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211.
Frank Kirschhöfer Annika Rieder Carolin Prechtl Boris Kühl Kristina Sabljo Christof Wöll Ursula Obst Gerald Brenner-Weiß 《Analytica chimica acta》2013
Proteinaceous conditioning films (pCFs) are thought to play a key role in microbial adhesion, leading to the fouling of technical and biomedical devices and biofilm formation, which in turn causes material damage or persistent infections, respectively. However, little is definitively known about the process of surface conditioning via proteins. Herein, we demonstrate the potential of quartz crystal microbalance with dissipation coupled to MALDI-ToF mass spectrometry (QCM-D-MALDI) to investigate protein adsorption on different surfaces, enabling both the monitoring of CF formation and the determination of the molecular composition of CFs. After running QCM-D experiments, a subsequent tryptic on chip digestion step allows the identification of the proteins deposited on the sensor chip surface via MALDI-ToF mass spectrometry. Prominent blood plasma proteins, i.e., human serum albumin (HSA), fibrinogen (FG) and fibronectin (FN), were used. Chemically well defined sensor surfaces were prepared, among others, via self-assembled monolayer (SAM) technology. In cases where protein adsorption was observed by QCM-D, the adsorbed proteins were clearly detected and identified using MALDI-ToF/MS for both single-protein solutions of HSA, FG and FN as well as for protein mixtures. However, for equimolar protein mixtures on TiO2 surfaces, only signals attributed to FG and FN were observed in the mass spectra. No signals indicating the presence of HSA could be detected. This finding leads to the assumption that only FG and FN attach to the TiO2 sensor surface under the given experimental conditions. 相似文献
212.
Madwar C Kwan WC Deng L Ramström O Schmidt R Zou S Cuccia LA 《Langmuir : the ACS journal of surfaces and colloids》2010,26(22):16677-16680
The versatility of perfluorophenyl azide (PFPA) derivatives makes them useful for attaching a wide variety of biomolecules and polymers to surfaces. Herein, a single molecule force spectroscopy (SMFS) study of the concanavalin A/mannose interaction was carried out using PFPA immobilization chemistry. SMFS of the concanavalin A/mannose interaction yielded an average unbinding force of 70-80 pN for loading rates between 8000 and 40,000 pN/s for mannose surfaces on aminated glass, and an unbinding force of 57 ± 20 pN at 6960 pN/s for mannose surfaces on gold-coated glass. Dynamic force spectroscopy was used to determine the dissociation rate constant, k(off), for this interaction to be 0.16 s(-1). 相似文献
213.
Carolin Schwehm William Lewis Alexander J. Blake Barrie Kellam Michael J. Stocks 《Acta Crystallographica. Section C, Structural Chemistry》2014,70(12):1161-1168
Bicycle ring closure on a mixture of (4aS,8aR)‐ and (4aR,8aS)‐ethyl 2‐oxodecahydro‐1,6‐naphthyridine‐6‐carboxylate, followed by conversion of the separated cis and trans isomers to the corresponding thioamide derivatives, gave (4aSR,8aRS)‐ethyl 2‐sulfanylidenedecahydro‐1,6‐naphthyridine‐6‐carboxylate, C11H18N2O2S. Structural analysis of this thioamide revealed a structure with two crystallographically independent conformers per asymmetric unit (Z′ = 2). The reciprocal bicycle ring closure on (3aRS,7aRS)‐ethyl 2‐oxooctahydro‐1H‐pyrrolo[3,2‐c]pyridine‐5‐carboxylate, C10H16N2O3, was also accomplished in good overall yield. Here the five‐membered ring is disordered over two positions, so that both enantiomers are represented in the asymmetric unit. The compounds act as key intermediates towards the synthesis of potential new polycyclic medicinal chemical structures. 相似文献
214.
Bernhard Valldorf Heiko Fittler Lukas Deweid Aileen Ebenig Stephan Dickgiesser Carolin Sellmann Janine Becker Stefan Zielonka Dr. Martin Empting Dr. Olga Avrutina Prof. Dr. Harald Kolmar 《Angewandte Chemie (International ed. in English)》2016,55(16):5085-5089
Multivalent ligands of death receptors hold particular promise as tumor cell‐specific therapeutic agents because they induce an apoptotic cascade in cancerous cells. Herein, we present a modular approach to generate death receptor 5 (DR5) binding constructs comprising multiple copies of DR5 targeting peptide (DR5TP) covalently bound to biomolecular scaffolds of peptidic nature. This strategy allows for efficient oligomerization of synthetic DR5TP‐derived peptides in different spatial orientations using a set of enzyme‐promoted conjugations or recombinant production. Heptameric constructs based on a short (60–75 residues) scaffold of a C‐terminal oligomerization domain of human C4b binding protein showed remarkable proapoptotic activity (EC50=3 nm ) when DR5TP was ligated to its carboxy terminus. Our data support the notion that inter‐ligand distance, relative spatial orientation and copy number of receptor‐binding modules are key prerequisites for receptor activation and cell killing. 相似文献
215.
Hannes Georg Graf Sonja Maria Biebl Linda Müller Christina Breitenstein Carolin Huhn 《Journal of separation science》2022,45(5):1128-1139
Thermodynamic acidity constants and limiting ionic mobilities were determined for polyprotic non-chromophore analytes using capillary electrophoresis with capacitively coupled contactless conductivity detection. It was not necessary to work with buffers of identical ionic strength as ionic strength effects on effective electrophoretic mobilities were corrected by modeling during data evaluation (software AnglerFish). The mobility data from capillary electrophoresis coupled to conductivity detection were determined in the pH range from 1.25 to 12.02 with a high resolution (36 pH steps). With this strategy, thermodynamic acidity constants and limiting ionic mobilities for various acidic herbicides were determined, sometimes for the first time. The model analytes included glyphosate, its metabolites, and its acetylated derivates (aminomethyl phosphonic acid, glyoxylic acid, sarcosine, glycine, N-acetyl glyphosate, N-acetyl aminomethyl phosphonic acid, hydroxymethyl phosphonic acid). The obtained data were used in simulations to optimize separations by capillary electrophoresis. Simulations correlated very well to experimental results. With the new method, the separation of glyphosate from interfering components like phosphate in beer samples was possible. 相似文献
216.
Previous studies on the sensitivity of cracks in ice shelves with different boundary conditions, stress states and density profiles revealed the need for further analyses. As the transfer of boundary conditions from dynamic ice flow simulations to the linear elastic fracture analyses proved to be a critical point in previous studies, a new approach to relate viscous and elastic material behaviour is proposed. The numerical simulations are conducted using Finite Elements utilizing the concept of configurational forces. To show the applicability of the approach, a 2-dimensional plane stress geometry with volume loads due to the ice shelf flow is analyzed. The resulting crack path is compared to available crack paths from satellite images. (© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
217.
In this paper, the stability of fractional differential equations is addressed. A criterion for the identification of spurious modes is derived. Two techniques for the a posteriori elimination of the corresponding solution parts are presented. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献