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251.
Frontispiece: New Insight into the Hydrocarbon‐Pool Chemistry of the Methanol‐to‐Olefins Conversion over Zeolite H‐ZSM‐5 from GC‐MS,Solid‐State NMR Spectroscopy,and DFT Calculations
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252.
An Unusual Dehydratase Acting on Glycerate and a Ketoreducatse Stereoselectively Reducing α‐Ketone in Polyketide Starter Unit Biosynthesis
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Dr. Hai‐Yan He Dr. Hua Yuan Dr. Man‐Cheng Tang Prof. Dr. Gong‐Li Tang 《Angewandte Chemie (International ed. in English)》2014,53(42):11315-11319
Polyketide synthases (PKSs) usually employ a ketoreductase (KR) to catalyze the reduction of a β‐keto group, followed by a dehydratase (DH) that drives the dehydration to form a double bond between the α‐ and β‐carbon atoms. Herein, a DH*‐KR* involved in FR901464 biosynthesis was characterized: DH* acts on glyceryl‐S‐acyl carrier protein (ACP) to yield ACP‐linked pyruvate; subsequently KR* reduces α‐ketone that yields L ‐lactyl‐S‐ACP as starter unit for polyketide biosynthesis. Genetic and biochemical evidence was found to support a similar pathway that is involved in the biosynthesis of lankacidins. These results not only identified new PKS domains acting on different substrates, but also provided additional options for engineering the PKS starter pathway or biocatalysis. 相似文献
253.
Chiral Metal–Organic Frameworks Bearing Free Carboxylic Acids for Organocatalyst Encapsulation
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Prof. Yan Liu Dr. Xiaobing Xi Chengcheng Ye Tengfei Gong Zhiwei Yang Prof. Yong Cui 《Angewandte Chemie (International ed. in English)》2014,53(50):13821-13825
Two chiral carboxylic acid functionalized micro‐ and mesoporous metal–organic frameworks (MOFs) are constructed by the stepwise assembly of triple‐stranded heptametallic helicates with six carboxylic acid groups. The mesoporous MOF with permanent porosity functions as a host for encapsulation of an enantiopure organic amine catalyst by combining carboxylic acids and chiral amines in situ through acid–base interactions. The organocatalyst‐loaded framework is shown to be an efficient and recyclable heterogeneous catalyst for the asymmetric direct aldol reactions with significantly enhanced stereoselectivity in relative to the homogeneous organocatalyst. 相似文献
254.
A rapid, simple and selective method based on molecularly imprinted, spin column extraction coupled with fluorescence detection was successfully established for the determination of 2,4-dinitrophenol in serum samples. The 2,4-dinitrophenol imprinted polymers exhibited highly selective recognition for the template molecule and the maximum adsorption capacity was 138.9 mg/g. The results indicated that when water is used as the loading solution, only 2,4-dinitrophenol could be adsorbed on the spin column without the remaining structural analogs(2-nitrophenol, 4-nitrophenol and phenol). After eluting with acetonitrile/acetic acid(9/1, v/v), 2,4-dinitrophenol in serum samples could be determined by using the fluorescence spectrometer, based on the fluorescence enhancement of fluorescein by the template molecule. Under the optimal conditions, the spiked recovery ranged from 95.8% to 103.4% and the detection limit was 1 nmol/L. The results confirmed the reliability and practicality of the protocol and revealed a good perspective of this method for biological sample analysis. 相似文献
255.
Yu-Cai He Lei Gong Feng Liu Ting Lu Qing Qing Li-Qun Wang Yue Zhang Feng-Ting Gao Xi Wang 《Applied biochemistry and biotechnology》2014,173(4):894-903
In the conversion of cassava starch dregs to biogas by anaerobic fermentation, the biogas residue (BR) containing lignocellulosic materials still remained in the environment. In order to effectively utilize BR, the complexed 1-methyl-3-methylimidazolium dimethyl phosphate ([Mmim]DMP) media were used for pretreating cellulosic materials. After the optimization of pretreatment, the IL [Mmim]DMP-HCl-water (78.5:1.5:20, w/w/w) pretreament media were used for pretreating BR at 130 °C for 30 min. Furthermore, BR pretreated could be effectively saccharified by cellulase of Galactomyces sp. CCZU11-1. Moreover, BR could be used as a cheap carbon source for the production of Galactomyces sp. CCZU11-1 cellulase. After the culture optimization, the optimal culture conditions were obtained as follows: BR 5 g/L, (NH4)2SO4 5 g/L, K2HPO4 2 g/L, MgSO4 0.2 g/L, NaCl 1 g/L, PEG6000 4 g/L, pH 5.5, and culture temperature 30 °C. After the fermentation for 6 days, the FPA and CMCase were 26.2 and 52.8 U/mL, respectively. In conclusion, waste BR could be chosen as a promising feedstock for biofuels. 相似文献
256.
Yanli Li Peiran Zhao Dr. Teng Gong Han Wang Dr. Xingwu Jiang Hui Cheng Dr. Yanyan Liu Dr. Yelin Wu Prof. Wenbo Bu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(50):22726-22732
Redox homeostasis is one of the main reasons for reactive oxygen species (ROS) tolerance in hypoxic tumors, limiting ROS-mediated tumor therapy. Proposed herein is a redox dyshomeostasis (RDH) strategy based on a nanoplatform, FeCysPW@ZIF-82@CAT Dz, to disrupt redox homeostasis, and its application to improve ROS-mediated hypoxic tumor therapy. Once endocytosed by tumor cells, the catalase DNAzyme (CAT Dz) loaded zeolitic imidazole framework-82 (ZIF-82@CAT Dz) shell can be degraded into Zn2+ as cofactors for CAT Dz mediated CAT silencing and electrophilic ligands for glutathione (GSH) depletion under hypoxia, both of which lead to intracellular RDH and H2O2 accumulation. These “disordered” cells show reduced resistance to ROS and are effectively killed by ferrous cysteine-phosphotungstate (FeCysPW) induced chemodynamic therapy (CDT). In vitro and in vivo data demonstrate that the pH/hypoxia/H2O2 triple stimuli responsive nanocomposite can efficiently kill hypoxic tumors. Overall, the RDH strategy provides a new way of thinking about ROS-mediated treatment of hypoxic tumors. 相似文献
257.
Light-Driven Crawling of Molecular Crystals by Phase-Dependent Transient Elastic Lattice Deformation
Yanjun Gong Yongxian Guo Fayuan Ge Wei Xiong Jie Su Yang Sun Chuang Zhang An-Min Cao Yifan Zhang Jincai Zhao Yanke Che 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(26):10423-10428
The light-driven crawling of a molecular crystal that can form three phases, (α, β, and γ) is presented. Laser irradiation of the molecular crystal can generate phase-dependent transient elastic lattice deformation. The resulting elastic lattice deformation that follows scanning irradiation of a laser can actuate the different phases of molecular crystal to move with different velocity and direction. Because the γ phase has a large Young's modulus (ca. 26 GPa), a force of 0.1 μN can be generated under one laser spot. The generated force is sufficient to actuate the γ-formed molecular crystals in a wide dimensional range to move longitudinally at a velocity of about 60 μm min−1, which is two orders of magnitude faster than the α and β phases. 相似文献
258.
Chaonan Mu Wei Wang Jie Wang Chu Gong Dongmei Zhang Prof. Dr. Xinxing Zhang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(48):21699-21703
While Type I and Type II photosensitizers are often carefully tailored to achieve their respective advantages in treating different cancers, the identifications of the Type I and II mechanisms as such, the key reaction intermediates, and the consequent oxidation products of the substrates have never been easy. Using our unique home-built field-induced droplet ionization mass spectrometry (FIDI-MS) method that selectively samples molecules at the air–water interface, here we show the facile determination of both Type I and II mechanisms of a poster-child photosensitizer, temoporfin, without the addition of any probes. The unstable doublet radical resulting from the hydrogen abstraction by the triplet temoporfin through the Type I mechanism is captured, manifesting the in situ advantage of FIDI-MS. We anticipate that the method developed in this study can be widely utilized in the future designs of novel photosensitizers and the screening of their photosensitization mechanisms. 相似文献
259.
Yang Lv Dr. Miaomiao Han Dr. Wanbing Gong Dongdong Wang Dr. Chun Chen Prof. Guozhong Wang Prof. Haimin Zhang Prof. Huijun Zhao 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(52):23727-23732
Selective hydrogenation of C=O against the conjugated C=C in cinnamaldehyde (CAL) is indispensable to produce cinnamyl alcohol (COL). Nonetheless, it is challenged by the low selectivity and the need to use organic solvents. Herein, for the first time, we report the use of Fe-Co alloy nanoparticles (NPs) on N-doped carbon support as a selective hydrogenation catalyst to efficiently convert CAL to COL. The resultant catalyst with the optimized Fe/Co ratio of 0.5 can achieve an exceptional COL selectivity of 91.7 % at a CAL conversion of 95.1 % in pure water medium under mild reaction conditions, ranking it the best performed catalyst reported to date. The experimental results confirm that the COL selectivity and CAL conversion efficiency are, respectively promoted by the presence of Fe and Co, while the synergism of the alloyed Fe-Co is the key to concurrently achieve high COL selectivity and CAL conversion efficiency. 相似文献