Enhancing Paraoxon Binding to Organophosphorus Hydrolase Active Site

Organophosphorus (OP) compounds are among the most toxic of chemical substances and widely used as insecticides, pesticides, and chemical warfare agents. The most important enzyme inhibited by OP compounds is acetylcholinesterase (AChe). Inactivation of AChe function results in the accumulation of neurotransmitter, leading to death due to serious respiratory disorders. Organophosphorus hydrolase (OPH), also called phosphotriesterase, is a homo-dimeric metalloenzyme that can hydrolyze various OP agents in the circulatory system, resulting in products that are generally of reduced toxicity. The best OPH substrate found to date is the insecticide diethyl p-nitrophenyl phosphate (paraoxon). Most structural and kinetic studies assume that the binding orientation of paraoxon is identical to that of diethyl 4-methylbenzylphosphonate, which is the only substrate analog co-crystallized with OPH. In the current work, we used a combined docking and molecular dynamics (MD) approach to predict the likely binding mode of paraoxon in the OPH active site. We identified a potential binding mode of paraoxon that does not match the binding mode of diethyl 4-methylbenzylphosphonate. Then, we used the predicted binding mode to run MD simulations on the wild type (WT) OPH complexed with paraoxon, and OPH mutants complexed with paraoxon. Additionally, we identified 3 hot-spot residues (D253, H254, and I255) involved in the stability of the OPH active site. To further assess these predictions, we then experimentally assayed single and double mutants involving these residues (D253E, H254S, I255S, D253E-H254R and D253E-I255G) for hydrolytic activity against paraoxon. Computational structural analysis of protein-substrate dynamics shows different hydrogen bonding profiles for mutants involving D253 (D253E, D253E-H254R, and D253E-I255G) compared to WT OPH. Additionally, the binding free energy calculations and the experimental kinetics (particularly, kcat and KM) of the reactions between each OPH mutant and paraoxon show that mutated forms D253E, D253E-H254R, and D253E-I255G exhibit enhanced activity over WT OPH. Interestingly, our experimental results show that the activity of the double mutant D253E-H254R increased by 19-fold compared to WT OPH.

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Enhancing Paraoxon Binding to Organophosphorus Hydrolase Active Site

10.26434/chemrxiv.13930874 ◽

2021 ◽

Author(s):

Léa El Khoury ◽

David Mobley ◽

Dongmei Ye ◽

Susan Rempe

Keyword(s):

Active Site ◽

Binding Free Energy ◽

Hot Spot ◽

Circulatory System ◽

Kinetic Studies ◽

Md Simulations ◽

Binding Mode ◽

Hydrolytic Activity ◽

Free Energy Calculations ◽

Organophosphorus Hydrolase

Organophosphorus (OP) compounds are among the most toxic of chemical substances and widely used as insecticides, pesticides, and chemical warfare agents. The most important enzyme inhibited by OP compounds is acetylcholinesterase (AChe). Inactivation of AChe function results in the accumulation of neurotransmitter, leading to death due to serious respiratory disorders. Organophosphorus hydrolase (OPH), also called phosphotriesterase, is a homo-dimeric metalloenzyme that can hydrolyze various OP agents in the circulatory system, resulting in products that are generally of reduced toxicity. The best OPH substrate found to date is the insecticide diethyl p-nitrophenyl phosphate (paraoxon). Most structural and kinetic studies assume that the binding orientation of paraoxon is identical to that of diethyl 4-methylbenzylphosphonate, which is the only substrate analog co-crystallized with OPH. In the current work, we used a combined docking and molecular dynamics (MD) approach to predict the likely binding mode of paraoxon in the OPH active site. We identified a potential binding mode of paraoxon that does not match the binding mode of diethyl 4-methylbenzylphosphonate. Then, we used the predicted binding mode to run MD simulations on the wild type (WT) OPH complexed with paraoxon, and OPH mutants complexed with paraoxon. Additionally, we identified 3 hot-spot residues (D253, H254, and I255) involved in the stability of the OPH active site. To further assess these predictions, we then experimentally assayed single and double mutants involving these residues (D253E, H254S, I255S, D253E-H254R and D253E-I255G) for hydrolytic activity against paraoxon. Computational structural analysis of protein-substrate dynamics shows different hydrogen bonding profiles for mutants involving D253 (D253E, D253E-H254R, and D253E-I255G) compared to WT OPH. Additionally, the binding free energy calculations and the experimental kinetics (particularly, kcat and KM) of the reactions between each OPH mutant and paraoxon show that mutated forms D253E, D253E-H254R, and D253E-I255G exhibit enhanced activity over WT OPH. Interestingly, our experimental results show that the activity of the double mutant D253E-H254R increased by 19-fold compared to WT OPH.

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Targeting Peptidyl-prolyl Cis-trans Isomerase NIMA-interacting 1: A Structure-based Virtual Screening Approach to Find Novel Inhibitors

Current Computer - Aided Drug Design ◽

10.2174/1573409915666191025114009 ◽

2020 ◽

Vol 16 (5) ◽

pp. 605-617 ◽

Cited By ~ 1

Author(s):

Kauê Santana da Costa ◽

João M. Galúcio ◽

Deivid Almeida de Jesus ◽

Guelber Cardoso Gomes ◽

Anderson Henrique Lima e Lima ◽

...

Keyword(s):

Inhibitory Activity ◽

Binding Free Energy ◽

Md Simulations ◽

Binding Mode ◽

Free Energy Calculations ◽

Pentacyclic Triterpenoids ◽

Substrate Peptide ◽

Molecular Mechanism Of Action ◽

Structural Insights ◽

Virtual Screening Approach

Background : Peptidyl-prolyl cis-trans isomerase NIMA-interacting 1 (Pin1) is an enzyme that isomerizes phosphorylated serine or threonine motifs adjacent to proline residues. Pin1 has important roles in several cellular signaling pathways, consequently impacting the development of multiple types of cancers. Methods: Based on the previously reported inhibitory activity of pentacyclic triterpenoids isolated from the gum resin of Boswellia genus against Pin1, we designed a computational experiment using molecular docking, pharmacophore filtering, and structural clustering allied to molecular dynamics (MD) simulations and binding free energy calculations to explore the inhibitory activity of new triterpenoids against Pin1 structure. Results: Here, we report different computational evidence that triterpenoids from neem (Azadirachta indica A. Juss), such as 6-deacetylnimbinene, 6-Oacetylnimbandiol, and nimbolide, replicate the binding mode of the Pin1 substrate peptide, interacting with high affinity with the binding site and thus destabilizing the Pin1 structure. Conclusion: Our results are supported by experimental data, and provide interesting structural insights into their molecular mechanism of action, indicating that their structural scaffolds could be used as a start point to develop new inhibitors against Pin1.

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Insight Derived from Molecular Docking and Molecular Dynamics Simulations into the Binding Interactions Between HIV-1 Protease Inhibitors and SARS-CoV-2 3CLpro

10.26434/chemrxiv.11932995.v1 ◽

2020 ◽

Cited By ~ 3

Author(s):

peng sang ◽

Shuhui Tian ◽

Zhaohui Meng ◽

Liquan Yang

Keyword(s):

Molecular Docking ◽

Protease Inhibitors ◽

Binding Affinity ◽

Proteinase Inhibitors ◽

Binding Free Energy ◽

Md Simulations ◽

Respiratory Illness ◽

Free Energy Calculations ◽

Binding Interactions ◽

Hiv 1

A novel severe acute respiratory syndrome coronavirus (SARS-CoV-2) was identified from respiratory illness patients in Wuhan, Hubei Province, China, which has recently emerged as a serious threat to the world public health. Hower, no approved drugs have been found to effectively inhibit the virus. Since it has been reported that the HIV-1 protease inhibitors can be used as anti-SARS drugs by tegarting SARS-CoV 3CLpro, we choose six approved anti-HIV-1 drugs to investigate their binding interactions between 3CLpro, and to evaluate their potential to become clinical drugs for the new coronavirus pneumonia (COVID19) caused by SARS-CoV-2 infection. The molecular docking results indicate that, the 3CLpro of SARS-CoV-2 has a higher binding affinity for all the studied inhibitors than its SARS homologue. Two docking complexes (indinavir and darunavir) with high docking scores were futher subjected to MM-PBSA binding free energy calculations to detail the molecular interactions between these two proteinase inhibitors and the 3CLpro. Our results show that darunavir has the best binding affinity with SARS-CoV-2 and SARS-CoV 3CLpro among all inhibitors, indicating it has the potential to become an anti-COVID-19 clinical drug. The likely reason behind the increased binding affinity of HIV-1 protease inhibitors toward SARS-CoV2 3CLpro than that of SARS-CoV were investigated by MD simulations. Our study provides insight into the possible role of structural flexibility during interactions between 3CLpro and inhibitors, and sheds light on the structure-based design of anti-COVID-19 drugs targeting the SARS-CoV-2 3CLpro. <div> </div>

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Insight Derived from Molecular Docking and Molecular Dynamics Simulations into the Binding Interactions Between HIV-1 Protease Inhibitors and SARS-CoV-2 3CLpro

10.26434/chemrxiv.11932995 ◽

2020 ◽

Cited By ~ 5

Author(s):

peng sang ◽

Shuhui Tian ◽

Zhaohui Meng ◽

Liquan Yang

Keyword(s):

Molecular Docking ◽

Protease Inhibitors ◽

Binding Affinity ◽

Proteinase Inhibitors ◽

Binding Free Energy ◽

Md Simulations ◽

Respiratory Illness ◽

Free Energy Calculations ◽

Binding Interactions ◽

Hiv 1

A novel severe acute respiratory syndrome coronavirus (SARS-CoV-2) was identified from respiratory illness patients in Wuhan, Hubei Province, China, which has recently emerged as a serious threat to the world public health. Hower, no approved drugs have been found to effectively inhibit the virus. Since it has been reported that the HIV-1 protease inhibitors can be used as anti-SARS drugs by tegarting SARS-CoV 3CLpro, we choose six approved anti-HIV-1 drugs to investigate their binding interactions between 3CLpro, and to evaluate their potential to become clinical drugs for the new coronavirus pneumonia (COVID19) caused by SARS-CoV-2 infection. The molecular docking results indicate that, the 3CLpro of SARS-CoV-2 has a higher binding affinity for all the studied inhibitors than its SARS homologue. Two docking complexes (indinavir and darunavir) with high docking scores were futher subjected to MM-PBSA binding free energy calculations to detail the molecular interactions between these two proteinase inhibitors and the 3CLpro. Our results show that darunavir has the best binding affinity with SARS-CoV-2 and SARS-CoV 3CLpro among all inhibitors, indicating it has the potential to become an anti-COVID-19 clinical drug. The likely reason behind the increased binding affinity of HIV-1 protease inhibitors toward SARS-CoV2 3CLpro than that of SARS-CoV were investigated by MD simulations. Our study provides insight into the possible role of structural flexibility during interactions between 3CLpro and inhibitors, and sheds light on the structure-based design of anti-COVID-19 drugs targeting the SARS-CoV-2 3CLpro. <div> </div>

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Calculation of free energy changes due to mutations from alchemical free energy simulations

Journal of Theoretical and Computational Chemistry ◽

10.1142/s0219633615500236 ◽

2015 ◽

Vol 14 (03) ◽

pp. 1550023 ◽

Cited By ~ 3

Author(s):

M. Harunur Rashid ◽

Germano Heinzelmann ◽

Serdar Kuyucak

Keyword(s):

Free Energy ◽

Fundamental Problem ◽

Binding Free Energy ◽

Computational Design ◽

Md Simulations ◽

Binding Mode ◽

Free Energy Calculations ◽

Energy Calculations ◽

Energy Simulations ◽

Alchemical Free Energy

How a mutation affects the binding free energy of a ligand is a fundamental problem in molecular biology/biochemistry with many applications in pharmacology and biotechnology, e.g. design of drugs and enzymes. Free energy change due to a mutation can be determined most accurately by performing alchemical free energy calculations in molecular dynamics (MD) simulations. Here we discuss the necessary conditions for success of free energy calculations using toxin peptides that bind to ion channels as examples. We show that preservation of the binding mode is an essential requirement but this condition is not always satisfied, especially when the mutation involves a charged residue. Otherwise problems with accuracy of results encountered in mutation of charged residues can be overcome by performing the mutation on the ligand in the binding site and bulk simultaneously and in the same system. The proposed method will be useful in improving the affinity and selectivity profiles of drug leads and enzymes via computational design and protein engineering.

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Binding mode and free energy prediction of fisetin/β-cyclodextrin inclusion complexes

Beilstein Journal of Organic Chemistry ◽

10.3762/bjoc.10.296 ◽

2014 ◽

Vol 10 ◽

pp. 2789-2799 ◽

Cited By ~ 30

Author(s):

Bodee Nutho ◽

Wasinee Khuntawee ◽

Chompoonut Rungnim ◽

Piamsook Pongsawasdi ◽

Peter Wolschann ◽

...

Keyword(s):

Free Energy ◽

Molecular Docking ◽

Phenyl Ring ◽

Binding Free Energy ◽

Md Simulations ◽

Binding Mode ◽

Free Energy Calculations ◽

Energy Prediction ◽

Theoretical Approaches ◽

Preferential Binding

In the present study, our aim is to investigate the preferential binding mode and encapsulation of the flavonoid fisetin in the nano-pore of β-cyclodextrin (β-CD) at the molecular level using various theoretical approaches: molecular docking, molecular dynamics (MD) simulations and binding free energy calculations. The molecular docking suggested four possible fisetin orientations in the cavity through its chromone or phenyl ring with two different geometries of fisetin due to the rotatable bond between the two rings. From the multiple MD results, the phenyl ring of fisetin favours its inclusion into the β-CD cavity, whilst less binding or even unbinding preference was observed in the complexes where the larger chromone ring is located in the cavity. All MM- and QM-PBSA/GBSA free energy predictions supported the more stable fisetin/β-CD complex of the bound phenyl ring. Van der Waals interaction is the key force in forming the complexes. In addition, the quantum mechanics calculations with M06-2X/6-31G(d,p) clearly showed that both solvation effect and BSSE correction cannot be neglected for the energy determination of the chosen system.

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Automated, Accurate, and Scalable Relative Protein-Ligand Binding Free Energy Calculations using Lambda Dynamics

10.26434/chemrxiv.12781310.v1 ◽

2020 ◽

Author(s):

E. Prabhu Raman ◽

Thomas J. Paul ◽

Ryan L. Hayes ◽

Charles L. Brooks III

Keyword(s):

Free Energy ◽

Ligand Binding ◽

Binding Affinity ◽

Binding Free Energy ◽

Computational Cost ◽

Combinatorial Libraries ◽

Free Energy Calculations ◽

Lead Optimization ◽

Efficient Estimation ◽

Lead Compound

Accurate predictions of changes to protein-ligand binding affinity in response to chemical modifications are of utility in small molecule lead optimization. Relative free energy perturbation (FEP) approaches are one of the most widely utilized for this goal, but involve significant computational cost, thus limiting their application to small sets of compounds. Lambda dynamics, also rigorously based on the principles of statistical mechanics, provides a more efficient alternative. In this paper, we describe the development of a workflow to setup, execute, and analyze Multi-Site Lambda Dynamics (MSLD) calculations run on GPUs with CHARMm implemented in BIOVIA Discovery Studio and Pipeline Pilot. The workflow establishes a framework for setting up simulation systems for exploratory screening of modifications to a lead compound, enabling the calculation of relative binding affinities of combinatorial libraries. To validate the workflow, a diverse dataset of congeneric ligands for seven proteins with experimental binding affinity data is examined. A protocol to automatically tailor fit biasing potentials iteratively to flatten the free energy landscape of any MSLD system is developed that enhances sampling and allows for efficient estimation of free energy differences. The protocol is first validated on a large number of ligand subsets that model diverse substituents, which shows accurate and reliable performance. The scalability of the workflow is also tested to screen more than a hundred ligands modeled in a single system, which also resulted in accurate predictions. With a cumulative sampling time of 150ns or less, the method results in average unsigned errors of under 1 kcal/mol in most cases for both small and large combinatorial libraries. For the multi-site systems examined, the method is estimated to be more than an order of magnitude more efficient than contemporary FEP applications. The results thus demonstrate the utility of the presented MSLD workflow to efficiently screen combinatorial libraries and explore chemical space around a lead compound, and thus are of utility in lead optimization.

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Faculty Opinions recommendation of Computational prediction of structure, substrate binding mode, mechanism, and rate for a malaria protease with a novel type of active site.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1024182.290792 ◽

2005 ◽

Author(s):

Arieh Warshel

Keyword(s):

Active Site ◽

Substrate Binding ◽

Computational Prediction ◽

Binding Mode

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In Silico Exploration of Phytoconstituents From Phyllanthus emblica and Aegle marmelos as Potential Therapeutics Against SARS-CoV-2 RdRp

Bioinformatics and Biology Insights ◽

10.1177/11779322211027403 ◽

2021 ◽

Vol 15 ◽

pp. 117793222110274

Author(s):

Khushboo Pandey ◽

Kiran Bharat Lokhande ◽

K Venkateswara Swamy ◽

Shuchi Nagar ◽

Manjusha Dake

Keyword(s):

Molecular Docking ◽

Binding Affinity ◽

Simulation Analysis ◽

Binding Free Energy ◽

Free Energy Calculations ◽

Molecular Field ◽

Hydroxyl Groups ◽

Phyllanthus Emblica ◽

Inhibitory Potential ◽

Novel Drug

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) worldwide has increased the importance of computational tools to design a drug or vaccine in reduced time with minimum risk. Earlier studies have emphasized the important role of RNA-dependent RNA polymerase (RdRp) in SARS-CoV-2 replication as a potential drug target. In our study, comprehensive computational approaches were applied to identify potential compounds targeting RdRp of SARS-CoV-2. To study the binding affinity and stability of the phytocompounds from Phyllanthus emblica and Aegel marmelos within the defined binding site of SARS-CoV-2 RdRp, they were subjected to molecular docking, 100 ns molecular dynamics (MD) simulation followed by post-simulation analysis. Furthermore, to assess the importance of features involved in the strong binding affinity, molecular field-based similarity analysis was performed. Based on comparative molecular docking and simulation studies of the selected phytocompounds with SARS-CoV-2 RdRp revealed that EBDGp possesses a stronger binding affinity (−23.32 kcal/mol) and stability than other phytocompounds and reference compound, Remdesivir (−19.36 kcal/mol). Molecular field-based similarity profiling has supported our study in the validation of the importance of the presence of hydroxyl groups in EBDGp, involved in increasing its binding affinity toward SARS-CoV-2 RdRp. Molecular docking and dynamic simulation results confirmed that EBDGp has better inhibitory potential than Remdesivir and can be an effective novel drug for SARS-CoV-2 RdRp. Furthermore, binding free energy calculations confirmed the higher stability of the SARS-CoV-2 RdRp-EBDGp complex. These results suggest that the EBDGp compound may emerge as a promising drug against SARS-CoV-2 and hence requires further experimental validation.

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