Reactive yet stable alkene reporters offer a facile route to studying fast biological processes via the cycloaddition-based bioorthogonal reactions. Here, we report the design and synthesis of a ...strained spirocyclic alkene, spiro2.3hex-1-ene (Sph), for an accelerated photoclick chemistry, and its site-specific introduction into proteins via amber codon suppression using the wild-type pyrrolysyl-tRNA synthetase/tRNACUA pair. Because of its high ring strain and reduced steric hindrance, Sph exhibited fast reaction kinetics (k 2 up to 34 000 M–1 s–1) in the photoclick chemistry and afforded rapid (<10 s) bioorthogonal protein labeling.
The objective of this paper was to investigate the hydrolysis and transepithelial transport of egg white peptides in Caco-2 cell monolayers and everted rat sacs. Results showed that egg white ...peptides had higher permeability but lower degradation in Caco-2 cell monolayers than found for everted rat sacs. Peptides LGAKDSTRT, DGSRQPVDN, VNDLQGKTS, and GKKDPVLKD were identified from not only the basolateral (BL) side of Caco-2 cell monolayers but also the serous side of everted rat sacs, suggesting that these four peptides could be transported intact in both model systems. In addition, there were 24 peptides identified from the apical (AP) side of Caco-2 cell monolayers and the mucosal side of everted rat sacs, indicating potential resistance to hydrolysis by brush border membrane peptidases. Among these, peptides IRDLLER, YAEERYP, and IRNVLQPS were demonstrated as having dipeptidyl peptidase IV (DPP-IV) inhibitory activities with IC50 values of 186.23 ± 15.25, 340.62 ± 4.73, and 598.28 ± 15.12 μM (P < 0.05), respectively. Furthermore, molecular docking revealed that the DPP-IV inhibitory peptides were predicted to form hydrogen-bonds, π–π bonds, and charge interactions with the activity sites, especially the amino acid residues located in the S2 pocket of DPP-IV, potentially contributing to their DPP-IV inhibitory activities.
We just click: Genetic incorporation of a cyclopropene amino acid CpK (see scheme) site‐specifically into proteins in E. coli and mammalian cells was achieved using an orthogonal aminoacyl‐tRNA ...synthetase/tRNACUA pair (CpKRS/MbtRNACUA). Cyclopropene exhibited fast reaction kinetics in the photoclick reaction and allowed rapid (ca. 2 min) labeling of proteins.
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•Peptides ADM and ADW were identified as bitter taste receptor blockers.•The IC50 values of peptides ADM and ADW were 420.32 μM and 403.29 μM, respectively.•THR86, ASP168 and PHE247 ...played key roles in the binding of ADM and ADW with T2R14.
Human bitter taste receptor TAS2R14 (T2R14) can widely perceive bitterness, which has always been an issue for people to overcome. This study was aimed at identifying bioactive peptides obtained from Oncorhynchus mykiss nebulin hydrolysates as bitter taste receptor blockers by physicochemical property prediction, molecular docking, and in vitro determination of bitterness intensity using electronic tongue. Exploration of the interaction mechanism of these peptides with T2R14 by molecular docking models indicated that peptides ADM and ADW had high affinities for T2R14 to block the binding of bitter substances into the receptor. Addition of ADM and ADW to quinine caused reduction in bitterness intensity, with IC50 values of 420.32 ± 6.26 μM and 403.29 ± 4.10 μM, respectively. Hydrogen bond interaction and hydrophobic interaction were responsible for manifesting the high affinities of these peptides for the receptor. Residues Thr86, Asp168, and Phe247 may be the key amino acids within the binding site.
In recent years, surface electromyography (sEMG)-based human-computer interaction has been developed to improve the quality of life for people. Gesture recognition based on the instantaneous values ...of sEMG has the advantages of accurate prediction and low latency. However, the low generalization ability of the hand gesture recognition method limits its application to new subjects and new hand gestures, and brings a heavy training burden. For this reason, based on a convolutional neural network, a transfer learning (TL) strategy for instantaneous gesture recognition is proposed to improve the generalization performance of the target network. CapgMyo and NinaPro DB1 are used to evaluate the validity of our proposed strategy. Compared with the non-transfer learning (non-TL) strategy, our proposed strategy improves the average accuracy of new subject and new gesture recognition by 18.7% and 8.74%, respectively, when up to three repeated gestures are employed. The TL strategy reduces the training time by a factor of three. Experiments verify the transferability of spatial features and the validity of the proposed strategy in improving the recognition accuracy of new subjects and new gestures, and reducing the training burden. The proposed TL strategy provides an effective way of improving the generalization ability of the gesture recognition system.
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•Three new ACE and DPP-IV inhibitory peptides were identified from egg.•IC50 values of ADF, MIR, and FGR against ACE were 27.75 mM, 24.97 mM and 66.98 μM.•IC50 values of ADF, MIR and ...FGR against DPP-IV were 16.83, 4.86 and 46.22 mM.
Angiotensin converting enzyme (ACE) and dipeptidyl peptidase IV (DPP-IV) are important membrane peptidases. The inhibition of ACE and DPP-IV enzymes has become a key therapeutic target for the treatment of hypertension and diabetes. This study was conducted to discover membrane peptidase inhibitory peptides that inhibit ACE and DPP-IV. Egg proteins were cleaved by pepsin and trypsin in silico. The potential activity, solubility, absorption, distribution, metabolism, excretion, and toxicity of the peptides were then predicted online. Finally, ACE and DPP-IV were applied as molecular docking targets for the potential peptides. After simulating gastrointestinal digestion, the IC50 values of ADF, MIR, and FGR against ACE activity were 27.75 ± 0.90 mM, 24.97 ± 0.80 mM, and 66.98 ± 1.40 μM, against DPP-IV activity were 16.83 mM, 4.86 mM, and 46.22 mM, respectively. The ACE and DPP-IV inhibitory peptides identified from hen egg proteins can be used as functional food ingredients for controlling hypertension and diabetes.
Photoactivatable fluorescent probes are invaluable tools for the study of biological processes with high resolution in space and time. Numerous strategies have been developed in generating ...photoactivatable fluorescent probes, most of which rely on the photo-“uncaging” and photoisomerization reactions. To broaden photoactivation modalities, here we report a new strategy in which the fluorophore is generated in situ through an intramolecular tetrazole-alkene cycloaddition reaction (“photoclick chemistry”). By conjugating a specific microtubule-binding taxoid core to the tetrazole/alkene prefluorophores, robust photoactivatable fluorescent probes were obtained with fast photoactivation (∼1 min) and high fluorescence turn-on ratio (up to 112-fold) in acetonitrile/PBS (1:1). Highly efficient photoactivation of the taxoid–tetrazoles inside the mammalian cells was also observed under a confocal fluorescence microscope when the treated cells were exposed to either a metal halide lamp light passing through a 300/395 filter or a 405 nm laser beam. Furthermore, a spatially controlled fluorescent labeling of microtubules in live CHO cells was demonstrated with a long-wavelength photoactivatable taxoid–tetrazole probe. Because of its modular design and tunability of the photoactivation efficiency and photophysical properties, this intramolecular photoclick reaction based approach should provide a versatile platform for designing photoactivatable fluorescent probes for various biological processes.
•RSEI’s spatial and temporal evolution in Lanxi urban agglomeration is analyzed.•GWR and Geodetector reveal key factors affecting RSEI.•Significant differences in the spatial distribution of RSEI in ...the Lanxi urban agglomeration.•RSEI has significantly improved in around 29.19 % of Lanxi urban agglomeration.•The influence of socio-economic factors is increasing.
An analysis of the spatiotemporal evolution of ecological quality and its driving factors in the Lanxi urban agglomeration is important for ensuring environmental protection and high-quality, sustainable development in the region. We used moderate resolution imaging spectroradiometer (MODIS) remote sensing images to construct a remote sensing ecological index (RSEI) using principal component analysis (PCA) to reflect the ecological quality of the Lanxi urban agglomeration. The spatial and temporal characteristics and future changes in the RSEI of the study area from 2000 to 2020 were explored using the Sen and Mann–Kendall test and Hurst index, and the effects of natural and human factors on spatial variation in the RSEI of the study area were analyzed using Geodetector and geographically weighted regression (GWR) models. There were three main results. (1) In the past 20 years, the annual average RSEI value in the Lanxi urban agglomeration has been increasing at a rate of 0.0057/a, and areas of unsatisfactory ecological environmental quality have been reduced. (2) The Hurst index indicates that the majority of the area (47.54 % of the study area) will probably experience a degradation trend in the future, with 19.98 % of the area improving and random changes occurring in 9.45 % of the study area. (3) Vegetation type, soil type, and precipitation were the main reasons for the spatial differentiation in RSEI, land use type was the main human influence, and the influence of socioeconomic factors such as population density and gross domestic product (GDP) increased significantly. Vegetation, soil, and land use types were positively correlated with RSEI. The research results are of great significance for promoting the construction of an ecological civilization and coordinating a balance between social development and ecological environmental protection.
Achieving an efficient and stable oxygen evolution reaction (OER) in an acidic or neutral medium is of paramount importance for hydrogen production via proton exchange membrane water electrolysis ...(PEM-WE). Supported iridium-based nanoparticles (NPs) are the state-of-the-art OER catalysts for PEM-WE, but the nonhomogeneous dispersion of these NPs on the support together with their nonuniform sizes usually leads to catalyst migration and agglomeration under strongly corrosive and oxidative OER conditions, eventually causing the loss of active surface area and/or catalytic species and thereby the degradation of OER performance. Here, we design a catalyst comprising surface atomic-step enriched ruthenium–iridium (RuIr) nanocrystals homogeneously dispersed on a metal organic framework (MOF) derived carbon support (RuIr@CoNC), which shows outstanding catalytic performance for OER with high mass activities of 2041, 970 and 205 A gRuIr –1 at an overpotential of 300 mV and can sustain continuous OER electrolysis up to 40, 45, and 90 h at 10 mA cm–2 with minimal degradation in 0.5 M H2SO4 (pH = 0.3), 0.05 M H2SO4 (pH = 1), and PBS (pH = 7.2) electrolytes, respectively. Comprehensive experimental studies and density functional theory (DFT) calculations reveal that the good performance of RuIr@CoNC can be attributed, on one hand, to the presence of abundant atomic steps that maximize the exposure of catalytically active sites and lower the limiting potential of the rate-determining step of OER and, on the other hand, to the strong interaction between RuIr nanocrystals and the CoNC support that endows homogeneous dispersion and firm immobilization of RuIr catalysts on CoNC. The RuIr@CoNC catalysts also show outstanding performance in a single-cell PEM electrolyzer, and their large-quantity synthesis is demonstrated.
![Design of Spiro[2.3]hex-1-e...](http://api.summon.serialssolutions.com/2.0.0/image/issn/XR4PS5YY4K/0002-7863/small "Design of Spiro[2.3]hex-1-ene, a Genetically Encodable Double-Strained Alkene for Superfast Photoclick Chemistry")
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