Free-flow isoelectric focusing of proteins remaining in cell fragments following sonication of thyroid carcinoma cells

The method of preparing protein mixtures for electrophoretic analysis of membrane-associated cell proteins was improved. By sonication, about one-half of the proteins of thyroid cells were released into the supernatant, while the other half preferentially comprising membrane proteins still remained in cell fragments, which could be sedimented by centrifugation. After sonication, even those proteins which remained in cell fragments, could completely be dissolved by free-flow isoelectric focusing media. They migrated through the free-flow electrophoresis chamber without forming precipitates. Because of these improvements, it was possible to show that the two thyroid cancer cell lines ML-1 and ONCO-DG1 express cytokeratin 8 at similar rates, but cytokeratins 7 and 18 differently. In addition, the presence of inorganic pyrophosphatase, tubulin-beta-5, and tubulin-beta-1 chains in human thyroid cells was proved for the first time.     

Aluminum alkoxy-catalyzed biomass conversion of glucose to 5-hydroxymethylfurfural: Mechanistic study of the cooperative bifunctional catalysis

Density functional theory calculations were performed to understand the detailed reaction mechanism of aluminum alkoxy-catalyzed conversion of glucose to 5-hydroxymethylfurfural (HMF) using Al(OMe)₃ as catalyst. Potential energy surfaces were studied for aggregates formed between the organic compounds and Al(OMe)₃ and effects of the medium were considered via continuum solvent models. The reaction takes place via two stages: isomerization from glucose to fructose (stage I) and transformation of fructose to HMF (stage II). Stage II includes three successive dehydrations, which begins with a 1,2-elimination to form an enolate (i.e., B), continues with the formation of the acrolein moiety (i.e., D), and ends with the formation of the furan ring (i.e., HMF). All of these steps are facilitated by aluminum alkoxy catalysis. The highest barriers for stage I and stage II are 23.9 and 31.2 kcal/mol, respectively, and the overall catalytic reaction is highly exothermic. The energetic and geometric results indicate that the catalyzed reaction path has feasible kinetics and thermodynamics and is consistent with the experimental process under high temperature (i.e., 120 °C). Remarkably, the released water molecules in stage II act as the product, reactant, proton shuttle, as well as stabilizer in the conversion of fructose to HMF. The metal–ligand functionality of the Al(OMe)₃ catalyst, which combines cooperative Lewis acid and Lewis base properties and thereby enables proton shuttling, plays a crucial role in the overall catalysis and is responsible for the high reactivity. © 2019 Wiley Periodicals, Inc.     

A Structural View on Medicinal Chemistry Strategies against Drug Resistance

The natural phenomenon of drug resistance is a widespread issue that hampers the performance of drugs in many major clinical indications. Antibacterial and antifungal drugs are affected, as well as compounds for the treatment of cancer, viral infections, or parasitic diseases. Despite the very diverse set of biological targets and organisms involved in the development of drug resistance, the underlying molecular mechanisms have been identified to understand the emergence of resistance and to overcome this detrimental process. Detailed structural information on the root causes for drug resistance is nowadays frequently available, so next‐generation drugs can be designed that are anticipated to suffer less from resistance. This knowledge‐based approach is essential for fighting the inevitable occurrence of drug resistance.     

SrIrIn6 – An Intergrowth of SrIrIn4 with Indium Slabs

The indium-rich intermetallic compound SrIrIn₆ was synthesized from the elements in a sealed tantalum ampoule at 1173 K, followed by slow cooling for crystal growth. SrIrIn₆ crystallizes with a new structure type which was characterized by X-ray powder and single crystal diffraction: Pmma, a = 852.34(2), b = 434.54(5), c = 1059.18(6) pm, wR₂ = 0.0178, 884 F² values, and 32 variables. The SrIrIn₆ structure shows two basic building units: (i) Ir@In₉ tricapped trigonal prisms (261–292 pm Ir–In) and (ii) distorted bcc In@In₈ cubes (301 to 329 pm In–In). The strontium cations fill cages within the complex three-dimensional [IrIn₆] network and have coordination number 13 (Sr@In₁₃) in form of a tricapped pentagonal prism. The SrIrIn₆ structure can be described as a simple intergrowth variant of SrIrIn₄ (LaCoAl₄ type) with indium slabs. The crystal chemical similarities with the structures of SrIrIn₄, SrIr₂In₈ and Eu₃Ir₂In₁₅ are discussed.     

On the equilibrium structures of the complexes H2C3H+ · Ar and c-C3H3(+) · Ar: results of explicitly correlated coupled cluster calculations

Explicitly correlated coupled cluster theory at the CCSD(T)-F12x (x = a, b) level [T. B. Adler et al., J. Chem. Phys. 127, 221106 (2007)] has been employed in a study of the potential energy surfaces for the complexes H(2)C(3)H(+) · Ar and c-C(3)H(3)(+) · Ar. For the former complex, a pronounced minimum with C(s) symmetry was found (D(e) ≈ 780 cm(-1)), well below the local "H-bound" minimum with C(2v) symmetry (D(e) ≈ 585 cm(-1)). The absorption at 3238 cm(-1) found in the recent infrared photodissociation spectra [A. M. Ricks et al., J. Chem. Phys. 132, 051101 (2010)] is, thus, interpreted as an essentially free acetylenic CH stretching vibration of the propargyl cation. A global minimum of C(s) symmetry was also obtained for c-C(3)H(3)(+) (D(e) ≈ 580 cm(-1)), but the energy difference with respect to the local C(2v) minimum is only 54 cm(-1).     

Beobachtung von Koagulationserscheinungen in der Strömungsdoppelbrechungstrommel von Signer

Zusammenfassung Bei übersättigten Lösungen, die ihre Eigenschaften in ruhendem Zustande nur sehr langsam verändern, kann in der Strömungsapparatur durch die laminare Bewegung ein rasches Wachstum der gelösten Teilchen einsetzen, das durch die Messung der Strömungsdoppelbrechung fortlaufend verfolgbar ist. Nach dem Meßverfahren von Signer können der Auslöschwinkel und die Stärke der Doppelbrechung aus der Kompensationskurve, die eine Sinusschwingung vorstellt, abgelesen werden. Durch fortlaufende Registrierung dieser Kurve können Veränderungen des Auslöschwinkels, der Auskunft über das Längen-Breitenverhältnis der Teilchen gibt, und die Stärke der Doppelbrechung, die von der Teilchenorientierung und bei konstantem Längen-Breitenverhältnis außerdem von der Teilchendicke abhängt, nachgewiesen werden.Bei den untersuchten Lösungen von Karnaubawachs und Kongorot zeigen die geströmten Teilchen ein deutliches Wachstum, das nach den Beobachtungsdaten nicht zu stäbigen, sondern eher zu flächigen bis massigen Sekundärteilchen führt.     

Die Bestimmung der Verseifungszahl in Fetten und ?len

Ohne Zusammenfassung     

Ersatz der Podbielniak-Destillation durch eine Kombination von Graschromatographie und Gravimetrie

Zusammenfassung An Stelle der Podbielniak-Analyse für Gasproben, die neben Inertgasen und leichten Kohlenwasserstoffen auch C₅- und höhere Kohlenwasserstoffe enthalten, wird ein neues Verfahren vorgeschlagen. Die Inertgase und leichten Kohlenwasserstoffe werden wie üblich gaschromatographisch bestimmt. Zusätzlich trennt man aus einer zweiten Probe gaschromatographisch die leichten Anteile ab, spült durch Umkehr der Trägergasrichtung die Summe der schweren Kohlenwasserstoffe wieder aus der Säule und bestimmt ihre Menge durch Wägung.     

Synthese d'lsosélénazoles et de benzisosélénazoles-1,2

A general preparation of the isoselenazole ring by addition of bromine followed by ammonia on cis-β–methylseleno-2-propenal is described. This reaction was successfully applied to 1,2-benz-isoselenazole, a new heterocyclic system.