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排序方式: 共有271条查询结果,搜索用时 687 毫秒
111.
Dr. Soumen Dutta Dr. Nitee Kumari Dr. Sateesh Dubbu Sun Woo Jang Dr. Amit Kumar Dr. Hiroyoshi Ohtsu Junghoon Kim Prof. Seung Hwan Cho Prof. Masaki Kawano Prof. In Su Lee 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(9):3444-3450
Rational engineering and assimilation of diverse chemo- and biocatalytic functionalities in a single nanostructure is highly desired for efficient multistep chemical reactions but has so far remained elusive. Here, we design and synthesize multimodal catalytic nanoreactors (MCNRs) based on a mesoporous metal-organic framework (MOF). The MCNRs consist of customizable metal nanocrystals and stably anchored enzymes in the mesopores, as well as coordinatively unsaturated cationic metal MOF nodes, all within a single nanoreactor space. The highly intimate and diverse catalytic mesoporous microenvironments and facile accessibility to the active site in the MCNR enables the cooperative and synergistic participation from different chemo- and biocatalytic components. This was shown by one-pot multistep cascade reactions involving a heterogeneous catalytic nitroaldol reaction followed by a [Pd/lipase]-catalyzed chemoenzymatic dynamic kinetic resolution to yield optically pure (>99 % ee) nitroalcohol derivatives in quantitative yields. 相似文献
112.
A cholesterol-conjugated fluorescence Zn(2+) sensor based on the fluorescein platform was designed and synthesized. The cholesterol moiety is essential for localizing the Zn(2+) sensor to the cell membrane, allowing the sensor to probe changes in the Zn(2+) concentration in a localized area of the cell. 相似文献
113.
Noritaka Kuroda Yasuo Oeda Giyw Kido Masayasu Takeda Yuichiro Nishina Yasuaki Nakagawa 《高压研究》2013,33(1):65-66
Abstract The magneto-optical spectra of the R1 and R2 lines of Cr3+ ions in alexandrite have been measured under hydrostatic pressures and magnetic fields up to 6 GPa and 15 T, respectively. The spins of the excited states, 2E, have the Heisenberg-type characters at atmospheric pressure, though the g-values are anisotropic with the values between 1.3 and 2.0. The g-values for the direction parallel to the α-axis remain unchanged with increasing pressure, while for the directions normal to the α-axis they are reduced appreciably. The fine structure parameters of spins in the ground state, 4A2, exhibit quite a similar behavior. The R1-R2 splitting is reduced also by pressure. These properties are the evidences that the spins of the 2E states become of the king-type under pressures above about 15 GPa. The mechanism of such the change of spin character is discussed quantitatively on the basis of a crystal field model. 相似文献
114.
A gene encoding β-1,3-1,4-glucanase was cloned by polymerase chain reaction (PCR) from Bacillus subtilis MA139. Sequencing result showed 97% homology to the corresponding gene from Bacillus licheniformis. The open reading frame (ORF) of the gene contained 690 bp coding for a 226 amino-acid matured protein with the estimated
molecular weight of 24.44 kDa. The β-1,3-1,4-glucanase gene was subcloned into an expression vector of pET28a and expressed
in Escherichia coli BL21 and then purified by metal affinity chromatography using a nickel–nitrilotriacetic acid (Ni–NTA) column. The purified
β-1,3-1,4-glucanase demonstrated 24.05 and 12.52 U ml-1 activities for the substrates of barley β-glucan and lichenan, respectively, and the specific activities were 728.79 and
379.1 U mg-1 for them, respectively. The optimal temperature and pH of the purified enzyme were 40°C and 6.4, respectively. When barley
β-glucan was used as the substrate, K
m was 5.34 mg ml-1, and K
cat showed 7,206.71 S-1, thus the ratio of K
cat and K
m was 1,349.67 ml s-1 mg-1. The activity of β-1,3-1,4-glucanase was affected by a range of metal ions or ethylenediaminetetraacetic acid (EDTA). 相似文献
115.
116.
Osamu Araki Masayasu Horie Toshiro Masuda 《Journal of Polymer Science.Polymer Physics》2001,39(3):337-341
The physical aging of polycarbonate was investigated with dynamic viscoelastic measurements. Physical aging was observed for samples aged at 110 °C (QA) and room temperature (QP) after being quenched from the molten state. The shapes of the temperature dispersion curves of the dynamic viscoelastic functions (E′, E″, and tan δ) of the QA and QP samples changed with aging time in a temperature range below the glass‐transition temperature (Tg). However, at temperatures close to but below Tg, the curves for the aged samples merged into the curve of the quenched sample at a temperature denoted TH. TH increased with aging time. The experimental results suggest that the aged sample has a memory of having been quenched and that as the sample approaches the equilibrium state, this memory is lost. Differential scanning calorimetry thermograms showed an endothermic peak below Tg for the QA samples. The peak temperature (Tp) also increased with aging time. TH and Tp of the QA samples were approximately the same. The increase of both TH and Tp with aging time indicates that the structure of the polymeric chain in the glassy state relaxes over larger segment scale lengths because the scale of the movable segments is related to temperature. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 337–341, 2001 相似文献
117.
118.
Dr. Qian Wu Prof. Dr. Masayasu Taki Yoshiki Tanaka Dr. Manish Kesherwani Prof. Dr. Quan Manh Phung Dr. Sawako Enoki Prof. Dr. Yasushi Okada Prof. Dr. Florence Tama Prof. Dr. Shigehiro Yamaguchi 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2024,136(15):e202400711
The development of near-infrared (NIR) fluorophores that have both excellent chemical stability and photostability, as well as efficient cell permeability, is highly demanded. In this study, we present phospha-rhodamine (POR) dyes which display significantly improved performance for protein labeling. This is achieved by incorporating a 2-carboxy-3-benzothiophenyl group at the 9-position of the xanthene scaffold. The resulting cis and trans isomers were successfully isolated and structurally characterized using X-ray diffraction. The HaloTag ligand conjugates of the two isomers exhibited different staining abilities in live cells. While the cis isomer showed non-specific accumulation on the organelle membranes, the trans isomer selectively labeled the HaloTag-fused proteins, enabling the long-term imaging of cell division and the 5-color imaging of cell organelles. Molecular dynamics simulations of the HaloTag ligand conjugates within the lipid membrane suggested that the cis isomer is more prone to forming oligomers in the membrane. In contrast, the oligomerization of the trans isomer is effectively suppressed by its interaction with the lipid molecules. By taking advantage of the superior labeling performance of the trans isomer and its NIR-emissive properties, multi-color time-lapse super-resolution 3D imaging, namely super-resolution 5D-imaging, of the interconnected network between the endoplasmic reticulum and microtubules was achieved in living cells. 相似文献
119.