Multi-Pharmacophore Modeling of Caspase-3 Inhibitors using Crystal, Dock and Flexible Conformation Schemes

2018 ◽  
Vol 21 (1) ◽  
pp. 26-40 ◽  
Author(s):  
Sivakumar Prasanth Kumar ◽  
Prakash Chandra Jha
Keyword(s):  
Crystal Structure ◽  
Caspase 3 ◽  
Empirical Relationship ◽  
Binding Mode ◽  
Pharmacophore Modeling ◽  
Validation Dataset ◽  
Pharmacophore Hypotheses ◽  
Database Screening ◽  
Modeling Strategy ◽  
Pharmacophore Models

Aim and Objective: Numerous caspase-3 drug discovery projects were found to have relied on single receptor as the template to recognize most promising small molecule candidates using docking approach. Alternatively, some researchers were contingent upon ligand-based alignment to build up an empirical relationship between ligand functional groups and caspase-3 inhibitory activity quantitatively. To connect both caspase-3 receptor details and its inhibitors chemical functionalities, this study was undertaken to develop receptor- and ligand-pharmacophore models based on different conformational schemes. Material and Methods: A multi-pharmacophore modeling strategy is carried out based on three conformational schemes of pharmacophore hypothesis generation to screen caspase-3 inhibitors from database. The schemes include (i) flexible (conformations unrestricted or flexible during pharmacophore mapping), (ii) dock (conformations obtained using FlexX docking method) and (iii) crystal (extracted from multiple caspase-3-ligand complexes from PDB repository) conformations of query ligands. The pharmacophore models developed using these conformational schemes were then used to identify probable caspase-3 inhibitors from ZINC database. Results: We noticed better sensitivity with good specificity measures returned by candidate pharmacophore hypotheses across each conformation type and recognized crucial pharmacophore features that enable caspase-3 binding. Pharmacophore modeling based on flexible conformational scheme indicated that the crystal structure 3KJF (AAAADH) is the best receptor structure to perform receptor-based pharmacophore screening of caspase-3 inhibitors. When multiple crystal structures were included, the hypothesis (HAAA) is more generalized. Superimposition of multiple co-crystal ligands from various caspase-3 PDB entries in crystallographic binding mode revealed similar hypothesis (HAAA). Further, FlexX-guided dock conformations of validation dataset showed that the crystal structure 1RE1 is the best-suited for dock-based pharmacophore models. Database screening using these pharmacophore hypotheses identified N'-[6-(benzimidazol-1-yl)-5-nitro-pyrimidin-4-yl]-4 methylbenzenesulfonohydrazide and 2-nitro-N'-[5-nitro-6-[N'-(p-tolylsulfonyl)hydrazino]pyrimidin-4- yl]benzohydrazide as the probable caspase-3 inhibitors. Conclusion: N'-[6-(benzimidazol-1-yl)-5-nitro-pyrimidin-4-yl]-4 methylbenzenesulfonohydrazide and 2-nitro-N'-[5-nitro-6-[N'-(p-tolylsulfonyl)hydrazino]pyrimidin-4-yl]benzohydrazide may be tested for caspase-3 inhibition. We believe that potential caspase-3 inhibitors can be recognized efficiently by adapting multi-pharmacophore models in database screening.

Ruthenium(II) Complexes Bearing Thioether-Appended α- Iminopyridine Ligands: Arene Precursors Permit Access to K2-N,N and K3-N,N,S Complexes

2019 ◽  
Author(s):  
Victoria A. Ternes ◽  
Hannah A. Morgan ◽  
Austin P. Lanquist ◽  
Michael P. Murray ◽  
Bradley Wile
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Strong Field ◽  
Active Role ◽  
Binding Mode ◽  
Phenethyl Alcohol ◽  
Ru Complexes

Herein we report the preparation of a series of Ru(II) complexes featuring alpha-iminopyridine ligands bearing thioether functionality (NNS<sup>R</sup>, where R = Me, CH<sub>2</sub>Ph, Ph). Metallation using (<i>p</i> cymene)RuCl dimer permits access to (k<sup>2</sup>-N,N)Ru complexes in which the thioether moiety remains uncoordinated. In the presence of a strong field ligand such as acetonitrile or triphenylphosphine, the p-cymene moiety is displaced, and the ligand adopts a k<sup>3</sup>-N,N,S binding mode. These complexes are characterized using a combination of solution and solid state methods, including the crystal structure of [(NNS<sup>Me</sup>)Ru(NCMe)<sub>2</sub>Cl]Cl. The k<sup>2</sup>-N,N Ru(II) complexes are shown to serve as efficient precatalysts for the oxidation of sec-phenethyl alcohol at 5 mol% loadings, using a variety of external oxidants and solvents. The complex bearing an S-Ph donor was found to be the most active of those surveyed, suggesting that the thioether donor plays an active role in catalyst speciation for this transformation.

scholarly journals Discovery of novel potential KIT inhibitors for the treatment of gastrointestinal stromal tumor

2021 ◽  
Vol 16 (1) ◽  
pp. 303-310
Author(s):  
Lili Jiang ◽  
Zhongmin Zhang ◽  
Zhen Wang ◽  
Yong Liu
Keyword(s):  
Molecular Docking ◽  
Gastrointestinal Stromal Tumor ◽  
Pharmacophore Modeling ◽  
Stromal Tumor ◽  
Strong Hydrogen Bond ◽  
Ligand Complex ◽  
Hydrogen Bond Interaction ◽  
Mutant Proteins ◽  
Docking Simulations ◽  
Pharmacophore Models

Abstract Numerous inhibitors of tyrosine-protein kinase KIT, a receptor tyrosine kinase, have been explored as a viable therapy for the treatment of gastrointestinal stromal tumor (GIST). However, drug resistance due to acquired mutations in KIT makes these drugs almost useless. The present study was designed to screen the novel inhibitors against the activity of the KIT mutants through pharmacophore modeling and molecular docking. The best two pharmacophore models were established using the KIT mutants’ crystal complexes and were used to screen the new compounds with possible KIT inhibitory activity against both activation loop and ATP-binding mutants. As a result, two compounds were identified as potential candidates from the virtual screening, which satisfied the potential binding capabilities, molecular modeling characteristics, and predicted absorption, distribution, metabolism, excretion, toxicity (ADMET) properties. Further molecular docking simulations showed that two compounds made strong hydrogen bond interaction with different KIT mutant proteins. Our results indicated that pharmacophore models based on the receptor–ligand complex had excellent ability to screen KIT inhibitors, and two compounds may have the potential to develop further as the future KIT inhibitors for GIST treatment.

scholarly journals Crystal structures of Ca2+–calmodulin bound to NaV C-terminal regions suggest role for EF-hand domain in binding and inactivation

2019 ◽  
Vol 116 (22) ◽  
pp. 10763-10772 ◽  
Author(s):  
Bernd R. Gardill ◽  
Ricardo E. Rivera-Acevedo ◽  
Ching-Chieh Tung ◽  
Filip Van Petegem
Keyword(s):  
Crystal Structure ◽  
Binding Sites ◽  
Binding Mode ◽  
Conformational Switch ◽  
Channel Inactivation ◽  
Dependent Inactivation ◽  
Ef Hand ◽  
Inherited Arrhythmia ◽  
A Site

Voltage-gated sodium (NaV) and calcium channels (CaV) form targets for calmodulin (CaM), which affects channel inactivation properties. A major interaction site for CaM resides in the C-terminal (CT) region, consisting of an IQ domain downstream of an EF-hand domain. We present a crystal structure of fully Ca2+-occupied CaM, bound to the CT of NaV1.5. The structure shows that the C-terminal lobe binds to a site ∼90° rotated relative to a previous site reported for an apoCaM complex with the NaV1.5 CT and for ternary complexes containing fibroblast growth factor homologous factors (FHF). We show that the binding of FHFs forces the EF-hand domain in a conformation that does not allow binding of the Ca2+-occupied C-lobe of CaM. These observations highlight the central role of the EF-hand domain in modulating the binding mode of CaM. The binding sites for Ca2+-free and Ca2+-occupied CaM contain targets for mutations linked to long-QT syndrome, a type of inherited arrhythmia. The related NaV1.4 channel has been shown to undergo Ca2+-dependent inactivation (CDI) akin to CaVs. We present a crystal structure of Ca2+/CaM bound to the NaV1.4 IQ domain, which shows a binding mode that would clash with the EF-hand domain. We postulate the relative reorientation of the EF-hand domain and the IQ domain as a possible conformational switch that underlies CDI.

scholarly journals Crystal Structure of the Streptomyces coelicolor Sortase E1 Transpeptidase Provides Insight into the Binding Mode of the Novel Class E Sorting Signal

PLoS ONE ◽  
2016 ◽  
Vol 11 (12) ◽  
pp. e0167763 ◽  
Author(s):  
Michele D. Kattke ◽  
Albert H. Chan ◽  
Andrew Duong ◽  
Danielle L. Sexton ◽  
Michael R. Sawaya ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Streptomyces Coelicolor ◽  
Binding Mode ◽  
The Novel ◽  
Sorting Signal ◽  
Insight Into ◽  
Class E

scholarly journals Mechanism of action and NAD+-binding mode revealed by the crystal structure of L-histidinol dehydrogenase

2002 ◽  
Vol 99 (4) ◽  
pp. 1859-1864 ◽  
Author(s):  
J. A. R. G. Barbosa ◽  
J. Sivaraman ◽  
Y. Li ◽  
R. Larocque ◽  
A. Matte ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Mechanism Of Action ◽  
Binding Mode ◽  
Histidinol Dehydrogenase

scholarly journals Cyclic Boronates Inhibit All Classes of β-Lactamases

2017 ◽  
Vol 61 (4) ◽  
Author(s):  
Samuel T. Cahill ◽  
Ricky Cain ◽  
David Y. Wang ◽  
Christopher T. Lohans ◽  
David W. Wareham ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Bacterial Infections ◽  
Binding Mode ◽  
Gram Negative ◽  
Content Type ◽  
Class A ◽  
Class D ◽  
Dual Action ◽  
The Common ◽  
Continued Use

ABSTRACT β-Lactamase-mediated resistance is a growing threat to the continued use of β-lactam antibiotics. The use of the β-lactam-based serine-β-lactamase (SBL) inhibitors clavulanic acid, sulbactam, and tazobactam and, more recently, the non-β-lactam inhibitor avibactam has extended the utility of β-lactams against bacterial infections demonstrating resistance via these enzymes. These molecules are, however, ineffective against the metallo-β-lactamases (MBLs), which catalyze their hydrolysis. To date, there are no clinically available metallo-β-lactamase inhibitors. Coproduction of MBLs and SBLs in resistant infections is thus of major clinical concern. The development of “dual-action” inhibitors, targeting both SBLs and MBLs, is of interest, but this is considered difficult to achieve due to the structural and mechanistic differences between the two enzyme classes. We recently reported evidence that cyclic boronates can inhibit both serine- and metallo-β-lactamases. Here we report that cyclic boronates are able to inhibit all four classes of β-lactamase, including the class A extended spectrum β-lactamase CTX-M-15, the class C enzyme AmpC from Pseudomonas aeruginosa, and class D OXA enzymes with carbapenem-hydrolyzing capabilities. We demonstrate that cyclic boronates can potentiate the use of β-lactams against Gram-negative clinical isolates expressing a variety of β-lactamases. Comparison of a crystal structure of a CTX-M-15:cyclic boronate complex with structures of cyclic boronates complexed with other β-lactamases reveals remarkable conservation of the small-molecule binding mode, supporting our proposal that these molecules work by mimicking the common tetrahedral anionic intermediate present in both serine- and metallo-β-lactamase catalysis.

scholarly journals Truly Target-Focused Pharmacophore Modeling: A Novel Tool for Mapping Intermolecular Surfaces

Molecules ◽  
2018 ◽  
Vol 23 (8) ◽  
pp. 1959 ◽  
Author(s):  
Jérémie Mortier ◽  
Pratik Dhakal ◽  
Andrea Volkamer
Keyword(s):  
Protein Interactions ◽  
Pharmacophore Modeling ◽  
Macromolecular Structure ◽  
Target Structure ◽  
Protein Protein Interactions ◽  
Energy Functions ◽  
Chemical Structures ◽  
Molecular Interaction Fields ◽  
Protein Classes ◽  
Pharmacophore Models

Pharmacophore models are an accurate and minimal tridimensional abstraction of intermolecular interactions between chemical structures, usually derived from a group of molecules or from a ligand-target complex. Only a limited amount of solutions exists to model comprehensive pharmacophores using the information of a particular target structure without knowledge of any binding ligand. In this work, an automated and customable tool for truly target-focused (T²F) pharmacophore modeling is introduced. Key molecular interaction fields of a macromolecular structure are calculated using the AutoGRID energy functions. The most relevant points are selected by a newly developed filtering cascade and clustered to pharmacophore features with a density-based algorithm. Using five different protein classes, the ability of this method to identify essential pharmacophore features was compared to structure-based pharmacophores derived from ligand-target interactions. This method represents an extremely valuable instrument for drug design in a situation of scarce ligand information available, but also in the case of underexplored therapeutic targets, as well as to investigate protein allosteric pockets and protein-protein interactions.

scholarly journals Crystal structure reveals a unique ABIN-Ubs binding mode

2019 ◽  
Vol 75 (a1) ◽  
pp. a22-a22
Author(s):  
Jhen-Yi Hong ◽  
Su-Chang Lin ◽  
Yu-Chih Lo
Keyword(s):  
Crystal Structure ◽  
Binding Mode
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