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51.
52.
The study of biologically active natural products has resulted in seminal contributions to our understanding of living systems. In the case of electrophilic natural products, the covalent nature of their interaction has largely facilitated the identification of their biological binding partners. In this review, we provide a comprehensive compilation of electrophilic natural products from all major chemical classes together with their biological targets. Covering Michael acceptor systems, ring-strained compounds and other electrophiles, such as esters or carbamates, we highlight representative and instructive examples for over 20 electrophilic moieties. The fruitful cooperation of natural product chemistry, medicinal chemistry and chemical biology has produced a collection of well-studied examples for how electrophilic natural products exert their biological functions that range from antibiotic to antitumor effects. Special emphasis is put on the elucidation of their respective biological targets via activity-based protein profiling, which together with the recent advancements in mass spectrometry has been crucial to the success of the field. The wealth of naturally occurring electrophilic moieties and their chemical complexity enables binding of a large variety of biological targets, such as enzymes of all classes, nonenzymatic proteins, DNA and other cellular compounds. With approximately 30,000 genes in the human genome but only 266 confirmed protein drug targets, the study of biologically active, electrophilic natural products has the potential to provide insights into fundamental biological processes and to greatly aid the discovery of new drug targets. 相似文献
53.
Singh V Azarkh M Drescher M Hartig JS 《Chemical communications (Cambridge, England)》2012,48(66):8258-8260
G-quadruplex conformations within a sequence of three quadruplex units of human telomeric DNA were studied by two-frequency pulsed electron paramagnetic resonance (EPR) spectroscopy. In contrast to some individual G-quadruplexes, within the higher-order human telomeric sequence a (3+1) hybrid structure is formed. 相似文献
54.
Malte Sellin Christian Friedmann Maximilian Maylnder Sabine Richert Ingo Krossing 《Chemical science》2022,13(32):9147
To access the hitherto almost unknown class of clustered transition metal carbonyl cations, the trimetal dodecacarbonyls M3(CO)12 (M = Ru, Os) were reacted with the oxidant Ag+[WCA]−, but yielded the silver complexes [Ag{M3(CO)12}2]+[WCA]− (WCA = [Al(ORF)4]−, [F{Al(ORF)3}2]−; RF = –OC(CF3)3). Addition of further diiodine I2 to increase the redox potential led for M = Ru non-specifically to divalent mixed iodo-RuII-carbonyl cations. With [NO]+, even the N–O bond was cleaved and led to the butterfly carbonyl complex cation [Ru4N(CO)13]+ in low yield. Obviously, ionization of M3(CO)12 with retention of its pseudo-binary composition including only M and CO is difficult and the inorganic reagents did react non-innocently. Yet, the radical cation of the commercially available perhalogenated anthracene derivative 9,10-dichlorooctafluoroanthracene (anthraceneHal) is a straightforward accessible innocent deelectronator with a half-wave potential E1/2 of 1.42 V vs. Fc0/+. It deelectronates M3(CO)12 under a CO atmosphere and leads to the structurally characterized cluster salts [M3(CO)14]2+([WCA]−)2 including a linear M3 chain. The structural characterization as well as vibrational and NMR spectroscopies indicate the presence of three electronically independent sets of carbonyl ligands, which almost mimic M(CO)5, free CO and even [M(CO)6]2+ in one and the same cation.Trimeric M3(CO)12 (M = Ru, Os) reacts with typical inorganic oxidants to unwanted side products. Yet, the 9,10-dichlorooctafluoroanthracene radical cation deelectronates these under CO pressure to give the first homotrimetallic [M3(CO)14]2+ salts. 相似文献
55.
Malte Bayer Linus Angenendt Christoph Schliemann Wolfgang Hartmann Simone Knig 《Journal of mass spectrometry : JMS》2020,55(8)
Formalin‐fixed and paraffin‐embedded (FFPE)–tissue archives are potential treasure troves in the search for clinically interesting specimens. However, while the FFPE‐treatment provides excellent conservation of the three‐dimensional structure of the tissue and prevents degradation over decades, it also introduces numerous nonspecific and irreversible protein modifications. In this study, we have evaluated several published workflows for FFPE‐tissue by fit‐for‐purpose proteomics technologies. We demonstrate that many protein modifications and cross‐links remain after treatment and conclude that the proteomics of FFPE‐tissue is of value, but clear‐cut limitations must be kept in mind. The analysis of abundant proteins in FFPE is straightforward, but confident identification of low‐level proteins and/or biologically relevant modifications is seriously hampered by the FFPE‐treatment. Peptide assignment should only be performed on high‐quality spectra, even if this is at the cost of lower numbers of protein IDs. As Yergey and Coorssen stated in 2015: “Data quality is considered the primary criterion, and we thus emphasize that the standards of Analytical Chemistry must apply throughout any proteomic analysis.” 相似文献
56.
57.
Dr. Xin Chen Malte Kohring Dr. M'hamed Assebban Dr. Bartłomiej Tywoniuk Dr. Cian Bartlam Narine Moses Badlyan Prof. Janina Maultzsch Prof. Georg S. Duesberg Prof. Heiko B. Weber Dr. Kathrin C. Knirsch Prof. Andreas Hirsch 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(52):13117-13122
The development of an efficient method to patterning 2D MoS2 into a desired topographic structure is of particular importance to bridge the way towards the ultimate device. Herein, we demonstrate a patterning strategy by combining the electron beam lithography with the surface covalent functionalization. This strategy allows us to generate delicate MoS2 ribbon patterns with a minimum feature size of 2 μm in a high throughput rate. The patterned monolayer MoS2 domain consists of a spatially well-defined heterophase homojunction and alternately distributed surface characteristics, which holds great interest for further exploration of MoS2 based devices. 相似文献
58.
59.
Hybrid approach to the synthesis of highly luminescent CdTe/ZnS and CdHgTe/ZnS nanocrystals 总被引:2,自引:0,他引:2
Tsay JM Pflughoefft M Bentolila LA Weiss S 《Journal of the American Chemical Society》2004,126(7):1926-1927
We report the synthesis of highly luminescent CdTe/ZnS and CdHgTe/ZnS core/shell semiconductor nanocrystals (NCs). A hybrid of two synthesis routes leads to novel nanocrystal compositions and small core/shell sizes (4-5 nm) that emit in the far-red and near-infrared regions. These particles exhibit higher resistance to oxidation and photobleaching, have high quantum yields, and could be used for biological labeling and imaging. 相似文献
60.
Malte E. Helmbold 《Zeitschrift für Physik A Hadrons and Nuclei》1976,76(1):9-14
In an atomic beam experiment we measured the hyperfine structure (hfs) of the metastable states 3d
2 4s
4
F
3/2,9/2 of Scandium, which were populated by electron impact. A single mode cw dye laser was used to create a population difference between neighbouring hfs states by optical pumping. Rf transitions between these states, equalizing the population numbers, could then be detected by repeating the optical pumping experiment and looking for the laser induced fluorescent light. The following constants of the magnetic dipole and electric quadrupole interactions have been obtained by this method:A
3/2=–158.513(3)MHzB
3/2=–5.19(2)MHzA
9/2=285.967(9)MHzB
9/2=–15.46(70)MHzFrom these constants and the corresponding values forJ=5/2, 7/2, as measured by [1], the following parameters can be calculated: r
–3
d
01
=0.911(4)a
0
–3
r
–3
d
12
=2.395 (62)a
0
–3
and:=r
–3
d
01
/r
–3
d
12
=0.38(1). 相似文献