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151.
Kevin F. Morris Eugene J. Billiot Fereshteh H. Billiot Jordan A. Ingle Kevin B. Krause Corbin R. Lewis 《Journal of Dispersion Science and Technology》2019,40(5):716-727
Molecular dynamics (MD) simulations were used to investigate the binding of six chiral compounds to the amino acid-based molecular micelle (MM) poly-(sodium undecyl-(L)-leucine-leucine) or poly(SULL). The MM investigated is used as a chiral selector in capillary electrophoresis. The project goal was to characterize the chiral recognition mechanism in these separations and to move toward predictive models to identify the best amino acid-based MM for a given separation. Poly(SULL) was found to contain six binding sites into which chiral compounds could insert. Four sites had similar sizes, shapes, and electrostatic properties. Enantiomers of alprenolol, propranolol, 1,1′-bi-2-naphthyl-2,2′-diyl hydrogen phosphate, 1,1′-bi-2-naphthol, chlorthalidone, or lorazepam were separately docked into each binding pocket and MD simulations with the resulting intermolecular complexes were performed. Solvent-accessible surface area calculations showed the compounds preferentially associated with binding sites where they penetrated into the MM core and shielded their non-polar atoms from solvent. Furthermore, with five of the six compounds the enantiomer with the most favorable free energy of MM association also experienced the most favorable intermolecular hydrogen bonding interactions with the MM. This result suggests that stereoselective intermolecular hydrogen bonds play an important role in chiral discrimination in separations using amino acid-based MMs.GRAPHICAL ABSTRACT 相似文献
152.
The two new compounds [Fe(tren)]FeSbS4 ( 1 ) (tren = tris(2‐aminoethyl)amine) and [Fe(dien)2]Fe2Sb4S10 ( 2 ) (dien = diethylendiamine) were prepared under solvothermal conditions and represent the first thioantimonates(III) with iron cations integrated into the anionic network. In both compounds Fe3+ is part of a [2FeIII‐2S] cluster which is often found in ferredoxines. In addition, Fe2+ ions are present which are surrounded by the organic ligands. In ( 1 ) the Fe2+ ion is also part of the thioantimonate(III) network whereas in ( 2 ) the Fe2+ ion is isolated. In both compounds the primary SbS3 units are interconnected into one‐dimensional chains. The mixed‐valent character of [Fe(tren)]FeSbS4 was unambiguously determined with Mössbauer spectroscopy. Both compounds exhibit paramagnetic behaviour and for ( 1 ) a deviation from linearity is observed due to a strong zero‐field splitting. Both compounds decompose in one single step. 相似文献
153.
This article describes the identification of the autophosphorylation sites of the G protein-sensitive class I phosphoinositide 3-kinase isoforms beta and gamma by mass spectrometry. Since discrimination and suppression effects prevented the immediate detection and sequencing of phosphopeptides in complex mixtures, a strategy was applied that involved (32)P-radiolabeling of the phosphoproteins, cleavage of the phosphoproteins with several proteases and/or cyanogen bromide, separation of the resulting peptide mixtures by micro-reversed-phase liquid chromatography, and mass spectrometric analysis of fractions containing phosphopeptides. As a result the primary autophosphorylation sites of phosphoinositide 3-kinase p110beta and p110gamma subunits could be unambiguously assigned to the C-terminal Ser 1070 and Ser 1101, respectively. 相似文献
154.
155.
Since the early reports of MOFs and their interesting properties, research involving these materials has grown wide in scope and applications. Various synthetic approaches have ensued in view of obtaining materials with optimised properties, the extensive scope of application spanning from energy, gas sorption, catalysis biological applications has meant exponentially evolved over the years. The far‐reaching synthetic and PSM approaches and porosity control possibilities have continued to serve as a motivation for research on these materials. With respect to the biological applications, MOFs have shown promise as good candidates in applications involving drug delivery, BioMOFs, sensing, imaging amongst others. Despite being a while away from successful entry into the market, observed results in sensing, drug delivery, and imaging put these materials on the spot light as candidates poised to usher in a revolution in biology. In this regard, this review article focuses current approaches in synthesis, post functionalization and biological applications of these materials with particular attention on drug delivery, imaging, sensing and BioMOFs. 相似文献
156.
Fangyuan Zhang Evripidis Michail Fridolin Saal Ana-Maria Krause Dr. Prince Ravat 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(71):16241-16245
Herein, we have synthesized an enantiomerically pure propeller-shaped PAH, C90H48, possessing three [7]helicene and three [5]helicene subunits. This compound can be obtained in gram quantities in a straightforward manner. The photophysical and chiroptical properties were investigated using UV/Vis absorption and emission, optical rotation and circular dichroism spectroscopy, supported by DFT calculations. The nonlinear optical properties were investigated by two-photon absorption measurements using linearly and circularly polarized light. The extremely twisted structure and packing of the homochiral compound were investigated by single-crystal X-ray diffraction analysis. 相似文献
157.
On the Mechanism of Sequential Radical Cyclization of (Bromomethyl)silyl Ethers of Terpernoid Alcohols The cyclic products of the Bu3SnH-promoted radical reaction of (E)-1-[(bromomethyl)dimethylsilyloxy]-2-methylhept-2-ene ( 6 ) consists to 98% of a 1:2 mixture of (±)-(4RS,5RS)- and (±)-(4-RS,5SR)-4-butyl-2,2,5-trimethyl-1-oxa-2-silacyclohexane ( 8a and 8b , respectively). It is, therefore, concluded that the 6-‘endo’→5-‘exo’ tandem cyclization of the 5-mehtyl-3-oxa-2-siladeca-5,9-dien-l-yl radical (reaction 1 → 2 ) is not necessarily a concerted process, but may be explained as a sequence of individual steps via free-radical intermediates. 相似文献
158.
159.
Mandy Eibisch Sebastian Zellmer Rolf Gebhardt Rosmarie Süß Beate Fuchs Jürgen Schiller 《Rapid communications in mass spectrometry : RCM》2011,25(18):2619-2626
The liver is an important organ that is particularly involved in the lipid metabolism of the organism. Thus, high interest is nowadays focused on the lipid composition of the liver and particularly the liver parenchymal cells, the hepatocytes. Hepatocytes contain common phospholipids (PL) such as phosphatidylcholines, ‐ethanolamines and ‐inositols, for instance, that can be easily analyzed by matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOF MS) even without previous separation of the PL mixture. However, in addition to common PL, hepatocytes possess also significant amounts of cardiolipin (CLP). The MS analysis of this PL is quite challenging because it (a) has a higher mass than common lipids and (b) possesses a higher negative charge. We will show here that caution is required if CLP is analyzed directly from the total lipid extract because PC dimers may be interpreted as cardiolipins if the positive ion MALDI mass spectra are analyzed. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
160.
Identification and analysis of the core biosynthetic machinery of tubulysin, a potent cytotoxin with potential anticancer activity 总被引:4,自引:0,他引:4
Myxobacteria are well known for their biosynthetic potential, especially for the production of cytotoxic compounds with potential anticancer activities. The tubulysins are currently in preclinical development. They are produced in very low quantities, and genetic manipulation of producing strains has never been accomplished. We report the development of a mariner-based transposon mutagenesis system for Angiococcus disciformis An d48. Extracts from a library of 1200 mutants were analyzed for the presence of tubulysin by a microscopic cell nucleus fragmentation bioassay. The transposition sites of four tubulysin-negative mutants were identified by vector recovery, which led to the identification and the sequencing of the corresponding core biosynthetic gene locus. Sequence analysis of more than 80,000 bp reveals an unusual multimodular hybrid polyketide synthase/peptide synthetase assembly line with a variety of unprecedented features. 相似文献