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111.
HoSeok Park Prof. Dr. Young Mee Jung Prof. Dr. Seong Ho Yang Dr. Weonho Shin Jung Ku Kang Prof. Dr. Hoon Sik Kim Prof. Dr. Hyun Joo Lee Dr. Won Hi Hong Prof. Dr. 《Chemphyschem》2010,11(8):1711-1717
Geometric and conformational changes of zwitter‐type ionic liquids (ZILs) due to hydrogen‐bonding interactions with water molecules are investigated by density functional theory (DFT), two‐dimensional IR correlation spectroscopy (2D IR COS), and pulsed‐gradient spin‐echo NMR (PGSE NMR). Simulation results indicate that molecular structures in the optimized states are strongly influenced by hydrogen bonding of water molecules with the sulfonate group or imidazolium and pyrrolidinium rings of 3‐(1‐methyl‐3‐imidazolio)propanesulfonate ( 1 ) and 3‐(1‐methyl‐1‐pyrrolidinio)propanesulfonate ( 2 ), respectively. Concentration‐dependent 2D IR COS reveals kinetic conformational changes of the two ZIL–H2O systems attributable to intermolecular interactions, as well as the interactions of sulfonate groups and imidazolium or pyrrolidinium rings with water molecules. The dramatic changes in the 1H self‐diffusion coefficients elucidate the formation of proton‐conduction pathways consisting of ZIL networks. In ZIL domains, protons are transferred by a Grotthuss‐type mechanism through formation, breaking, and restructuring of bonds between ZILs and H2O, leading to an energetically favorable state. The simulation and experimental investigations delineated herein provide a perspective to understanding the interactions with water from an academic point of view as well as to designing ILs with desired properties from the viewpoint of applications. 相似文献
112.
Ganesh Shenoy Jessica Ettedgui Chandrasekhar Mushti Jennifer Hong Kelly Lane Burchelle Blackman Hak-Sung Jung Yasuharu Takagi Yeonee Seol Martin Brechbiel Rolf E. Swenson Keir C. Neuman 《Molecules (Basel, Switzerland)》2022,27(3)
Carboxylic acid is a commonly utilized functional group for covalent surface conjugation of carbon nanoparticles that is typically generated by acid oxidation. However, acid oxidation generates additional oxygen containing groups, including epoxides, ketones, aldehydes, lactones, and alcohols. We present a method to specifically enrich the carboxylic acid content on fluorescent nanodiamond (FND) surfaces. Lithium aluminum hydride is used to reduce oxygen containing surface groups to alcohols. The alcohols are then converted to carboxylic acids through a rhodium (II) acetate catalyzed carbene insertion reaction with tert–butyl diazoacetate and subsequent ester cleavage with trifluoroacetic acid. This carboxylic acid enrichment process significantly enhanced nanodiamond homogeneity and improved the efficiency of functionalizing the FND surface. Biotin functionalized fluorescent nanodiamonds were demonstrated to be robust and stable single-molecule fluorescence and optical trapping probes. 相似文献
113.
114.
Mg2Ru5B4 and Mg5Ru13B11, Two Ternary Magnesium Ruthenium Borides with Channel Structures The ternary borides Mg2Ru5B4 and Mg5Ru13B11, crystallizing in the orthorhombic space group Pbam, were prepared by reaction of the elementary components in sealed tantalum ampoules. Mg2Ru5B4 (a = 1000.0(2) pm, b = 837,6(1) pm, c = 295.42(3) pm, Z = 2, RW = 0.027 for 563 reflections) is homeotypic with Sc2Ru5B4. The structure contains BRu6-trigonal prisms, connected by faces and edges to form pentagonal channels filled with chains of magnesium atoms. Mg5Ru13B11 (a = 2190.1(2) pm, b = 996.7(2) pm, c = 294.65(3) pm, Z = 2, RW = 0.031 for 959 reflections) has a similar but so far unknown structure in which parts of the magnesium and boron atoms are disordered. 相似文献
115.
CHIP-mediated hyperubiquitylation of tau promotes its self-assembly into the insoluble tau filaments
Ji Hyeon Kim Jeeyoung Lee Won Hoon Choi Seoyoung Park Seo Hyeong Park Jung Hoon Lee Sang Min Lim Ji Young Mun Hyun-Soo Cho Dohyun Han Young Ho Suh Min Jae Lee 《Chemical science》2021,12(15):5599
The tau protein is a highly soluble and natively unfolded protein. Under pathological conditions, tau undergoes multiple post-translational modifications (PTMs) and conformational changes to form insoluble filaments, which are the proteinaceous signatures of tauopathies. To dissect the crosstalk among tau PTMs during the aggregation process, we phosphorylated and ubiquitylated recombinant tau in vitro using GSK3β and CHIP, respectively. The resulting phospho–ub-tau contained conventional polyubiquitin chains with lysine 48 linkages, sufficient for proteasomal degradation, whereas unphosphorylated ub-tau species retained only one–three ubiquitin moieties. Mass-spectrometric analysis of in vitro reconstituted phospho–ub-tau revealed seven additional ubiquitylation sites, some of which are known to stabilize tau protofilament stacking in the human brain with tauopathy. When the ubiquitylation reaction was prolonged, phospho–ub-tau transformed into insoluble hyperubiquitylated tau species featuring fibrillar morphology and in vitro seeding activity. We developed a small-molecule inhibitor of CHIP through biophysical screening; this effectively suppressed tau ubiquitylation in vitro and delayed its aggregation in cultured cells including primary cultured neurons. Our biochemical findings point to a “multiple-hit model,” where sequential events of tau phosphorylation and hyperubiquitylation function as a key driver of the fibrillization process, thus indicating that targeting tau ubiquitylation may be an effective strategy to alleviate the course of tauopathies.Multiple-hit model for tau aggregation, where sequential events of tau phosphorylation and hyperubiquitylation function as a key driver of the fibrillization process. 相似文献
116.
Ying-Ji Xin Soojung Choi Kyung-Baeg Roh Eunae Cho Hyanggi Ji Jin Bae Weon Deokhoon Park Wan Kyunn Whang Eunsun Jung 《Molecules (Basel, Switzerland)》2021,26(2)
Bidens pilosa L. (Asteraceae) has been used historically in traditional Asian medicine and is known to have a variety of biological effects. However, the specific active compounds responsible for the individual pharmacological effects of Bidens pilosa L. (B. pilosa) extract have not yet been made clear. This study aimed to investigate the anti-inflammatory phytochemicals obtained from B. pilosa. We isolated a flavonoids-type phytochemical, isookanin, from B. pilosa through bioassay-guided fractionation based on its capacity to inhibit inflammation. Some of isookanin’s biological properties have been reported; however, the anti-inflammatory mechanism of isookanin has not yet been studied. In the present study, we evaluated the anti-inflammatory activities of isookanin using lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages. We have shown that isookanin reduces the production of proinflammatory mediators (nitric oxide, prostaglandin E2) by inhibiting the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in LPS-stimulated macrophages. Isookanin also inhibited the expression of activator protein 1 (AP-1) and downregulated the LPS-induced phosphorylation of p38 mitogen-activated protein kinase (MAPK) and c-jun NH2-terminal kinase (JNK) in the MAPK signaling pathway. Additionally, isookanin inhibited proinflammatory cytokines (tumor necrosis factor-a (TNF-α), interleukin-6 (IL-6), interleukin-8 (IL-8), and interleukin-1β (IL-1β)) in LPS-induced THP-1 cells. These results demonstrate that isookanin could be a potential therapeutic candidate for inflammatory disease. 相似文献
117.
Pradip K. Bhowmik Tae S. Jo Jung J. Koh Jongwon Park Bidyut Biswas Ronald Carlo G. Principe Haesook Han Andrs F. Wacha Matti Knaapila 《Molecules (Basel, Switzerland)》2021,26(6)
A series of poly(pyridinium salt)s-fluorene main-chain ionic polymers with various organic counterions were synthesized by using ring-transmutation polymerization and metathesis reactions. Their chemical structures were characterized by Fourier Transform Infrared (FTIR), proton (1H), and fluorine 19 (19F) nuclear magnetic resonance (NMR) spectrometers. These polymers showed a number-average molecular weight (Mns) between 96.5 and 107.8 kg/mol and polydispersity index (PDI) in the range of 1.12–1.88. They exhibited fully-grown lyotropic phases in polar protic and aprotic solvents at different critical concentrations. Small-angle X-ray scattering for one polymer example indicates lyotropic structure formation for 60–80% solvent fraction. A lyotropic smectic phase contains 10 nm polymer platelets connected by tie molecules. The structure also incorporates a square packing motif within platelets. Thermal properties of polymers were affected by the size of counterions as determined by differential scanning calorimetry and thermogravimetric analysis measurements. Their ultraviolet-visible (UV-Vis) absorption spectra in different organic solvents were essentially identical, indicating that the closely spaced π-π* transitions occurred in their conjugated polymer structures. In contrast, the emission spectra of polymers exhibited a positive solvatochromism on changing the polarity of solvents. They emitted green lights in both polar and nonpolar organic solvents and showed blue light in the film-states, but their λem peaks were dependent on the size of the counterions. They formed aggregates in polar aprotic and protic solvents with the addition of water (v/v, 0–90%), and their λem peaks were blue shifted. 相似文献
118.
Thi Thanh Hanh Nguyen Jong-Hyun Jung Min-Kyu Kim Sangyong Lim Jae-Myoung Choi Byoungsang Chung Do-Won Kim Doman Kim 《Molecules (Basel, Switzerland)》2021,26(7)
The main protease (Mpro) is a major protease having an important role in viral replication of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the novel coronavirus that caused the pandemic of 2020. Here, active Mpro was obtained as a 34.5 kDa protein by overexpression in E. coli BL21 (DE3). The optimal pH and temperature of Mpro were 7.5 and 37 °C, respectively. Mpro displayed a Km value of 16 μM with Dabcyl-KTSAVLQ↓SGFRKME-Edans. Black garlic extract and 49 polyphenols were studied for their inhibitory effects on purified Mpro. The IC50 values were 137 μg/mL for black garlic extract and 9–197 μM for 15 polyphenols. The mixtures of tannic acid with puerarin, daidzein, and/or myricetin enhanced the inhibitory effects on Mpro. The structure–activity relationship of these polyphenols revealed that the hydroxyl group in C3′, C4′, C5′ in the B-ring, C3 in the C-ring, C7 in A-ring, the double bond between C2 and C3 in the C-ring, and glycosylation at C8 in the A-ring contributed to inhibitory effects of flavonoids on Mpro. 相似文献
119.
Kiho Lee Ji-Yoon Lee Kyeong Lee Cho-Rock Jung Min-Ju Kim Jung-Ah Kim Dong-Gu Yoo Eun-Jin Shin Soo-Jin Oh 《Molecules (Basel, Switzerland)》2021,26(7)
A novel HIF (hypoxia-inducible factor)-1α inhibitor, the (aryloxyacetylamino)benzoic acid derivative LW6, is an anticancer agent that inhibits the accumulation of HIF-1α. The aim of this study was to characterize and determine the structures of the metabolites of LW6 in ICR mice. Metabolite identification was performed using a predictive multiple reaction monitoring-information dependent acquisition-enhanced product ion (pMRM-IDA-EPI) method in negative ion mode on a hybrid triple quadrupole-linear ion trap mass spectrometer (QTRAP). A total of 12 metabolites were characterized based on their MS/MS spectra, and the retention times were compared with those of the parent compound. The metabolites were divided into five structural classes based on biotransformation reactions: amide hydrolysis, ester hydrolysis, mono-oxidation, glucuronidation, and a combination of these reactions. From this study, 2-(4-((3r,5r,7r)-adamantan-1-yl)phenoxy)acetic acid (APA, M7), the metabolite produced via amide hydrolysis, was found to be a major circulating metabolite of LW6 in mice. The results of this study can be used to improve the pharmacokinetic profile by lowering the clearance and increasing the exposure relative to LW6. 相似文献
120.
A series of “push-pull” porphyrins with 4-nitrophenyl and 4-aminophenyl substituents were synthesized and separated by flash column chromatographic techniques. They were fully characterized by elemental analysis, FAB-MS, FTIR, UV-visible, and 1H NMR spectroscopies. The unsymmetrical π-electron distribution of the porphyrins caused by the donor (amino) and acceptor (nitro) substituents were investigated by 1H NMR technique. The pyrrole-H resonance positions can be correlated to the Hammett σ constants of the substituents. Although with strong donor and acceptor substituents, UV-visible spectra show the push-pull porphyrins have rather weak solvatochromism and hence limited intramolecular charge-transfer character. 相似文献