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排序方式: 共有138条查询结果,搜索用时 16 毫秒
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The binding of enantiomeric haptens and transition states by the Schultz Diels-Alderase antibody 39A11 and its germ-line antibody were studied theoretically. The mechanisms by which one hapten and one transition state stereoisomer is recognized selectively are explored with docking simulations and quantum mechanical models. Transition states of the relevant Diels-Alder reaction were located with density functional theory. A prediction is made that the stereoselectivity of 39A11 will be achieved by two strategically placed hydrogen bonds and pi-stacking interactions of the maleimide with a binding-site tryptophan, arranged so as to coordinate one enantiomeric transition state. Binding of other ligands by antibody 39A11 and the germ-line antibody has also been investigated. The polyspecific nature of 39A11 and its germ-line precursor was found to originate from the general ability of the binding pockets to achieve hydrophobic binding of small organic substrates. Comparison of the highly homologous progesterone and Diels-Alderase antibodies (DB3, 1E9, and 39A11) highlights the fact that differences of several key residues in the binding pockets are sufficient to confer selectivity for different antigens. 相似文献
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Sandy AR Mochrie SG Zehner DM Grübel G Huang KG Gibbs D 《Physical review letters》1992,68(14):2192-2195
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Hong Sun Frederick Roussel Wing Shun Cheung B. M. Fung Sandy S. Keast Mark Lohman 《Liquid crystals》2013,40(10):1483-1486
Liquid crystals (LCs) with diazo linkages have high dielectric and optical anisotropy. Two newly synthesized liquid crystalline compounds were dissolved in room temperature LC hosts, E7 and PTTP-24/36, to assess their properties. It was found that these mixtures have higher birefringence, larger dielectric anisotropy, and better elastic properties than the hosts. Satisfactory viscoelastic coefficients were also obtained for these mixtures, showing that they are promising LC materials for applications in the near IR region. 相似文献
6.
A. F. Isakovic A. Stein J. B. Warren S. Narayanan M. Sprung A. R. Sandy K. Evans‐Lutterodt 《Journal of synchrotron radiation》2009,16(1):8-13
Motivated by the anticipated advantageous performance of diamond kinoform refractive lenses for synchrotron X‐ray radiation studies, this report focuses on progress in designing, nanofabricating and testing of their focusing performance. The method involves using lift‐off and plasma etching to reproduce a planar definition of numerically determined kinoform refractive optics. Tests of the focusing action of a diamond kinoform refractive lens at the APS 8‐ID‐I beamline demonstrate angular control of the focal spot. 相似文献
7.
Diamino‐ and diazidofuranoses represent useful precursors, for example, for the synthesis of substituted nucleosides and metal complexes, respectively. Known procedures for their synthesis lack the availability of cheap starting materials, adequate yields, and the access to all possible diastereomeres. Therefore, 3,5‐diazido‐3,5‐dideoxy‐ and ‐2,3,5‐trideoxyfuranoses both with ribo‐ and xylo‐configuration were prepared using different approaches. 相似文献
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Sandy Theysgeur Benoit Cudennec Barbara Deracinois Claire Perrin Isabelle Guiller Anne Lepoudre Christophe Flahaut Rozenn Ravallec 《Molecules (Basel, Switzerland)》2021,26(1)
Like their owners, dogs and cats are more and more affected by overweight and obesity-related problems and interest in functional pet foods is growing sharply. Through numerous studies, fish protein hydrolysates have proved their worth to prevent and manage obesity-related comorbidities like diabetes. In this work, a human in vitro static simulated gastrointestinal digestion model was adapted to the dog which allowed us to demonstrate the promising effects of a tilapia byproduct hydrolysate on the regulation of food intake and glucose metabolism. Promising effects on intestinal hormones secretion and dipeptidyl peptidase IV (DPP-IV) inhibitory activity were evidenced. We identify new bioactive peptides able to stimulate cholecystokinin (CCK) and glucagon-like peptide 1 (GLP-1) secretions, and to inhibit the DPP-IV activity after a transport study through a Caco-2 cell monolayer. 相似文献
9.
Carla Kirschbaum Essa M. Saied Kim Greis Eike Mucha Sandy Gewinner Wieland Schllkopf Gerard Meijer Gert von Helden Berwyck L. J. Poad Stephen J. Blanksby Christoph Arenz Kevin Pagel 《Angewandte Chemie (International ed. in English)》2020,59(32):13638-13642
1‐Deoxysphingolipids are a recently described class of sphingolipids that have been shown to be associated with several disease states including diabetic and hereditary neuropathy. The identification and characterization of 1‐deoxysphingolipids and their metabolites is therefore highly important. However, exact structure determination requires a combination of sophisticated analytical techniques due to the presence of various isomers, such as ketone/alkenol isomers, carbon–carbon double‐bond (C=C) isomers and hydroxylation regioisomers. Here we demonstrate that cryogenic gas‐phase infrared (IR) spectroscopy of ionized 1‐deoxysphingolipids enables the identification and differentiation of isomers by their unique spectroscopic fingerprints. In particular, C=C bond positions and stereochemical configurations can be distinguished by specific interactions between the charged amine and the double bond. The results demonstrate the power of gas‐phase IR spectroscopy to overcome the challenge of isomer resolution in conventional mass spectrometry and pave the way for deeper analysis of the lipidome. 相似文献
10.
Ana Isabel González Flórez Eike Mucha Dr. Doo‐Sik Ahn Sandy Gewinner Dr. Wieland Schöllkopf Prof. Dr. Kevin Pagel Dr. Gert von Helden 《Angewandte Chemie (International ed. in English)》2016,55(10):3295-3299
Here we present a combined experimental and theoretical study on the secondary structure of isolated proteins as a function of charge state. In infrared spectra of the proteins ubiquitin and cytochrome c, amide I (C=O stretch) and amide II (N–H bend) bands can be found at positions that are typical for condensed‐phase proteins. For high charge states a new band appears, substantially red‐shifted from the amide II band observed at lower charge states. The observations are interpreted in terms of Coulomb‐driven transitions in secondary structures from mostly helical to extended C5‐type hydrogen‐bonded structures. Support for this interpretation comes from simple energy considerations as well as from quantum chemical calculations on model peptides. This transition in secondary structure is most likely universal for isolated proteins that occur in mass spectrometric experiments. 相似文献