scholarly journals Detonation initiation in solid explosive: MD simulation using AB interatomic potential

2017 ◽  
Author(s):  
Semen Murzov ◽  
Vasily Zhakhovsky
Author(s):  
Anh Tran ◽  
Yan Wang

In molecular dynamics (MD) simulation, the two main sources of uncertainty are the interatomic potential functions and thermal fluctuation. The accuracy of the interatomic potential functions plays a vital role toward the reliability of MD simulation prediction. Reliable molecular dynamics (R-MD) is an interval-based MD simulation platform, where atomistic positions and velocities are represented as Kaucher (or generalized) intervals to capture the uncertainty associated with the inter-atomic potentials. The advantage of this uncertainty quantification (UQ) approach is that the uncertainty effect can be assessed on-the-fly with only one run of simulation, and thus the computational time for UQ is significantly reduced. In this paper, an extended interval statistical ensemble is introduced to quantify the uncertainty associated with the system control variables, such as temperature and pressure at each time-step. This method allows for quantifying and propagating the uncertainty in the system as MD simulation advances. An example of interval isothermal-isobaric (NPT) ensemble is implemented to demonstrate the feasibility of applying the intrusive UQ technique toward MD simulation.


2016 ◽  
Vol 258 ◽  
pp. 69-72
Author(s):  
Ryo Kobayashi ◽  
Tomoyuki Tamura ◽  
Ichiro Takeuchi ◽  
Shuji Ogata

The validity of the molecular dynamics (MD) simulation is highly dependent on the accuracy or reproducibility of interatomic potentials used in the MD simulation. The neural-network (NN) interatomic potential is one of promising interatomic potentials based on machine-learning method. However, there are some parameters that should be determined heuristically before making the NN potential, such as the shape and number of basis functions. We have developed a new approach to select only relevant basis functions from a lot of candidates systematically and less heuristically without loosing the accuracy of the potential. The present NN potential for Si system shows very good agreements with the results obtained using ab-initio calculations.


1999 ◽  
Vol 96 (10) ◽  
pp. 1491-1507 ◽  
Author(s):  
A. J. DYSON, P. V. SMITH

2020 ◽  
Author(s):  
Sahar Qazi ◽  
Mustafa Alhaji Isa ◽  
Adam Mustapha ◽  
Khalid Raza ◽  
Ibrahim Alkali Allamin ◽  
...  

<p>The Severe Acute Respiratory Syndrome 2 (SARS-CoV-2) is an infectious virus that causes mild to severe life-threatening upper respiratory tract infection. The virus emerged in Wuhan, China in 2019, and later spread across the globe. Its genome has been completely sequenced and based on the genomic information, the virus possessed 3C-Like Main Protease (3CLpro), an essential multifunctional enzyme that plays a vital role in the replication and transcription of the virus by cleaving polyprotein at eleven various sites to produce different non-structural proteins. This makes the protein an important target for drug design and discovery. Herein, we analyzed the interaction between the 3CLpro and potential inhibitory compounds identified from the extracts of <i>Zingiber offinale</i> and <i>Anacardium occidentale</i> using in silico docking and Molecular Dynamics (MD) Simulation. The crystal structure of SARS-CoV-2 main protease in complex with 02J (5-Methylisoxazole-3-carboxylic acid) and PEJ (composite ligand) (PDB Code: 6LU7,2.16Å) retrieved from Protein Data Bank (PDB) and subject to structure optimization and energy minimization. A total of twenty-nine compounds were obtained from the extracts of <i>Zingiber offinale </i>and the leaves of <i>Anacardium occidentale. </i>These compounds were screened for physicochemical (Lipinski rule of five, Veber rule, and Egan filter), <i>Pan</i>-Assay Interference Structure (PAINS), and pharmacokinetic properties to determine the Pharmaceutical Active Ingredients (PAIs). Of the 29 compounds, only nineteen (19) possessed drug-likeness properties with efficient oral bioavailability and less toxicity. These compounds subjected to molecular docking analysis to determine their binding energies with the 3CLpro. The result of the analysis indicated that the free binding energies of the compounds ranged between ˗5.08 and -10.24kcal/mol, better than the binding energies of 02j (-4.10kcal/mol) and PJE (-5.07kcal.mol). Six compounds (CID_99615 = -10.24kcal/mol, CID_3981360 = 9.75kcal/mol, CID_9910474 = -9.14kcal/mol, CID_11697907 = -9.10kcal/mol, CID_10503282 = -9.09kcal/mol and CID_620012 = -8.53kcal/mol) with good binding energies further selected and subjected to MD Simulation to determine the stability of the protein-ligand complex. The results of the analysis indicated that all the ligands form stable complexes with the protein, although, CID_9910474 and CID_10503282 had a better stability when compared to other selected phytochemicals (CID_99615, CID_3981360, CID_620012, and CID_11697907). </p>


2020 ◽  
Author(s):  
Sahar Qazi ◽  
Mustafa Alhaji Isa ◽  
Adam Mustapha ◽  
Khalid Raza ◽  
Ibrahim Alkali Allamin ◽  
...  

<p>The Severe Acute Respiratory Syndrome 2 (SARS-CoV-2) is an infectious virus that causes mild to severe life-threatening upper respiratory tract infection. The virus emerged in Wuhan, China in 2019, and later spread across the globe. Its genome has been completely sequenced and based on the genomic information, the virus possessed 3C-Like Main Protease (3CLpro), an essential multifunctional enzyme that plays a vital role in the replication and transcription of the virus by cleaving polyprotein at eleven various sites to produce different non-structural proteins. This makes the protein an important target for drug design and discovery. Herein, we analyzed the interaction between the 3CLpro and potential inhibitory compounds identified from the extracts of <i>Zingiber offinale</i> and <i>Anacardium occidentale</i> using in silico docking and Molecular Dynamics (MD) Simulation. The crystal structure of SARS-CoV-2 main protease in complex with 02J (5-Methylisoxazole-3-carboxylic acid) and PEJ (composite ligand) (PDB Code: 6LU7,2.16Å) retrieved from Protein Data Bank (PDB) and subject to structure optimization and energy minimization. A total of twenty-nine compounds were obtained from the extracts of <i>Zingiber offinale </i>and the leaves of <i>Anacardium occidentale. </i>These compounds were screened for physicochemical (Lipinski rule of five, Veber rule, and Egan filter), <i>Pan</i>-Assay Interference Structure (PAINS), and pharmacokinetic properties to determine the Pharmaceutical Active Ingredients (PAIs). Of the 29 compounds, only nineteen (19) possessed drug-likeness properties with efficient oral bioavailability and less toxicity. These compounds subjected to molecular docking analysis to determine their binding energies with the 3CLpro. The result of the analysis indicated that the free binding energies of the compounds ranged between ˗5.08 and -10.24kcal/mol, better than the binding energies of 02j (-4.10kcal/mol) and PJE (-5.07kcal.mol). Six compounds (CID_99615 = -10.24kcal/mol, CID_3981360 = 9.75kcal/mol, CID_9910474 = -9.14kcal/mol, CID_11697907 = -9.10kcal/mol, CID_10503282 = -9.09kcal/mol and CID_620012 = -8.53kcal/mol) with good binding energies further selected and subjected to MD Simulation to determine the stability of the protein-ligand complex. The results of the analysis indicated that all the ligands form stable complexes with the protein, although, CID_9910474 and CID_10503282 had a better stability when compared to other selected phytochemicals (CID_99615, CID_3981360, CID_620012, and CID_11697907). </p>


Author(s):  
Acharya Balkrishna ◽  
Rashmi Mittal ◽  
Vedpriya Arya

Background:: COVID-19 caused by SARS-CoV-2 has been declared as global pandemic by WHO. Comprehensive analysis of this unprecedented outbreak may help to fight against the disease and may play a pivotal role in decreasing the mortality rate linked with it. Papain like protease (PLpro), a multifunctional polyprotein facilitates the replication of SARS-CoV-2 and evades it from the host immunological response by antagonizing cytokines, interferons and may be considered as potential drug target to combat the current pandemic. Methods:: Natural moieties obtained from medicinal plants were analysed for their potency to target PLpro of SARS-CoV-2 by molecular docking study and were compared with synthetic analogs named as remdesivir, chloroquine and favipiravir. The stability of complexes of top hits was analysed by MD Simulation and interaction energy was calculated. Furthermore, average RMSD values were computed and deepsite ligand binding pockets were predicted using Play Molecule. Drug like abilities of these moieties were determined using ADMET and bond distance between the ligand and active site was assessed to predict the strength of interaction. Results:: Nimbocinol (-7.6 Kcal/mol) and sage (-7.3 Kcal/mol) exhibited maximum BA against PLpro SARS-CoV-2 as evident from molecular docking study which was found to be even better than remdesivir (-6.1 Kcal/mol), chloroquine (-5.3 Kcal/mol) and favipiravir (-5.7 Kcal/mol). Both nimbocinol-PLpro and sage-PLpro SARS-CoV-2 complex exhibited stable conformation during MD Simulation of 101ns at 310 K and potential, kinetic and electrostatic interaction energies were computed which was observed to be concordant with results of molecular docking study. RMSD average values were found to be 0.496 ± 0.015 Å and 0.598 ± 0.023 Å for nimbocinol and sage respectively thus revealing that both the deviation and fluctuations during MD Simulation were observed to be least. Deepsite prediction disclosed that both compounds occupied cryptic pockets in receptor and non-bond distance analysis revealed the formation of hydrogen bonds during ligand-receptor interaction. ADMET exploration further validated the drug like properties of these compounds. Conclusion:: Present study revealed that active constituents of Azadirachta indica and Salvia officinalis can be potentially used to target SARS-CoV-2 by hindering its replication process.


Author(s):  
Mubarak A. Alamri ◽  
Ahmed D. Alafnan ◽  
Obaid Afzal ◽  
Alhumaidi B. Alabbas ◽  
Safar M. Alqahtani

Background: The STE20/SPS1-related proline/alanine-rich kinase (SPAK) is a component of WNKSPAK/OSR1 signaling pathway that plays an essential role in blood pressure regulation. The function of SPAK is mediated by its highly conserved C-terminal domain (CTD) that interacts with RFXV/I motifs of upstream activators, WNK kinases, and downstream substrate, cation-chloride cotransporters. Objective: To determine and validate the three-dimensional structure of the CTD of SPAK and to study and analyze its interaction with the RFXV/I motifs. Methods: A homology model of SPAK CTD was generated and validated through multiple approaches. The model was based on utilizing the OSR1 protein kinase as a template. This model was subjected to 100 ns molecular dynamic (MD) simulation to evaluate its dynamic stability. The final equilibrated model was used to dock the RFQV-peptide derived from WNK4 into the primary pocket that was determined based on the homology sequence between human SPAK and OSR1 CTDs. The mechanism of interaction, conformational rearrangement and dynamic stability of the binding of RFQV-peptide to SPAK CTD were characterized by molecular docking and molecular dynamic simulation. Results: The MD simulation suggested that the binding of RFQV induces a large conformational change due to the distribution of salt bridge within the loop regions. These results may help in understanding the relation between the structure and function of SPAK CTD and to support drug design of potential SPAK kinase inhibitors as antihypertensive agents. Conclusion: This study provides deep insight into SPAK CTD structure and function relationship.


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