WHICH IS THE PROTON-SHUTTLE IN ISOXANTHOPTERIN DEAMINASE? QM/MM MD UNDERSTANDING

2013 ◽  
Vol 12 (08) ◽  
pp. 1341002 ◽  
Author(s):  
XIN ZHANG ◽  
MING LEI
Keyword(s):  
Crystal Structure ◽  
Molecular Dynamics ◽  
Hydrogen Bonds ◽  
Proton Transfer ◽  
Glutamic Acid ◽  
Active Site ◽  
Nucleophilic Attack ◽  
Zinc Ions ◽  
Initial Model ◽  
Dynamics Simulations

The deamination process of isoxanthopterin catalyzed by isoxanthopterin deaminase was determined using the combined QM(PM3)/MM molecular dynamics simulations. In this paper, the updated PM3 parameters were employed for zinc ions and the initial model was built up based on the crystal structure. Proton transfer and following steps have been investigated in two paths: Asp336 and His285 serve as the proton shuttle, respectively. Our simulations showed that His285 is more effective than Aap336 in proton transfer for deamination of isoxanthopterin. As hydrogen bonds between the substrate and surrounding residues play a key role in nucleophilic attack, we suggested mutating Thr195 to glutamic acid, which could enhance the hydrogen bonds and help isoxanthopterin get close to the active site. The simulations which change the substrate to pterin 6-carboxylate also performed for comparison. Our results provide reference for understanding of the mechanism of deaminase and for enhancing the deamination rate of isoxanthopterin deaminase.

Mechanisms for the deamination reaction of 8-oxoguanine catalyzed by 8-oxoguanine deaminase: A combined QM/MM molecular dynamics study

2016 ◽  
Vol 15 (08) ◽  
pp. 1650066 ◽  
Author(s):  
Xin Zhang ◽  
Yuan Zhao ◽  
Xinli Duan ◽  
Hui N. Zhang ◽  
Zexing Cao ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Hydrogen Bonds ◽  
Water Molecule ◽  
Proton Transfer ◽  
Enzymatic Catalysis ◽  
Nucleophilic Attack ◽  
Rate Limiting Step ◽  
Repair Activity ◽  
Dynamics Simulations ◽  
Deamination Reaction

The deamination reaction of 8-oxoguanine (8-oxoG) catalyzed by 8-oxoguanine deaminase (8-oxoGD) plays a critically important role in the DNA repair activity for oxidative damage. In order to elucidate the complete enzymatic catalysis mechanism at the stages of 8-oxoguanine binding, departure of 2-hydroxy-1H-purine-6,8(7H,9H)-dione from the active site, and formation of 8-oxoxanthine, extensive combined QM(PM3)/MM molecular dynamics simulations have been performed. Computations show that the rate-limiting step corresponds to the nucleophilic attack from zinc-coordinate hydroxide group to free 8-oxoguanine. Through conformational analyses, we demonstrate that Trp115, Trp123 and Leu119 connect to O8@8-oxoguanine with hydrogen bonds, and we suggest that mutations of tryptophan (115 and 123) to histidine or phenylalanine and mutation of leucine (119) to alanine could potentially lead to a mutant with enhanced activity. On this ground, a proton transfer mechanism for the formation of 8-oxoxanthine was further discussed. Both Glu218 and water molecule could be used as proton shuttles, and water molecule plays a major role in proton transfer in substrate. On the other hand, comparative simulations on the deamination of guanine and isocytosine reveal that, for the helping of hydrogen bonds between O8@8-oxoguanine and enzyme, O8@8-oxoguanine is the fastest to be deaminated among the three substrates which are also supported by the experimental kinetic constants.

Active site gate of M32 carboxypeptidases illuminated by crystal structure and molecular dynamics simulations

2017 ◽  
Vol 1865 (11) ◽  
pp. 1406-1415 ◽  
Author(s):  
Bhaskar Sharma ◽  
Sahayog N. Jamdar ◽  
Biplab Ghosh ◽  
Pooja Yadav ◽  
Ashwani Kumar ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Active Site ◽  
Dynamics Simulations

Molecular dynamics study of active-site interactions with tetracoordinate transients in acetylcholinesterase and its mutants

2001 ◽  
Vol 353 (3) ◽  
pp. 645-653 ◽  
Author(s):  
Istvan J. ENYEDY ◽  
Ildiko M. KOVACH ◽  
Akos BENCSURA
Keyword(s):  
Molecular Dynamics ◽  
Glutamic Acid ◽  
Active Site ◽  
Indole Ring ◽  
Active Site Residues ◽  
Parallel Simulations ◽  
Electrostatic Stabilization ◽  
Carbenium Ion ◽  
Dynamics Simulations

The role of active-site residues in the dealkylation reaction in the PSCS diastereomer of 2-(3,3-dimethylbutyl)methylphosphonofluoridate (soman)-inhibited Torpedo californicaacetylcholinesterase (AChE) was investigated by full-scale molecular dynamics simulations using CHARMM: > 400ps equilibration was followed by 150–200ps production runs with the fully solvated tetracoordinate phosphonate adduct of the wild-type, Trp84Ala and Gly199Gln mutants of AChE. Parallel simulations were carried out with the tetrahedral intermediate formed between serine-200 Oγ of AChE and acetylcholine. We found that the NεH in histidine H+-440 is positioned to protonate the oxygen in choline and thus promote its departure. In contrast, NεH in histidine H+-440 is not aligned for a favourable proton transfer to the pinacolyl O to promote dealkylation, but electrostatic stabilization by histidine H+-440 of the developing anion on the phosphonate monoester occurs. Destabilizing interactions between residues and the alkyl fragment of the inhibitor enforce methyl migration from Cβ to Cα concerted with C—O bond breaking in soman-inhibited AChE. Tryptophan-84, phenyalanine-331 and glutamic acid-199 are within 3.7–3.9 Å (1 Å=10-10 m) from a methyl group in Cβ, 4.5–5.1 Å from Cβ and 4.8–5.8 Å from Cα, and can better stabilize the developing carbenium ion on Cβ than on Cα. The Trp84Ala mutation eliminates interactions between the incipient carbenium ion and the indole ring, but also reduces its interactions with phenylalanine-331 and aspartic acid-72. Tyrosine-130 promotes dealkylation by interacting with the indole ring of tryptophan-84. Glutamic acid-443 can influence the orientation of active-site residues through tyrosine-421, tyrosine-442 and histidine-440 in soman-inhibited AChE, and thus facilitate dealkylation.

scholarly journals Deciphering the Binding Mechanism of Dexamethasone Against SARS-CoV-2 Main Protease: Computational Molecular Modelling Approach

2020 ◽  
Author(s):  
Shafi Ullah Khan ◽  
Thet.thet Htar
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Active Site ◽  
Binding Mechanism ◽  
Protein Targets ◽  
High Affinity ◽  
Main Protease ◽  
Dynamics Simulations ◽  
Covalent Inhibitor ◽  
Modelling Approach

<p>At present, there are no proven agents for the treatment of 2019 coronavirus disease (COVID-19). The available evidence has not allowed guidelines to clearly recommend any drugs outside the context of clinical trials. One of the most important SARS-CoV-2 protein targets for therapeutics is the 3C-like protease (main protease, Mpro). Here in this study we utilize the recently published 6W63 crystal structure of Mpro complexed with a non-covalent inhibitor X77. Various docking methods FRED, HYBRID, CDOCKER and LEADFINDER tools were benchmark to optimally re-dock the co-crystal ligand within the active site of SARS-COV-2 Mpro. This study was restricted to molecular docking without validation by molecular dynamics simulations. CDOCKER was found to depict the exact binding of co-crystal ligand having lowest RMSD of less than 2 A. Interactions with the SARS-COV-2 Mpro may play a key role in fighting against viruses. Dexamethasone was found to bind with a high affinity to the same sites of the SARS-COV-2 Mpro than the Remdesivir. Dexamethasone was forming six hydrogen bonds compared to the three hydrogen bonds formed by Remdesivir within the active site of SARS-COV-2 Mpro. LEU141, GLY143, HIS163, GLU166, GLN192 were the key amino acid residue of SAR-COV-2 Mpro involved in stabilizing the complex between Dexamethasone and SARS-COV-2 Mpro. The results suggest the effectiveness of Dexamethasone as potent drugs against SARS-CoV-2 since it bind tightly to its Mpro. In addition, the results also suggest that dexamethasone as top antiviral treatments option than the Remdesivir with high potential to fight the SARS-CoV-2.</p>

Molecular Dynamics simulations indicate solvation and stability of single-strand RNA at the air/ice interface, supporting a primordial RNA world on Ice

2020 ◽  
Author(s):  
Steven Neshyba ◽  
Ivan Gladich ◽  
Penny Rowe ◽  
Maggie Berrens ◽  
Rodolfo Pereyra
Keyword(s):  
Molecular Dynamics ◽  
Hydrogen Bonds ◽  
Molecular Dynamics Simulations ◽  
Rna World ◽  
Nucleophilic Attack ◽  
Solvent Water ◽  
Phosphate Diester ◽  
World Hypothesis ◽  
Dynamics Simulations ◽  
Rna World Hypothesis

&lt;p&gt;Outstanding questions about the RNA world hypothesis for the emergence of life on Earth concern the stability and self-replication of prebiotic aqueous RNA. Recent experimental work has suggested that solid substrates and low temperatures could help resolve these issues. Here, we use classical molecular dynamics simulations to explore the possibility that the substrate is ice itself. We find that at -20 C, a quasi-liquid layer at the air/ice interface partially solvates a short (8-nucleotide) RNA strand such that the phosphate backbone anchors to the underlying crystalline ice structure though long-lived hydrogen bonds. The hydrophobic bases, meanwhile, are seen to migrate toward the outermost layer, exposed to air. Our simulations also reveal two key kinetic differences with respect to aqueous RNA. First, hydrogen bonds between solvent water molecules and phosphate diester moieties, believed to shield the RNA from hydrolysis, are much longer-lived for RNA on ice, compared to aqueous RNA at the same temperature. Second, contact between solvent water and ribose 2-OH&amp;#8217; groups, considered a precursor to nucleophilic attack by deprotonated 2-OH&amp;#8217; on the phosphate diester, is significantly less frequent for RNA on ice. Both differences point to lower susceptibility to hydrolysis of RNA on ice, and therefore increased opportunities for polymerization and self-copying compared to aqueous RNA. Moreover, exposure of hydrophobic bases at the air/ice interface offers opportunities for reaction that are not readily available to aqueous RNA (e.g., base-pairing reaction with free nucleotides diffusing across the air/ice interface). These findings thus offer the possibility of a role for an ancient RNA world on ice distinct from that considered in extant elaborations of the RNA world hypothesis. This work is, to the best of our knowledge, the first molecular dynamics study of RNA on ice.&lt;/p&gt;

scholarly journals Deciphering the Binding Mechanism of Dexamethasone Against SARS-CoV-2 Main Protease: Computational Molecular Modelling Approach

2020 ◽  
Author(s):  
Shafi Ullah Khan ◽  
Thet.thet Htar
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Active Site ◽  
Binding Mechanism ◽  
Protein Targets ◽  
High Affinity ◽  
Main Protease ◽  
Dynamics Simulations ◽  
Covalent Inhibitor ◽  
Modelling Approach

<p>At present, there are no proven agents for the treatment of 2019 coronavirus disease (COVID-19). The available evidence has not allowed guidelines to clearly recommend any drugs outside the context of clinical trials. One of the most important SARS-CoV-2 protein targets for therapeutics is the 3C-like protease (main protease, Mpro). Here in this study we utilize the recently published 6W63 crystal structure of Mpro complexed with a non-covalent inhibitor X77. Various docking methods FRED, HYBRID, CDOCKER and LEADFINDER tools were benchmark to optimally re-dock the co-crystal ligand within the active site of SARS-COV-2 Mpro. This study was restricted to molecular docking without validation by molecular dynamics simulations. CDOCKER was found to depict the exact binding of co-crystal ligand having lowest RMSD of less than 2 A. Interactions with the SARS-COV-2 Mpro may play a key role in fighting against viruses. Dexamethasone was found to bind with a high affinity to the same sites of the SARS-COV-2 Mpro than the Remdesivir. Dexamethasone was forming six hydrogen bonds compared to the three hydrogen bonds formed by Remdesivir within the active site of SARS-COV-2 Mpro. LEU141, GLY143, HIS163, GLU166, GLN192 were the key amino acid residue of SAR-COV-2 Mpro involved in stabilizing the complex between Dexamethasone and SARS-COV-2 Mpro. The results suggest the effectiveness of Dexamethasone as potent drugs against SARS-CoV-2 since it bind tightly to its Mpro. In addition, the results also suggest that dexamethasone as top antiviral treatments option than the Remdesivir with high potential to fight the SARS-CoV-2.</p>

scholarly journals Combined Use of Structure Analysis, Studies of Molecular Association in Solution, and Molecular Modelling to Understand the Different Propensities of Dihydroxybenzoic Acids to Form Solid Phases

Pharmaceutics ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 734
Author(s):  
Aija Trimdale ◽  
Anatoly Mishnev ◽  
Agris Bērziņš
Keyword(s):  
Crystal Structure ◽  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Structure Analysis ◽  
Crystal Structure Analysis ◽  
Molecular Association ◽  
Hydroxyl Groups ◽  
Solid Phases ◽  
Solvent Molecules ◽  
Dynamics Simulations

The arrangement of hydroxyl groups in the benzene ring has a significant effect on the propensity of dihydroxybenzoic acids (diOHBAs) to form different solid phases when crystallized from solution. All six diOHBAs were categorized into distinctive groups according to the solid phases obtained when crystallized from selected solvents. A combined study using crystal structure and molecule electrostatic potential surface analysis, as well as an exploration of molecular association in solution using spectroscopic methods and molecular dynamics simulations were used to determine the possible mechanism of how the location of the phenolic hydroxyl groups affect the diversity of solid phases formed by the diOHBAs. The crystal structure analysis showed that classical carboxylic acid homodimers and ring-like hydrogen bond motifs consisting of six diOHBA molecules are prominently present in almost all analyzed crystal structures. Both experimental spectroscopic investigations and molecular dynamics simulations indicated that the extent of intramolecular bonding between carboxyl and hydroxyl groups in solution has the most significant impact on the solid phases formed by the diOHBAs. Additionally, the extent of hydrogen bonding with solvent molecules and the mean lifetime of solute–solvent associates formed by diOHBAs and 2-propanol were also investigated.

scholarly journals The structure of the metallo-β-lactamase VIM-2 in complex with a triazolylthioacetamide inhibitor

2016 ◽  
Vol 72 (11) ◽  
pp. 813-819 ◽  
Author(s):  
Tony Christopeit ◽  
Ke-Wu Yang ◽  
Shao-Kang Yang ◽  
Hanna-Kirsti S. Leiros
Keyword(s):  
Public Health ◽  
Crystal Structure ◽  
Active Site ◽  
Drug Target ◽  
Zinc Ions ◽  
Clinical Use ◽  
Global Public Health ◽  
Promising Strategy ◽  
Conserved Residue ◽  
Substrate Spectrum

The increasing number of pathogens expressing metallo-β-lactamases (MBLs), and in this way achieving resistance to β-lactam antibiotics, is a significant threat to global public health. A promising strategy to treat such resistant pathogens is the co-administration of MBL inhibitors together with β-lactam antibiotics. However, an MBL inhibitor suitable for clinical use has not yet been identified. Verona integron-encoded metallo-β-lactamase 2 (VIM-2) is a widespread MBL with a broad substrate spectrum and hence is an interesting drug target for the treatment of β-lactam-resistant infections. In this study, three triazolylthioacetamides were tested as inhibitors of VIM-2. One of the tested compounds showed clear inhibition of VIM-2, with an IC50of 20 µM. The crystal structure of the inhibitor in complex with VIM-2 was obtained by DMSO-free co-crystallization and was solved at a resolution of 1.50 Å. To our knowledge, this is the first structure of a triazolylthioacetamide inhibitor in complex with an MBL. Analysis of the structure shows that the inhibitor binds to the two zinc ions in the active site of VIM-2 and revealed detailed information on the interactions involved. Furthermore, the crystal structure showed that binding of the inhibitor induced a conformational change of the conserved residue Trp87.

scholarly journals Car–Parrinello and path integral molecular dynamics study of the intramolecular hydrogen bonds in the crystals of benzoylacetone and dideuterobenzoylacetone

2014 ◽  
Vol 16 (42) ◽  
pp. 23026-23037 ◽  
Author(s):  
Piotr Durlak ◽  
Zdzisław Latajka
Keyword(s):  
Molecular Dynamics ◽  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Ab Initio ◽  
Path Integral ◽  
Molecular Crystal ◽  
Short Hydrogen Bond ◽  
Deuterated Analogue ◽  
Dynamics Simulations ◽  
Intramolecular Hydrogen

The dynamics of the intramolecular short hydrogen bond in the molecular crystal of benzoylacetone and its deuterated analogue are investigated using ab initio molecular dynamics simulations.

scholarly journals Cavity hydration dynamics in cytochrome c oxidase and functional implications

2017 ◽  
Vol 114 (42) ◽  
pp. E8830-E8836 ◽  
Author(s):  
Chang Yun Son ◽  
Arun Yethiraj ◽  
Qiang Cui
Keyword(s):  
Molecular Dynamics ◽  
Free Energy ◽  
Proton Transfer ◽  
Molecular Dynamics Simulations ◽  
Transmembrane Protein ◽  
Wetting Transition ◽  
Protonation State ◽  
Hydration Level ◽  
Level Change ◽  
Dynamics Simulations

Cytochrome c oxidase (CcO) is a transmembrane protein that uses the free energy of O2 reduction to generate the proton concentration gradient across the membrane. The regulation of competitive proton transfer pathways has been established to be essential to the vectorial transport efficiency of CcO, yet the underlying mechanism at the molecular level remains lacking. Recent studies have highlighted the potential importance of hydration-level change in an internal cavity that connects the proton entrance channel, the site of O2 reduction, and the putative proton exit route. In this work, we use atomistic molecular dynamics simulations to investigate the energetics and timescales associated with the volume fluctuation and hydration-level change in this central cavity. Extensive unrestrained molecular dynamics simulations (accumulatively ∼4 μs) and free energy computations for different chemical states of CcO support a model in which the volume and hydration level of the cavity are regulated by the protonation state of a propionate group of heme a3 and, to a lesser degree, the redox state of heme a and protonation state of Glu286. Markov-state model analysis of ∼2-μs trajectories suggests that hydration-level change occurs on the timescale of 100–200 ns before the proton-loading site is protonated. The computed energetic and kinetic features for the cavity wetting transition suggest that reversible hydration-level change of the cavity can indeed be a key factor that regulates the branching of proton transfer events and therefore contributes to the vectorial efficiency of proton transport.

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