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61.
Olga Bienemann Ann‐Kathrin Froin Ines dos Santos Vieira Ramona Wortmann Alexander Hoffmann Prof. Dr. Sonja Herres‐Pawlis 《无机化学与普通化学杂志》2012,638(11):1683-1690
This contribution reports the synthesis of the novel tetradentate bisguanidine ligand 2′,2′‐[ethane‐1, 2‐diylbis(methylazanediyl)]bis(ethane‐2, 1‐diyl)bis(1, 1, 3, 3‐tetramethylguanidine) ( L1 , TMG2dmtrien), which combines two weak amine and two strong guanidine donor functions. Two new copper(II) complexes were isolated and structurally characterized as complexes [Cu(TMG2dmtrien)][Br]2 · 3MeCN ( C1 [Br]2 · 3MeCN) and [Cu(TMG2dmtrien)][Cl]2 · 3MeCN ( C2 [Cl]2 · 3MeCN). The cations C1 and C2 [Cu(TMG2dmtrien)]2+ show a square‐planar coordination environment and are chiral with both enantiomers being observed in the unit cell. We investigated the application of L1 in copper‐mediated styrene ATRP. L1 shows with CuBr and PEBr as initiator a high polymerization activity according to the polymerization rate. First order kinetics confirm the living character of the polymerization. However, the deviation of molecular weights from theoretical molecular weights and the broad molecular weight distributions hint for a low controlled ATRP. The ATRP with further copper(I) salts {CuCl, [Cu(MeCN)4]BF4 and [Cu(MeCN)4]PF6} and PECl and PEBr as initiators were investigated as well. Herein the use of [Cu(MeCN)4]PF6 with PECl led to promising results. 相似文献
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Peter Fechner Oliver Bleher Melanie Ewald Kathrin Freudenberger Dominik Furin Urs Hilbig Felix Kolarov Katrin Krieg Lothar Leidner Goran Markovic Günther Proll Florian Pröll Sabrina Rau Johannes Riedt Barbara Schwarz Patricia Weber Julia Widmaier 《Analytical and bioanalytical chemistry》2014,406(17):4033-4051
This review is focused on methods for detecting small molecules and, in particular, the characterisation of their interaction with natural proteins (e.g. receptors, ion channels). Because there are intrinsic advantages to using label-free methods over labelled methods (e.g. fluorescence, radioactivity), this review only covers label-free techniques. We briefly discuss available techniques and their advantages and disadvantages, especially as related to investigating the interaction between small molecules and proteins. The reviewed techniques include well-known and widely used standard analytical methods (e.g. HPLC-MS, NMR, calorimetry, and X-ray diffraction), newer and more specialised analytical methods (e.g. biosensors), biological systems (e.g. cell lines and animal models), and in-silico approaches. 相似文献
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Nitrogen uptake of nickel free austenitic stainless steel powder during heat treatment—an XPS study 下载免费PDF全文
Anna Weddeling Kathrin Lefor Eduard Hryha Stephan Huth Lars Nyborg Sebastian Weber Werner Theisen 《Surface and interface analysis : SIA》2015,47(3):413-422
In austenitic stainless steel nitrogen stabilizes the austenitic phase, improves the mechanical properties and increases the corrosion resistance. Nitrogen alloying enables to produce austenitic steels without the element nickel which is high priced and classified as allergy inducing. A novel production route is nitrogen alloying of CrMn‐prealloyed steel powder via the gas phase. This is beneficial as the nitrogen content can be adjusted above the amount that is reached during conventional casting. A problem which has to be overcome is the oxide layer present on the powder surface which impedes both the sintering process and the uptake of nitrogen. This study focuses on whether heat treatment under pure nitrogen is an appropriate procedure to enable sintering and nitrogen uptake by reduction of surface oxides. X‐ray photoelectron spectroscopy (XPS) in combination with scanning electron microscopy (SEM) and energy dispersive X‐ray spectrometry (EDS) are used to investigate the surface of powdered FeMn19Cr17C0.4N heat treated under nitrogen atmosphere. The analyses showed reduction of iron oxides already at 500 °C leading to oxide‐free metallic surface zones. Mn and Cr oxides are reduced at higher temperatures. Distinct nitrogen uptake was registered, and successful subsequent sintering was reached. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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Nannocystin A: an Elongation Factor 1 Inhibitor from Myxobacteria with Differential Anti‐Cancer Properties 下载免费PDF全文
Philipp Krastel Silvio Roggo Markus Schirle Nathan T. Ross Francesca Perruccio Peter Aspesi Jr. Thomas Aust Kathrin Buntin David Estoppey Brigitta Liechty Felipa Mapa Klaus Memmert Howard Miller Xuewen Pan Ralph Riedl Christian Thibaut Jason Thomas Trixie Wagner Eric Weber Xiaobing Xie Esther K. Schmitt Dr. Dominic Hoepfner 《Angewandte Chemie (International ed. in English)》2015,54(35):10149-10154
Cultivation of myxobacteria of the Nannocystis genus led to the isolation and structure elucidation of a class of novel cyclic lactone inhibitors of elongation factor 1. Whole genome sequence analysis and annotation enabled identification of the putative biosynthetic cluster and synthesis process. In biological assays the compounds displayed anti‐fungal and cytotoxic activity. Combined genetic and proteomic approaches identified the eukaryotic translation elongation factor 1α (EF‐1α) as the primary target for this compound class. Nannocystin A ( 1 ) displayed differential activity across various cancer cell lines and EEF1A1 expression levels appear to be the main differentiating factor. Biochemical and genetic evidence support an overlapping binding site of 1 with the anti‐cancer compound didemnin B on EF‐1α. This myxobacterial chemotype thus offers an interesting starting point for further investigations of the potential of therapeutics targeting elongation factor 1. 相似文献
69.
Dr. Kathrin I. Mohr Dr. Carsten Volz Dr. Rolf Jansen Dr. Victor Wray Dr. Judith Hoffmann Dipl.‐Ing. Steffen Bernecker Priv.‐Doz. Dr. Joachim Wink Dr. Klaus Gerth Prof. Dr. Marc Stadler Prof. Dr. Rolf Müller 《Angewandte Chemie (International ed. in English)》2015,54(38):11254-11258
Lantibiotics (lanthionine‐containing antibiotics) from Gram‐positive bacteria typically exhibit activity against Gram‐positive bacteria. The activity and structure of pinensin A ( 1 ) and B ( 2 ), lantibiotics isolated from a native Gram‐negative producer Chitinophaga pinensis are described. Surprisingly, the pinensins were found to be highly active against many filamentous fungi and yeasts but show only weak antibacterial activity. To the best of our knowledge, lantibiotic fungicides have not been described before. An in‐depth bioinformatic analysis of the biosynthetic gene cluster established the ribosomal origin of these compounds and identified candidate genes encoding all of the enzymes required for post‐translational modification. Additional encoded functions enabled us to build up a hypothesis for the biosynthesis, export, sensing, and import of this intriguing lantibiotic. 相似文献
70.
Stilbenes and zeranol are nonsteroidal estrogenic growth promoters which are banned in the European Union (EU) for use in
food-producing animals by Council Directive 96/22/EC. A liquid chromatography–tandem mass spectrometry (LC-MS/MS) method was
developed for the screening and confirmation of stilbenes (diethylstilbestrol, dienestrol, hexestrol) and resorcylic acid
lactones (zeranol and its metabolites taleranol and zearalanone as well as the mycotoxins α-zearalenol, β-zearalenol and zearalenone)
in bovine urine. The method permits the confirmation and quantification of stilbenes and resorcylic acid lactones at levels
below 1 μg L−1 and 1.5 μg L−1, respectively. The validation was carried out according to Commission Decision 2002/657/EC, Chap. 3.1.3 “alternative validation”
by a matrix-comprehensive in-house validation concept. Decision limit CCα, detection capability CCβ, recovery, repeatabiliy,
within-laboratory reproducibility and the uncertainty of measurement were calculated. Furthermore, a factorial effect analysis
was carried out to identify factors that have a significant influence on the method. Factors considered to be relevant for
the method in routine analysis (e.g. operator, matrix condition, storage duration of the extracts before measurement, different
cartridge lots, hydrolysis conditions) were systematically varied on two levels. The factorial analysis showed that different
cartridge lots, storage durations and matrix conditions can exert a relevant influence on the method. 相似文献