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排序方式: 共有179条查询结果,搜索用时 31 毫秒
61.
Claudius Lenz Jonas Wick Daniel Braga María García‐Altares Gerald Lackner Christian Hertweck Markus Gressler Dirk Hoffmeister 《Angewandte Chemie (International ed. in English)》2020,59(4):1450-1454
Upon injury, psychotropic psilocybin‐producing mushrooms instantly develop an intense blue color, the chemical basis and mode of formation of which has remained elusive. We report two enzymes from Psilocybe cubensis that carry out a two‐step cascade to prepare psilocybin for oxidative oligomerization that leads to blue products. The phosphatase PsiP removes the 4‐O‐phosphate group to yield psilocin, while PsiL oxidizes its 4‐hydroxy group. The PsiL reaction was monitored by in situ 13C NMR spectroscopy, which indicated that oxidative coupling of psilocyl residues occurs primarily via C‐5. MS and IR spectroscopy indicated the formation of a heterogeneous mixture of preferentially psilocyl 3‐ to 13‐mers and suggest multiple oligomerization routes, depending on oxidative power and substrate concentration. The results also imply that phosphate ester of psilocybin serves a reversible protective function. 相似文献
62.
Xiaoyang Shi Hang Xiao Prof. Klaus S. Lackner Prof. Xi Chen 《Angewandte Chemie (International ed. in English)》2016,55(12):4026-4029
Water confined in nanoscopic pores is essential in determining the energetics of many physical and chemical systems. Herein, we report a recently discovered unconventional, reversible chemical reaction driven by water quantities in nanopores. The reduction of the number of water molecules present in the pore space promotes the hydrolysis of CO32? to HCO3? and OH?. This phenomenon led to a nano‐structured CO2 sorbent that binds CO2 spontaneously in ambient air when the surrounding is dry, while releasing it when exposed to moisture. The underlying mechanism is elucidated theoretically by computational modeling and verified by experiments. The free energy of CO32? hydrolysis in nanopores reduces with a decrease of water availability. This promotes the formation of OH?, which has a high affinity to CO2. The effect is not limited to carbonate/bicarbonate, but is extendable to a series of ions. Humidity‐driven sorption opens a new approach to gas separation technology. 相似文献
63.
Dr. Tyler K. Allred Dr. André P. Dieskau Dr. Peng Zhao Dr. Gregory L. Lackner Prof. Larry E. Overman 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(15):6327-6331
The enantioselective total synthesis of the rearranged spongian diterpenoid (−)-macfarlandin C is reported. This is the first synthesis of a rearranged spongian diterpenoid in which the bulky hydrocarbon fragment is joined via a quaternary carbon to the highly hindered concave face of the cis-2,8-dioxabicyclo[3.3.0]octan-3-one moiety. The strategy involves a late-stage fragment coupling between a tertiary carbon radical and an electrophilic butenolide resulting in the stereoselective formation of vicinal quaternary and tertiary stereocenters. A stereoselective Mukaiyama hydration that orients a pendant carboxymethyl side chain cis to the bulky octahydronapthalene substituent was pivotal in fashioning the challenging concave-substituted cis-dioxabicyclo[3.3.0]octanone fragment. 相似文献
64.
K Scherlach B Busch G Lackner U Paszkowski C Hertweck 《Angewandte Chemie (International ed. in English)》2012,51(38):9615-9618
Division of labor: A combination of genetic, microbial, and chemical analyses solved the riddle of the dual epoxidation in the biosynthesis of rhizoxin, the causative agent of rice seedling blight. Bacterial endosymbionts of Rhizopus microsporus mediate the first epoxidation by a dedicated cytochrome P450 monooxygenase. The second oxirane ring is introduced by the fungal host and results in a substantially increased potency of the phytotoxin. 相似文献
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66.
K.S. Lackner 《The European physical journal. Special topics》2009,176(1):93-106
Carbon dioxide capture from ambient air could compensate for all carbon dioxide emissions to the atmosphere. Such capture
would, for example, make it possible to use liquid, carbon-based fuels in cars or airplanes without negatively impacting the
climate. We present a specific approach based on a solid sorbent in the form of an anionic exchange resin, that absorbs carbon
dioxide when dry and releases it when exposed to moisture. We outline a particular implementation of such a moisture swing
and discuss the scale of the collectors, the energy consumption, and the indirect carbon dioxide emissions related to the
operation of carbon dioxide capture devices. 相似文献
67.
Katarzyna Kasperkiewicz Roman Major Anna Sypien Marcin Kot Marcin Dyner ukasz Major Adam Byrski Magdalena Kopernik Juergen M. Lackner 《Molecules (Basel, Switzerland)》2021,26(11)
The goal of the work was to develop materials dedicated to spine surgery that minimized the potential for infection originating from the transfer of bacteria during long surgeries. The bacteria form biofilms, causing implant loosening, pain and finally, a risk of paralysis for patients. Our strategy focused both on improvement of antibacterial properties against bacteria adhesion and on wear and corrosion resistance of tools for spine surgery. Further, a ~35% decrease in implant and tool dimensions was expected by introducing ultrahigh-strength titanium alloys for less-invasive surgeries. The tested materials, in the form of thin, multi-layered coatings, showed nanocrystalline microstructures. Performed direct-cytotoxicity studies (including lactate dehydrogenase activity measurement) showed that there was a low probability of adverse effects on surrounding SAOS-2 (Homo sapiens bone osteosarcoma) cells. The microbiological studies (e.g., ISO 22196 contact tests) showed that implanting Ag nanoparticles into Ti/TixN coatings inhibited the growth of E. coli and S. aureus cells and reduced their adhesion to the material surface. These findings suggest that Ag-nanoparticles present in implant coatings may potentially minimize infection risk and lower inherent stress. 相似文献
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