SciCombinator

Discover the most talked about and latest scientific content & concepts.

Journal: Angewandte Chemie (International ed. in English)

226

During the beer brewing process, bitter tasting cis and trans iso-α-acids are generated from the precursor α-acids found in hops. The absolute configurations of the α-acid (-)-humulone and several of its derivatives have now been elucidated by X-ray crystallography, thus resolving decades of confusion over the humulone isomerization mechanism.

Concepts: X-ray, X-ray crystallography, Brewing, Beer, Hops, Brewery

136

Exon 20 insertion (Ex20Ins) mutations are the third most prevalent epidermal growth factor receptor (EGFR) activating mutation and the most prevalent HER2 mutation in non-small cell lung cancer (NSCLC). Novel therapeutics for the patients with Ex20Ins mutations are urgently needed, due to their poor responses to the currently approved EGFR and HER2 inhibitors. Here we report the discovery of highly potent and broadly effective EGFR and HER2 Ex20Ins mutant inhibitors. The co-crystal structure of compound 1b in complex with wild type EGFR clearly revealed an additional hydrophobic interaction of 4-fluorobenzene ring within a deep hydrophobic pocket, which has not been widely exploited in the development of EGFR and HER2 inhibitors. As compared with afatinib, compound 1a exhibited superior inhibition of proliferation and signaling pathways in Ba/F3 cells harboring either EGFR or HER2 Ex20Ins mutations, and in the EGFR P772_H773insPNP patient-derived lung cancer cell line DFCI127. Our study identifies promising strategies for development of EGFR and HER2 Ex20Ins mutant inhibitors.

52

Strongly luminescent iridium(III) complexes, [Ir(C,N)2 (S,S)](+) (1) and [Ir(C,N)2 (O,O)] (2), containing C,N (phenylquinoline), O,O (diketonate), or S,S (dithione) chelating ligands, have been characterized by X-ray crystallography and DFT calculations. Their long phosphorescence lifetimes in living cancer cells give rise to high quantum yields for the generation of (1) O2 , with large 2-photon absorption cross-sections. 2 is nontoxic to cells, but potently cytotoxic to cancer cells upon brief irradiation with low doses of visible light, and potent at sub-micromolar doses towards 3D multicellular tumor spheroids with 2-photon red light. Photoactivation causes oxidative damage to specific histidine residues in the key proteins in aldose reductase and heat-shock protein-70 within living cancer cells. The oxidative stress induced by iridium photosensitizers during photoactivation can increase the levels of enzymes involved in the glycolytic pathway.

Concepts: DNA, Protein, Cell, Cancer, Adenosine triphosphate, X-ray, Glucose, Oxidative phosphorylation

43

Precise spatiotemporal control of physiological processes by optogenetic devices inspired by synthetic biology may provide novel treatment opportunities for gene- and cell-based therapies. An erectile optogenetic stimulator (EROS), a synthetic designer guanylate cyclase producing a blue-light-inducible surge of the second messenger cyclic guanosine monophosphate (cGMP) in mammalian cells, enabled blue-light-dependent penile erection associated with occasional ejaculation after illumination of EROS-transfected corpus cavernosum in male rats. Photostimulated short-circuiting of complex psychological, neural, vascular, and endocrine factors to stimulate penile erection in the absence of sexual arousal may foster novel advances in the treatment of erectile dysfunction.

Concepts: Sexual intercourse, Andrology, Erectile dysfunction, Ejaculation, Penis, Cyclic guanosine monophosphate, Erection, Sexual arousal

31

Electricity generation from flowing water has been developed for over a century and plays a critical role in our lives. Generally, heavy and complex facilities are required for electricity generation, while utilizing these technologies for applications that require a small size and high flexibility is difficult. Here, we developed a fluidic nanogenerator fiber from an aligned carbon nanotube sheet to generate electricity from any flowing water source in the environment as well as in the human body. The power conversion efficiency reached 23.3%. The fluidic nanogenerator fiber was flexible and stretchable, and the high performance was well maintained after deformation over 1,000,000 cycles. The fiber also offered unique and promising advantages, such as the ability to be woven into fabrics for large-scale applications.

Concepts: Human, Natural environment, Carbon, United Kingdom, Human body, Carbon nanotube, Tensile strength, Power

31

Silicon analogues of the most prominent carbon nanostructures, namely, hollow spheroidals such as C60 and the fullerene family, have been unknown to date. Herein we show that discrete Si20 dodecahedra, stabilized by an endohedral guest and valence saturation, are accessible in preparative yields through a chloride-induced disproportionation reaction of hexachlorodisilane in the presence of tri(n-butyl)amine. X-ray crystallography revealed that each silicon dodecahedron contains an endohedral chloride ion that imparts a net negative charge. Eight chloro substituents and twelve trichlorosilyl groups are attached to the surface of each cluster in a strictly regioregular arrangement, a thermodynamically preferred substitution pattern according to quantum-chemical assessment. Our results demonstrate that the wet-chemical self-assembly of a complex, monodisperse Si nanostructure is possible under mild conditions starting from simple Si2 building blocks.

Concepts: Electron, Electric charge, Carbon, Sodium chloride, Ion, X-ray crystallography, Chlorine, Chloride

30

Messenger RNA (mRNA) represents a promising class of nucleic acid drugs. Although numerous carriers have been developed for mRNA delivery, the inefficient mRNA expression inside cells remains a major challenge. Inspired by the dependence of mRNA on 3'-terminal polyadenosine nucleotides (poly A) and poly A binding proteins (PABPs) for optimal expression, we complexed synthetic mRNA containing a poly A tail with PABPs in a stoichiometric manner and stabilized the ribonucleoproteins (RNPs) with a family of polypeptides bearing different arrangements of cationic side groups. We found that the molecular structure of these polypeptides modulates the degree of PABP-mediated enhancement of mRNA expression. This strategy elicits an up to 20-fold increase in mRNA expression in vitro and an approximately fourfold increase in mice. These findings suggest a set of new design principles for gene delivery by the synergistic co-assembly of mRNA with helper proteins.

Concepts: DNA, Protein, Cell nucleus, Gene expression, Transcription, RNA, Messenger RNA, Polyadenylation

30

To turn waste into treasure and meet the urgent requirement of developing high performance cathode for potassium ion batteries, as a proof-of concept experiment, we first propose and demonstrate a new strategy to fabricate the flexible binder-free potassium-ion batteries (KIBs) electrode via in situ transforming the corrosion layer of rusty stainless steels mesh (SSM) into compact stack layer of PB nanocubes (PB@SSM). Unexpectedly, when further coated with reduced graphite oxide (RGO) to enhance electric conductivity and structural stability, the obtained stable, low-cost, and binder-free RGO@PB@SSM cathode exhibits excellent electrochemical performances for KIBs, including high capacity (96 mAh g-1), high discharge voltage (3.3 V) and superior rate capability (1000 mAh g-1) as well as outstanding cycle stability (305 cycles). The obtained results open new avenue for both the recycle of rust stainless steels and developing of novel cathode for KIBs.

Concepts: Electrochemistry, Battery, Electrolyte, Electrolysis, Steel, Passivation, Corrosion, Rust

30

Following his seminal work in 1953, Stanley Miller conducted an experiment in 1958 to study the polymerization of amino acids under simulated early Earth conditions. In the experiment, Miller sparked a gas mixture of CH4 , NH3 , and H2 O, while intermittently adding the plausible prebiotic condensing reagent cyanamide. For unknown reasons, an analysis of the samples was not reported. We analyzed the archived samples for amino acids, dipeptides, and diketopiperazines by liquid chromatography, ion mobility spectrometry, and mass spectrometry. A dozen amino acids, 10 glycine-containing dipeptides, and 3 glycine-containing diketopiperazines were detected. Miller’s experiment was repeated and similar polymerization products were observed. Aqueous heating experiments indicate that Strecker synthesis intermediates play a key role in facilitating polymerization. These results highlight the potential importance of condensing reagents in generating diversity within the prebiotic chemical inventory.

Concepts: Protein, Amino acid, Acid, Amine, Ammonia, Mass spectrometry, Hydrogen, Chemistry

29

Easy peasy: The title reaction employs N-formylsaccharin, which is an easily accessible crystalline compound, as an effective CO source. The reactions proceed with a small excess of the CO source at moderate temperatures and were successfully applied to a wide range of aryl bromides. DMF=N,N-dimethylformamide, dppb=1,4-bis-(diphenylphosphino)butane.

Concepts: Chemical reaction