A comparative study of fragment screening methods on the p38�� kinase: new methods, new insights

The stress-activated kinase p38α was used to evaluate a fragment-based drug discovery approach using the BioFocus fragment library. Compounds were screened by surface plasmon resonance (SPR) on a Biacore(?) T100 against p38α and two selectivity targets. A sub-set of our library was the focus of detailed follow-up analyses that included hit confirmation, affinity determination on 24 confirmed, selective hits and competition assays of these hits with respect to a known ATP binding site inhibitor. In addition, functional activity against p38α was assessed in a biochemical assay using a mobility shift platform (LC3000, Caliper LifeSciences). A selection of fragments was also evaluated using fluorescence lifetime (FLEXYTE(?)) and microscale thermophoresis (Nanotemper) technologies. A good correlation between the data for the different assays was found. Crystal structures were solved for four of the small molecules complexed to p38α. Interestingly, as determined both by X-ray analysis and SPR competition experiments, three of the complexes involved the fragment at the ATP binding site, while the fourth compound bound in a distal site that may offer potential as a novel drug target site. A first round of optimization around the remotely bound fragment has led to the identification of a series of triazole-containing compounds. This approach could form the basis for developing novel and active p38α inhibitors. More broadly, it illustrates the power of combining a range of biophysical and biochemical techniques to the discovery of fragments that facilitate the development of novel modulators of kinase and other drug targets.     

Solid-phase extraction and high-performance liquid chromatography mass spectrometry analysis of nitrosamines in treated drinking water and wastewater

N-Nitrosamines, including N-nitrosodimethylamine (NDMA), were identified as chlorination byproducts in drinking water in 1989. Nitrosamines are known rodent carcinogens and probable human carcinogens, and so they are considered disinfection byproducts (DBPs) of public health concern. Epidemiological studies show a potential association of consumption of chlorinated drinking water with an increased risk of bladder cancer. As small, relatively polar DBPs that often occur at low-ng/L concentrations in water, nitrosamines pose analytical challenges for accurate determination. Sample preparation (e.g., the commonly used solid-phase extraction) plays a critical role in achieving reliable determination of nitrosamines at ng/L concentrations. Historically, gas chromatography (GC)-based techniques have been used for nitrosamine analysis. Recently, newly developed liquid chromatography–tandem mass spectrometry (LC-MS²) methods have shown potential advantages in determining polar DBPs. This review focuses on the sample preconcentration methods and LC-MS² determination of nitrosamines in drinking water and wastewater. It also provides a historical perspective on nitrosamines and their occurrence in drinking water.     

Modelling the infrared ManPAD Track Angle Bias missile countermeasure

The paper describes the concept of missile evolution and the development of a range of missile advancements designed to defeat the evolving array of aircraft defensive measures. The paper describes a typical military aircraft infrared signature and looks at how examination of different spectral parts of the target signature can be used to determine if an aircraft has deployed flare countermeasures. This information can then be used to trigger a missile countermeasure in attempt for the missile to continue with a successful engagement. The paper examines the Track Angle Bias missile countermeasure and details the results of over 1000 engagement simulations designed to test the effectiveness of the missile countermeasure. The paper references the work published in IRPT Volume 53, Issue 5, September 2010, Pages 372–380.     

Modelling an infrared Man Portable Air Defence System

The global proliferation of shoulder launched IR Man Portable Air Defence Systems (ManPADS) has resulted in the existence of a serious threat to both civilian and military aircraft from terrorist attack. Some of the older generations of ManPADS can be defeated with modern countermeasures but even the most sophisticated protection still has vulnerabilities to the latest family of ManPADS. This paper describes the work undertaken by the authors to model a second generation ManPAD, based on the Russian SA-14, and assess the vulnerabilities of aircraft both with and without flare countermeasures from these systems. The conclusions are the results of over 11,000 simulated firings against targets of varying aspects, velocities and altitudes.     

Functional effects of spinocerebellar ataxia type 13 mutations are conserved in zebrafish Kv3.3 channels

Background  

The zebrafish has been suggested as a model system for studying human diseases that affect nervous system function and motor output. However, few of the ion channels that control neuronal activity in zebrafish have been characterized. Here, we have identified zebrafish orthologs of voltage-dependent Kv3 (KCNC) K⁺ channels. Kv3 channels have specialized gating properties that facilitate high-frequency, repetitive firing in fast-spiking neurons. Mutations in human Kv3.3 cause spinocerebellar ataxia type 13 (SCA13), an autosomal dominant genetic disease that exists in distinct neurodevelopmental and neurodegenerative forms. To assess the potential usefulness of the zebrafish as a model system for SCA13, we have characterized the functional properties of zebrafish Kv3.3 channels with and without mutations analogous to those that cause SCA13.     

ChemInform Abstract: Gas‐Phase Molecular Structures of Third Row Transition‐Metal Hexafluorides WF6, ReF6, OsF6, IrF6, and PtF6. An Electron‐Diffraction and ab initio Study.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.     

Modular Metal-Quinone Networks with Tunable Architecture and Functionality

Nanostructured materials with tunable structures and functionality are of interest in diverse areas. Herein, metal ions are coordinated with quinones through metal-acetylacetone coordination bonds to generate a class of structurally tunable, universally adhesive, hydrophilic, and pH-degradable materials. A library of metal-quinone networks (MQNs) is produced from five model quinone ligands paired with nine metal ions, leading to the assembly of particles, tubes, capsules, and films. Importantly, MQNs show bidirectional pH-responsive disassembly in acidic and alkaline solutions, where the quinone ligands mediate the disassembly kinetics, enabling temporal and spatial control over the release of multiple components using multilayered MQNs. Leveraging this tunable release and the inherent medicinal properties of quinones, MQN prodrugs with a high drug loading (>89 wt %) are engineered using doxorubicin for anti-cancer therapy and shikonin for the inhibition of the main protease in the SARS-CoV-2 virus.     

ChemInform Abstract: Molecular Structure of the Aluminum Halides,Al2Cl6, AlCl3, Al2Br6, AlBr3, and AlI3, Obtained by Gas-Phase Electron Diffraction and ab initio Molecular Orbital Calculations.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.     

Correspondence on “Crystalline Porous Organic Salt for Ultrarapid Adsorption/Desorption-Based Atmospheric Water Harvesting by Dual Hydrogen Bond System”

In a recent Research Article, Ben and co-workers reported a hydrogen-bonded framework prepared from a 4⁺ tetra-amidinium component and a 4⁻ tetra-sulfonate component, termed CPOS-6. They showed that CPOS-6 could reversibly adsorb and desorb water over a narrow humidity window, and that this material offered potential for applications in atmospheric water harvesting. This conclusion was supported by experiments that showed the material was stable over 50 adsorption/desorption cycles and that the kinetics of these cycles were very rapid. In this Correspondence we present additional structural data regarding this framework in both its hydrated and dehydrated states and thus discern the mechanism of water binding. These data do not disagree with Ben and co-workers’ findings: rather they emphasise how remarkable the cyclability and rapid kinetics of adsorption/desorption are, as these processes involve a complete crystal-to-crystal rearrangement of the framework.