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排序方式: 共有520条查询结果,搜索用时 15 毫秒
91.
Katrin Sophie Bohnsack Marika Kaden Julia Abel Sascha Saralajew Thomas Villmann 《Entropy (Basel, Switzerland)》2021,23(10)
In the present article we propose the application of variants of the mutual information function as characteristic fingerprints of biomolecular sequences for classification analysis. In particular, we consider the resolved mutual information functions based on Shannon-, Rényi-, and Tsallis-entropy. In combination with interpretable machine learning classifier models based on generalized learning vector quantization, a powerful methodology for sequence classification is achieved which allows substantial knowledge extraction in addition to the high classification ability due to the model-inherent robustness. Any potential (slightly) inferior performance of the used classifier is compensated by the additional knowledge provided by interpretable models. This knowledge may assist the user in the analysis and understanding of the used data and considered task. After theoretical justification of the concepts, we demonstrate the approach for various example data sets covering different areas in biomolecular sequence analysis. 相似文献
92.
Jürgen M. Kolos Sebastian Pomplun Sascha Jung Benedikt Rieß Patrick L. Purder Andreas M. Voll Stephanie Merz Monika Gnatzy Thomas M. Geiger Ingrid Quist-Lkken Jerome Jatzlau Petra Knaus Toril Holien Andreas Bracher Christian Meyners Paul Czodrowski Vera Krewald Felix Hausch 《Chemical science》2021,12(44):14758
Methyl groups can have profound effects in drug discovery but the underlying mechanisms are diverse and incompletely understood. Here we report the stereospecific effect of a single, solvent-exposed methyl group in bicyclic [4.3.1] aza-amides, robustly leading to a 2 to 10-fold increase in binding affinity for FK506-binding proteins (FKBPs). This resulted in the most potent and efficient FKBP ligands known to date. By a combination of co-crystal structures, isothermal titration calorimetry (ITC), density-functional theory (DFT), and 3D reference interaction site model (3D-RISM) calculations we elucidated the origin of the observed affinity boost, which was purely entropically driven and relied on the displacement of a water molecule at the protein–ligand–bulk solvent interface. The best compounds potently occupied FKBPs in cells and enhanced bone morphogenic protein (BMP) signaling. Our results show how subtle manipulation of the solvent network can be used to design atom-efficient ligands for difficult, solvent-exposed binding pockets.Enhancement by displacement. A single methyl group displaces a water molecule from the binding site of FKBPs, resulting in the most potent binders known, outperforming the natural products FK506 and rapamycin in biochemical and cellular assays. 相似文献
93.
[{Cp″Co}3(μ3-P)(μ3-PSe)], a Trinuclear Cluster with a PSe Ligand The cothermolysis of [Cp″Co(CO)2] ( 1 ), Cp″ = C5H3Bu-1.3, and P4 gives besides [{Cp″Co}3(μ3-P)2] ( 2 ) the cobalt Pn complexes [{Cp″Co}4(μ3-P)4] ( 3 ) and [{Cp″Co}2(μ, η2:2-P2)2] ( 4 ). 2 can be oxidized with grey selenium forming [{Cp″Co}3(μ3-P)(μ3-PSe)] ( 5 ) and [{Cp″Co}3(μ3-PSe)2] ( 6 ), complexes with the hitherto unknown PSe ligand. The crystal structure of 5 reveals a trigonal-bipyramidal Co3P2 skeleton with one μ3-PSe ligand. 相似文献
94.
95.
In the present paper, we describe the first structural characterization of cymantrenyl(dihalo)borane and report on its use for the synthesis of novel cymantrenylboryl complexes. 相似文献
96.
97.
Gärtner F Denurra S Losse S Neubauer A Boddien A Gopinathan A Spannenberg A Junge H Lochbrunner S Blug M Hoch S Busse J Gladiali S Beller M 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(11):3220-3225
Novel phenylazole ligands were applied successfully in the synthesis of cyclometalated iridium(III) complexes of the general formula [Ir(phenylazole)(2)(bpy)]PF(6) (bpy=2,2'-bipyridine). All complexes were fully characterized by NMR, IR, and MS spectroscopic studies as well as by cyclic voltammetry. Three crystal structures obtained by X-ray analysis complemented the spectroscopic investigations. The excited-state lifetimes of the iridium complexes were determined and showed to be in the range of several hundred ns to multiple μs. All obtained iridium complexes were active as photosensitizers in catalytic hydrogen evolution from water in the presence of triethylamine as a sacrificial reducing agent. Applying an in situ formed iron-based water reduction catalyst derived from [HNEt(3)](+) [HFe(3)(CO)(11)](-) and tris[3,5-tris-(trifluoromethyl)-phenyl]phosphine as the ligand, [Ir(2-phenylbenz-oxazole)(2)-(bpy)]PF(6) proved to be the most efficient complex giving a quantum yield of 16% at 440 nm light irradiation. 相似文献
98.
99.
Sebastian O. Klemm Sascha E. Pust Achim Walter Hassel Jürgen Hüpkes Karl J. J. Mayrhofer 《Journal of Solid State Electrochemistry》2012,16(1):283-290
The processes during chemical and electrochemical etching of Al-doped ZnO are investigated utilizing a scanning flow cell
setup with online detection of dissolved Zn ions. The rate of chemical dissolution was found to be a linear function of buffer
and proton concentration in near neutral pH solutions according to a transport limited reaction. In contrast, electrochemical
etching is limited by the kinetics of the reaction and increases linearly with the imposed current density. Due to this fundamental
difference, the dissolution of Zn can be either uniform over the whole surface or highly localized at active sites like grain
boundaries. A combined approach of chemical etching and the well-controllable galvanostatic dissolution thus allows a fine
adjustment of the ZnO:Al surface texture for applications in silicon thin film photovoltaic cells in order to improve their
overall energy conversion efficiency. 相似文献
100.
Deraeve C Guo Z Bon RS Blankenfeldt W DiLucrezia R Wolf A Menninger S Stigter EA Wetzel S Choidas A Alexandrov K Waldmann H Goody RS Wu YW 《Journal of the American Chemical Society》2012,134(17):7384-7391
Post-translational attachment of geranylgeranyl isoprenoids to Rab GTPases, the key organizers of intracellular vesicular transport, is essential for their function. Rab geranylgeranyl transferase (RabGGTase) is responsible for prenylation of Rab proteins. Recently, RabGGTase inhibitors have been proposed to be potential therapeutics for treatment of cancer and osteoporosis. However, the development of RabGGTase selective inhibitors is complicated by its structural and functional similarity to other protein prenyltransferases. Herein we report identification of the natural product psoromic acid (PA) that potently and selectively inhibits RabGGTase with an IC(50) of 1.3 μM. Structure-activity relationship analysis suggested a minimal structure involving the depsidone core with a 3-hydroxyl and 4-aldehyde motif for binding to RabGGTase. Analysis of the crystal structure of the RabGGTase:PA complex revealed that PA forms largely hydrophobic interactions with the isoprenoid binding site of RabGGTase and that it attaches covalently to the N-terminus of the α subunit. We found that in contrast to other protein prenyltransferases, RabGGTase is autoinhibited through N-terminal (α)His2 coordination with the catalytic zinc ion. Mutation of (α)His dramatically enhances the reaction rate, indicating that the activity of RabGGTase is likely regulated in vivo. The covalent binding of PA to the N-terminus of the RabGGTase α subunit seems to potentiate its interaction with the active site and explains the selectivity of PA for RabGGTase. Therefore, psoromic acid provides a new starting point for the development of selective RabGGTase inhibitors. 相似文献