular Dynamics ◽  
Amino Acids ◽  
Md Simulations ◽  
Point Of View ◽  
Conformational Space ◽  
Conformational Sampling ◽  
Protonation State ◽  
Constant Ph ◽  
Biochemical Systems ◽  
Constant Ph Molecular Dynamics

Solvent pH is an important property that defines the protonation state of the amino acids and, therefore, modulates the interactions and the conformational space of the biochemical systems. Generally, this thermodynamic variable is poorly considered in Molecular Dynamics (MD) simulations. Fortunately, this lack has been overcome by means of the Constant pH Molecular Dynamics (CPHMD) methods in the recent decades. Several studies have reported promising results from these approaches that include pH in simulations but focus on the prediction of the effective pKa of the amino acids. In this work, we want to shed some light on the CPHMD method and its implementation in the AMBER suitcase from a conformational point of view. To achieve this goal, we performed CPHMD and conventional MD (CMD) simulations of six protonatable amino acids in a blocked tripeptide structure to compare the conformational sampling and energy distributions of both methods. The results reveal strengths and weaknesses of the CPHMD method in the implementation of AMBER18 version. The change of the protonation state according to the chemical environment is presumably an improvement in the accuracy of the simulations. However, the simulations of the deprotonated forms are not consistent, which is related to an inaccurate assignment of the partial charges of the backbone atoms in the CPHMD residues. Therefore, we recommend the CPHMD methods of AMBER program but pointing out the need to compare structural properties with experimental data to bring reliability to the conformational sampling of the simulations.

scholarly journals Unveiling Carbon Dioxide and Ethanol Diffusion in Carbonated Water-Ethanol Mixtures by Molecular Dynamics Simulations

Molecules ◽  
2021 ◽  
Vol 26 (6) ◽  
pp. 1711
Author(s):  
Mohamed Ahmed Khaireh ◽  
Marie Angot ◽  
Clara Cilindre ◽  
Gérard Liger-Belair ◽  
David A. Bonhommeau
Keyword(s):  
Carbon Dioxide ◽  
Molecular Dynamics ◽  
Diffusion Coefficients ◽  
Hydrodynamic Radius ◽  
Md Simulations ◽  
Molecular Models ◽  
Experimental Values ◽  
Carbon Dioxide Co2 ◽  
Dynamics Simulations ◽  
Apparent Disagreement

The diffusion of carbon dioxide (CO2) and ethanol (EtOH) is a fundamental transport process behind the formation and growth of CO2 bubbles in sparkling beverages and the release of organoleptic compounds at the liquid free surface. In the present study, CO2 and EtOH diffusion coefficients are computed from molecular dynamics (MD) simulations and compared with experimental values derived from the Stokes-Einstein (SE) relation on the basis of viscometry experiments and hydrodynamic radii deduced from former nuclear magnetic resonance (NMR) measurements. These diffusion coefficients steadily increase with temperature and decrease as the concentration of ethanol rises. The agreement between theory and experiment is suitable for CO2. Theoretical EtOH diffusion coefficients tend to overestimate slightly experimental values, although the agreement can be improved by changing the hydrodynamic radius used to evaluate experimental diffusion coefficients. This apparent disagreement should not rely on limitations of the MD simulations nor on the approximations made to evaluate theoretical diffusion coefficients. Improvement of the molecular models, as well as additional NMR measurements on sparkling beverages at several temperatures and ethanol concentrations, would help solve this issue.

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