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1.
Minimalist photo-reactive probes, which consist of a photo-reactive group and a tag for detection of target proteins, are useful tools in chemical biology. Although several diazirine-based and aryl azide-based minimalist probes are available, no keto-based minimalist probe has yet been reported. Here we describe minimalist probes based on a 2-thienyl-substituted α-ketoamide bearing an alkyne group on the thiophene ring. The 3-alkyne probe showed the highest photo-affinity labeling efficiency.  相似文献   
2.
Abstract

The conformations of pyridinio-appended β-cyclodextrin (CDP+) and nicotinamide-appended β-cyclodextrin (CDNA+) were studied by NMR spectroscopy. The orientations of the pyridine residue of CDP+ and the nicotinamide residue of CDNA+ were determined by using a combination of NMR spectroscopic techniques. NMR spectra indicate that the shapes of the cavities of CDP+ and CDNA+ were changed after forming complexes. This change depended on the shape of the guest. CDNA+ could separate the 1H resonances at the Cβ position of racemic tryptophan into two sets of resonances for each enantiomer.  相似文献   
3.
Friedel-Crafts acylation of arenes with methylthio- (1) or phenylthio-acetyl chloride (2) provides ready access to α-methylthio- or α-phenylthio-substituted acetophenones. The acyl chlorides 1 and 2 reacted also with organoaluminum reagents to give α-sulfenylated alkanones.  相似文献   
4.
The elongation method with intermediate mechanical and electrostatic embedding (ELG-IMEE) is proposed. The electrostatic embedding uses atomic charges generated by a charge sensitivity analysis (CSA) method and parameterized for three different population analyses, namely, the Merz–Singh–Kollman scheme, the charge model 5, and the atomic polar tensor. The obtained CSA models were tested on two model systems. Test calculations show that the electrostatic embedding provides several times of decrease in the difference of energies of testing and reference calculations in comparison with the conventional elongation approach (ELG). The mechanical embedding is implemented in a combination of the conventional elongation method and the ONIOM approach. Moreover, it was demonstrated that the geometry optimization with the ELG-IMEE reduces the errors in the optimized structures by about one order in root-mean-square deviation, when compared to ELG.  相似文献   
5.
Histone deacetylases (HDACs) are key enzymatic regulators of many cellular processes such as gene expression, cell cycle, and tumorigenesis. These enzymes are attractive targets for drug development. However, very few simple methods for monitoring HDAC activity have been reported. Here, we have developed a fluorogenic probe, K4(Ac)-CCB, which consists of the histone H3 peptide containing acetyl-Lys and a coumarin fluorophore with a carbonate ester. By the simple addition of the probe to a HDAC solution, enzyme activity was clearly detected through spontaneous intramolecular transesterification, which renders the probe fluorescent. In addition, K4(Ac)-CCB can be applied to the evaluation of HDAC inhibitor activity. This is the first report to demonstrate the monitoring of HDAC activity by using a one-step procedure. Thus, our novel fluorogenic probe will provide a powerful tool for epigenetic research and the discovery of HDAC-targeted drugs.  相似文献   
6.
7.
A flow-type microreactor containing glutaminase-mesoporous silica composites with 10.6 nm pore diameter (TMPS10.6) was developed for the continuous synthesis of theanine, a unique amino acid. High enzymatic activity was exhibited by the local control of the reaction temperature.  相似文献   
8.
9.
We investigate frictional-drag reduction with electrolytic microbubbles based on image measurement of a turbulent flow in a water channel at Re = 4800 (based on the half channel height). Microbubbles with a diameter ranging 30–200 μm can reduce frictional drag by as much as 30% relative to single-phase flow even at low void fractions (α ≈ 3 × 10−4); however, drag reduction is only effective within a limited downstream distance from an electrode array. Arrangement of the optical system allows us to measure the bubble-production rate by water electrolysis from images near the wall and to trace the motion of bubbles. We also measure velocity fields using particle-tracking velocimetry based on a shallow depth-of-field approach by segregating tracer particles from microbubbles. Vertically oscillating microbubbles likely represent interaction with vortical structures near the wall, and bubbles approaching the wall appear to induce negative streamwise velocity relative to the surrounding fluid. We relate the wall friction with the double integral of the Reynolds-stress profile and show that its variation due to microbubbles decreases the drag on the wall. Microbubbles tend to coalesce downstream resulting in a fewer bubbles but with greater size; accordingly, the oscillatory motion diminishes, and the frictional drag rather increases.  相似文献   
10.
Small molecule labeling techniques for cellular proteins under physiological conditions are very promising for revealing new biological functions. We developed a no-wash fluorogenic labeling system by exploiting fluorescence resonance energy transfer (FRET)-based fluorescein-cephalosporin-azopyridinium probes and a mutant β-lactamase tag. Fast quencher elimination, hydrophilicity, and high resistance against autodegradation were achieved by rational refinement of the structure. By applying the probe to real-time pulse-chase analysis, the trafficking of epidermal growth factor receptors between cell surface and intracellular region was imaged. In addition, membrane-permeable derivatization of the probe enabled no-wash fluorogenic labeling of intracellular proteins.  相似文献   
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