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Identification and Visualization of Kinase-Specific Subpockets. - Journal of chemical information and modeling
The identification and design of selective compounds is important for the reduction of unwanted side effects as well as for the development of tool compounds for target validation studies. This is in particular true for therapeutically important protein families that possess conserved folds and have numerous members such as kinases. To support the design of selective kinase inhibitors, we developed a novel approach that allows to identify specificity determining subpockets between closely related kinases solely based on their three-dimensional structures. To account for the intrinsic flexibility of the proteins, multiple X-ray structures of the target protein of interest as well as of unwanted off-target(s) are taken into account. The binding pockets of these protein structures are calculated and fused to a combined target and off-target pocket, respectively. Subsequently, shape differences between these two combined pockets are identified via fusion rules. The approach provides a user-friendly visualization of target-specific areas in a binding pocket which should be explored when designing selective compounds. Furthermore, the approach can be easily combined with in silico alanine mutation studies to identify selectivity determining residues. The potential impact of the approach is demonstrated in four retrospective experiments on closely related kinases, i.e. p38Î± vs. Erk2, PAK1 vs. PAK4, ITK vs. AurA, and BRAF vs. VEGFR2. Overall, the presented approach does not require any profiling data for training purposes, provides an intuitive visualization of a large number of protein structures at once, and could also be applied to other target classes.
Design, synthesis, antimicrobial evaluation and molecular docking studies of some new 2,3-dihydrothiazoles and 4-thiazolidinones containing sulfisoxazole. - Journal of enzyme inhibition and medicinal chemistry
Microbial resistance to the available drugs poses a serious threat in modern medicine. We report the design, synthesis and in vitro antimicrobial evaluation of new functionalized 2,3-dihydrothiazoles and 4-thiazolidinones tagged with sulfisoxazole moiety. Compound 8d was most active against Bacillis subtilis (MIC, 0.007â€‰Âµg/mL). Moreover, compounds 7c-d and 8c displayed significant activities against B. subtilis and Streptococcus pneumoniae (MIC, 0.03-0.06â€‰Âµg/mL and 0.06-0.12â€‰Âµg/mL versus ampicillin 0.24â€‰Âµg/mL and 0.12â€‰Âµg/mL; respectively). Compounds 7a and 7c-d were highly potent against Escherichia coli (MIC, 0.49-0.98â€‰Âµg/mL versus gentamycin 1.95â€‰Âµg/mL). On the other hand, compounds 7e and 9c were fourfolds more active than amphotericin B against Syncephalastrum racemosum. Molecular docking studies showed that the synthesized compounds could act as inhibitors for the dihydropteroate synthase enzyme (DHPS). This study is a platform for the future design of more potent antimicrobial agents.
Pocketome of human kinases: prioritizing the ATP binding sites of (yet) untapped protein kinases for drug discovery. - Journal of chemical information and modeling
Protein kinases are involved in a variety of diseases including cancer, inflammation, and autoimmune disorders. Although the development of new kinase inhibitors is a major focus in pharmaceutical research, a large number of kinases remained so far unexplored in drug discovery projects. The selection and assessment of targets is an essential but challenging area. Today, a few thousands of experimentally determined kinase structures are available, covering about half of the human kinome. This large structural source allows guiding the target selection via structure-based druggability prediction approaches such as DoGSiteScorer. Here, a thorough analysis of the ATP pockets of the entire human kinome in the DFG-in state is presented in order to prioritize novel kinase structures for drug discovery projects. For this, all human kinase X-ray structures available in the PDB were collected, and homology models were generated for the missing part of the kinome. DoGSiteScorer was used to calculate geometrical and physicochemical properties of the ATP pockets and to predict the potential of each kinase to be druggable. The results indicate that about 75% of the kinome are in principle druggable. Top ranking structures comprise kinases that are primary targets of known approved drugs but additionally point to so far less explored kinases. The presented analysis provides new insights into the druggability of ATP binding pockets of the entire kinome. We anticipate this comprehensive druggability assessment of protein kinases to be helpful for the community to prioritize so far untapped kinases for drug discovery efforts.
Exploring the free-energy landscape of carbohydrate-protein complexes: development and validation of scoring functions considering the binding-site topology. - Journal of computer-aided molecular design
Carbohydrates play a key role in a variety of physiological and pathological processes and, hence, represent a rich source for the development of novel therapeutic agents. Being able to predict binding mode and binding affinity is an essential, yet lacking, aspect of the structure-based design of carbohydrate-based ligands. We assembled a diverse data set comprising 273 carbohydrate-protein crystal structures with known binding affinity and evaluated the prediction accuracy of a large collection of well-established scoring and free-energy functions, as well as combinations thereof. Unfortunately, the tested functions were not capable of reproducing binding affinities in the studied complexes. To simplify the complex free-energy surface of carbohydrate-protein systems, we classified the studied proteins according to the topology and solvent exposure of the carbohydrate-binding site into five distinct categories. A free-energy model based on the proposed classification scheme reproduced binding affinities in the carbohydrate data set with an r(2) of 0.71 and root-mean-squared-error of 1.25 kcal/mol (N = 236). The improvement in model performance underlines the significance of the differences in the local micro-environments of carbohydrate-binding sites and demonstrates the usefulness of calibrating free-energy functions individually according to binding-site topology and solvent exposure.
Design, synthesis, antimicrobial evaluation and molecular docking studies of some new thiophene, pyrazole and pyridone derivatives bearing sulfisoxazole moiety. - European journal of medicinal chemistry
Development of new antimicrobial agents is a good solution to overcome drug-resistance problems. In this context, new functionalized thiophene, acrylamide, arylhydrazone, pyrazole and pyridone derivatives bearing sulfisoxazole moiety were designed, synthesized and evaluated for their in vitro antibacterial and antifungal activities. Among the synthesized compounds, thiophene 4d and 6-thioglucosylpyridone 17 displayed significant antibacterial activities against Escherichia coli (MIC, 0.007 Î¼g/mL vs gentamycin 1.95 Î¼g/mL) and Bacillis subtilis (MIC, 0.007 Î¼g/mL vs ampicillin 0.24 Î¼g/mL), respectively. Whereas, the pyrazole 6 showed the highest antifungal activity against Aspergillus fumigates (MIC, 0.03 Î¼g/mL vs amphotericin B 0.12 Î¼g/mL). In general, most of the synthesized compounds exhibited better antimicrobial activities than sulfisoxazole; this might be attributed to the synergistic effect of the sulfonamide and attached heterocyclic moieties as well as the increased lipophilic characters of the synthesized compounds. Molecular docking studies indicated that the synthesized compounds could occupy both p-amino benzoic acid (PABA) and pterin binding pockets of the dihydropteroate synthase (DHPS), suggesting that the target compounds could act by the inhibition of microbial DHPS enzyme. The results provide important information for the future design of more potent antimicrobial agents.Copyright Â© 2014 Elsevier Masson SAS. All rights reserved.
Molecular design and synthesis of HCV inhibitors based on thiazolone scaffold. - European journal of medicinal chemistry
A series of thiazolone derivatives was designed and synthesized as potential HCV NS5B allosteric polymerase inhibitors at the allosteric site thumb II. Their antiviral activity was evaluated and molecular modeling was utilized to give further envision on their probable binding modes in the allosteric binding site. Among the tested molecules, compound 9b displayed sub-micromolar inhibitory activity with an EC50 of 0.79 Î¼M indicating excellent potency profile. It also showed good safety profile (CC50â‰¥75 Î¼M and SIâ‰¥94.3).Copyright Â© 2013 Elsevier Masson SAS. All rights reserved.
Analogs design, synthesis and biological evaluation of peptidomimetics with potential anti-HCV activity. - Bioorganic & medicinal chemistry
Two series of peptidomimetics were designed, prepared and evaluated for their anti-HCV activity. One series possesses a C-terminal carboxylate functionality. In the other series, the electrophilic vinyl sulfonate moiety was introduced as a novel class of HCV NS3/4A protease inhibitors. In vitro based studies were then performed to evaluate the efficacies of the inhibitors using Human hepatoma cells, with the vinyl sulfonate ester (10) in particular, found to have highly potent anti-HCV activity with an EC(50) = 0.296 Î¼M. Finally, molecular modeling studies were performed through docking of the synthesized compounds in the HCV NS3/4A protease active site to assess their binding modes with the enzyme and gain further insight into their structure-activity relationships.Copyright Â© 2013 Elsevier Ltd. All rights reserved.
A molecular-modeling toolbox aimed at bridging the gap between medicinal chemistry and computational sciences. - International journal of molecular sciences
In the current era of high-throughput drug discovery and development, molecular modeling has become an indispensable tool for identifying, optimizing and prioritizing small-molecule drug candidates. The required background in computational chemistry and the knowledge of how to handle the complex underlying protocols, however, might keep medicinal chemists from routinely using in silico technologies. Our objective is to encourage those researchers to exploit existing modeling technologies more frequently through easy-to-use graphical user interfaces. In this account, we present two innovative tools (which we are prepared to share with academic institutions) facilitating computational tasks commonly utilized in drug discovery and development: (1) the VirtualDesignLab estimates the binding affinity of small molecules by simulating and quantifying their binding to the three-dimensional structure of a target protein; and (2) the MD Client launches molecular dynamics simulations aimed at exploring the time-dependent stability of ligand-protein complexes and provides residue-based interaction energies. This allows medicinal chemists to identify sites of potential improvement in their candidate molecule. As a case study, we present the application of our tools towards the design of novel antagonists for the FimH adhesin.
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3525 S Martin Luther King Jr Blvd Lansing, MI 48910
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