The selective chemical modification of the 6-amino group of adenosine of the premature termination codon induces readthrough to produce full-length peptide in the reconstituted E. Coli translation system.

Nonsense mutations in the coding region turn amino acid codons into termination codons, resulting in premature termination codons (PTCs). In the case of the in-frame PTC, if translation does not stop at the PTC but continues to the natural termination codon (NTC) with the insertion of an amino acid, known as readthrough, the full-length peptide is formed, albeit with a single amino acid mutation. We have previously developed the functionality-transfer oligonucleotide (FT-Probe), which forms a hybrid complex with RNA of a complementary sequence to transfer the functional group, resulting in modification of the 4-amino group of cytosine or the 6-amino group of adenine. In this study, the FT-Probe was used to chemically modify the adenosines of the PTC (UAA, UAG, and UGA) of mRNA, which were assayed for the readthrough in a reconstituted Escherichia coli translation system. The third adenosine-modified UAA produced three readthrough peptides incorporating tyrosine, glutamine and lysine at the UAA site. It should be noted that the additional modification with a cyclodextrin only induced glutamine incorporation. The adenosine modified UGA induced readthrough very efficiently with selective tryptophan incorporation. Readthrough of the modified UGA is caused by inhibition of the RF2 function. This study has demonstrated that the chemical modification of the adenosine 6-amino group of the PTC is a strategy for effective readthrough in a prokaryotic translation system.

Acrolein Induces Changes in Cell Membrane and Cytosol Proteins of Erythrocytes.

High concentrations of acrolein (2-propenal) are found in polluted air and cigarette smoke, and may also be generated endogenously. Acrolein is also associated with the induction and progression of many diseases. The high reactivity of acrolein towards the thiol and amino groups of amino acids may cause damage to cell proteins. Acrolein may be responsible for the induction of oxidative stress in cells. We hypothesized that acrolein may contribute to the protein damage in erythrocytes, leading to the disruption of the structure of cell membranes. The lipid membrane fluidity, membrane cytoskeleton, and osmotic fragility were measured for erythrocytes incubated with acrolein for 24 h. The levels of thiol, amino, and carbonyl groups were determined in cell membrane and cytosol proteins. The level of non-enzymatic antioxidant potential (NEAC) and TBARS was also measured. The obtained research results showed that the exposure of erythrocytes to acrolein causes changes in the cell membrane and cytosol proteins. Acrolein stiffens the cell membrane of erythrocytes and increases their osmotic sensitivity. Moreover, it has been shown that erythrocytes treated with acrolein significantly reduce the non-enzymatic antioxidant potential of the cytosol compared to the control.

In Situ Reconstruction of Scalable Amorphous Indium-Based Metal-Organic Framework for CO2 Electroreduction to Formate over an Ultrawide Potential Window.

Amorphous metal-organic frameworks (aMOFs) are highly attractive for electrocatalytic applications due to their exceptional conductivity and abundant defect sites, but harsh preparation conditions of "top-down" strategy have hindered their widespread use. Herein, the scalable production of aMIL-68(In)-NH2 was successfully achieved through a facile "bottom-up" strategy involving ligand competition with 2-methylimidazole. Multiple in situ and ex situ characterizations reveal that aMIL-68(In)-NH2 evolutes into In/In2O3-x as the genuine active sites during the CO2 electrocatalytic reduction (CO2RR) process. Moreover, the retained amino groups could enhance the CO2 adsorption. As expected, the reconstructed catalyst demonstrates high formate Faradaic efficiency values (>90%) over a wide potential range of 800 mV in a flow cell, surpassing most top-ranking electrocatalysts. Density functional theory calculations reveal that the abundant oxygen vacancies in aMIL-68(In)-NH2 induce more local charges around electroactive sites, thereby promoting the formation of HCOO* intermediates. Furthermore, 16 g of samples can be readily prepared in one batch and exhibit almost identical CO2RR performances. This work offers a feasible batch-scale strategy to design amorphous MOFs for the highly efficient electrolytic CO2RR.

Bulk Trapping Organic Semiconductor with Amino-Additive Enabling Ultrasensitive NO2 Sensors.

Organic semiconductor (OSC) gas sensors have garnered considerable attention due to their promising selectivity and inherent flexibility. Introducing a functional group or modification layer is an important route to modulate the doping/trapping state of the active layer and the gas absorption/desorption process. However, the majority of the functionalization lies in the surface/interface assembling process, which is difficult to control the functional group density. This in turn brings challenges for precise modulation of the charge transport and the doping/trapping density, which will affect the repeatability and reproducibility of sensing performance. Herein, we propose a facile bulk trapping strategy incorporating amino-terminated additive molecules via the vacuum deposition process, achieving ultrahigh sensitivity of ∼2000%/ppm at room temperature to NO2 gas and approaching ∼3000%/ppm at 50 °C. Additionally, the device exhibits commendable reproducibility, stability, and low concentration detection ability, reaching down to several ppb, indicating promising potential for future applications. Comprehensive analysis of electrical properties and density functional theory calculations reveals that these exceptional properties arise from the favorable electrical characteristics of the bulk trapping structure, the high mobility of C8-BTBT, and the elevated adsorption energy of NO2. This approach enables the construction of stable and reproducible sensitive sensors and helps to understand the sensing mechanism in OSC gas sensors.

Amino-grafted Biochar as a Novel Photocatalyst for degradation of high concentration dye.

Photocatalytic degradation of organic pollution by biochar was a sustainable strategy for waste water remediation, nevertheless, it still suffers drawbacks like low efficiency due to the poor photocatalytic properties of pristine biochar. Herein, amino groups were grafted on the edge sites/defects of biochar by Friedel-Crafts acylation to enhance the degradation of high concentration dye solutions. The results suggested that the amino groups played an important role in imparting photocatalytic properties to biochar. Owing to the strong Lewis basicity and electron-donating ability of amino groups, their interaction with oxygen-containing functional groups/aromatic structures in biochar was improved, which enhanced the electron exchange ability of biochar under visible light irradiation, resulting in excellent degradation performances of high concentration RhB (∼10 times faster than ungrafted biochar). In this work, amino-grafted garlic peel biochar delivered a new idea for the future direction of biochar-based photocatalysis in wastewater remediation.

Lipase-Catalyzed Strategies for the Preparation of Enantiomeric THIQ and THßC Derivatives: Green Aspects.

This report reviews the most important lipase-catalyzed strategies for the preparation of pharmaceutically and chemically important tetrahydroisoquinoline and tetrahydro-ß-carboline enantiomers through O-acylation of the primary hydroxy group, N-acylation of the secondary amino group, and COOEt hydrolysis of the corresponding racemic compounds with simple molecular structure, which have been reported during the last decade. A brief introduction describes the importance and synthesis of tetrahydroisoquinoline and tetrahydro-ß-carboline derivatives, and it formulates the objectives of this compilation. The strategies are presented in chronological order, classified according to function of the reaction type, as kinetic and dynamic kinetic resolutions, in the main text. These reactions result in the desired products with excellent ee values. The pharmacological importance of the products together with their synthesis is given in the main text. The enzymatic hydrolysis of the hydrochloride salts as racemates of the starting amino carboxylic esters furnished the desired enantiomeric amino carboxylic acids quantitatively. The enzymatic reactions, performed in tBuOMe or H2O as usable solvents, and the transformations carried out in a continuous-flow system, indicate clear advantages, including atom economy, reproducibility, safer solvents, short reaction time, rapid heating and compression vs. shaker reactions. These features are highlighted in the main text.

Electrophysiological Assessment of Newly Synthesized 2,3-Benzodiazepine Derivatives for Inhibiting the AMPA Receptor Channel.

Three major subtypes of ionotropic receptors regulate glutamatergic synaptic transmission, one of which is α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptors (AMPARs). They are tetrameric, cation-permeable ionotropic glutamate receptors found across the brain. Abnormalities in AMPA receptor trafficking and synaptic assembly are linked to cognitive decline and neurological diseases such as Alzheimer's, Parkinson's, and Huntington's. The present study will investigate the effects of four novel 2,3-benzodiazepine derivatives on AMPA receptor subunits by comparing their effects on synaptic responses, desensitization, and deactivation rate in human embryonic kidney cells (HEK293T) recombinant AMPAR subunits using whole-cell patch-clamp electrophysiology. All four 2,3-BDZ compounds showed inhibitory activity against all the homomeric and heteromeric subunits tested. While the desensitization and deactivation rates in 2,3-BDZ-1 and 2,3-BDZ-2 decreased and increased, respectively, in the other two compounds (i.e., 2,3-BDZ-3 and 2,3-BDZ-4), there was no change in the desensitization or deactivation rates. These results contribute to a better understanding of AMPARs by identifying potential 2,3-BDZ drugs that demonstrate inhibitory effects on the AMPAR subunits.

Influence of the Solvent on the Stability of Aminopurine Tautomers and Properties of the Amino Group.

Amino derivatives of purine (2-, 6-, 8-, and N-NH2) have found many applications in biochemistry. This paper presents the results of a systematic computational study of the substituent and solvent effects in these systems. The issues considered are the electron-donating properties of NH2, its geometry, π-electron delocalization in purine rings and tautomeric stability. Calculations were performed in ten environments, with 1 < ε < 109, using the polarizable continuum model of solvation. Electron-donating properties were quantitatively described by cSAR (charge of the substituent active region) parameter and π-electron delocalization by using the HOMA (harmonic oscillator model of aromaticity) index. In aminopurines, NH2 proximity interactions depend on its position and the tautomer. The results show that they are the main factor determining how solvation affects the electron-donating strength and geometry of NH2. Proximity with the NH∙∙∙HN repulsive interaction between the NH2 and endocyclic NH group results in stronger solvent effects than the proximity with two attractive NH∙∙∙N interactions. The effect of amino and nitro (previously studied) substitution on aromaticity was compared; these two groups have, in most cases, the opposite effect, with the largest being in N1H and N3H purine tautomers. The amino group has a smaller effect on the tautomeric preferences of purine than the nitro group. Only in 8-aminopurine do tautomeric preferences change: N7H is more stable than N9H in H2O.

Hydrophilic Amino Groups Acted in the Hydrophobic Reaction Environment for Efficient Hydrogen Isotopes Enrichment.

Hydrogen isotope enrichment through liquid-phase catalytic exchange (LPCE) technology is achieved in a hydrophobic reaction environment to avoid liquid water poisoning, but the usage of hydrophobic support severely inhibits the internal diffusion of water molecules to decrease the catalytic efficiency. Herein, we encapsulate platinum active sites into a metal organic framework (Pt@NH2-UiO-66) as the efficient catalyst for LPCE via introducing hydrophilic amino groups. Experiments and density functional theory simulation reveal amino groups in the channel as the adsorption site of water molecules accelerates the internal diffusion and slows down the accumulation on the platinum sites. Meanwhile, the amino groups interact with the Pt site bridge electron transfer from active sites to support the host, thus decreasing the catalytic reaction and generated water desorption barrier. Due to these positive roles, the turnover frequency of Pt@NH2-UiO-66 reaches 2272 h-1 in a microchannel reactor. This work provides a novel design strategy of catalysts in LPCE.

Adsorption Characteristics for Cu(II) and Phosphate in Chitosan Beads under Single and Mixed Conditions.

Chitosan, a natural organic polymer, has shown bifunctional characteristics in the removal of cationic and anionic contaminants from water and wastewater treatment. In particular, cationic Cu(II) and anionic phosphate can simultaneously interact with chitosan owing to the presence of the amino group in the form of NH2 and NH3+ in chitosan. To gain greater insight into the bifunctional adsorption characteristics of chitosan, its adsorption capacity for Cu(II) and phosphate was tested under single and mixed (co-ion) conditions to investigate the interactions between four types of chitosan beads and NH2 and NH3+. In the single condition, Cu(II) uptake was reduced from 0.243 to 0.0197 mmol/g due to the crosslinking and drying processes, whereas no significant reduction in phosphate uptake was observed, indicating that the crosslinking agent only interacted with NH2 to decrease the number of available adsorption sites for Cu(II). Under the mixed condition, the simultaneous presence of the two ions clearly increased the uptake of each other, with the adsorption of phosphate being more influenced than that of Cu(II). The comparison of the rate constant, k1 or k2, using pseudo-first- and pseudo-second-order models confirmed that phosphate reached equilibrium faster than Cu(II), suggesting that electrostatic interaction was preferred over coordination. In addition, under mixed conditions, co-ion competition slowed down the adsorption kinetics for both Cu(II) and phosphate.

Ultrasensitive Small-Molecule Fluorescent Thermometer Reveals Hot Mitochondria in Surgically Resected Human Tumors.

The Warburg effect suggests that upregulated glycolysis arising from high glucose uptake in cancer cells might be accompanied with suppressed mitochondrial respiration. However, recent studies have shown that the mitochondrial temperature in cancer cells could be relatively higher than that in normal cells, suggesting hyperactive mitochondrial respiration in cancer cells. However, hot mitochondria have not been reported in patients with cancer. Here, near-infrared small-molecule fluorescent probes TRNs are rationally designed with two ethyl amino groups as the temperature-sensitive moiety. Afterward, a mitochondrial targeting group is installed via ether bonds on TRN-8 to build MTN. To the best of our knowledge, MTN is the near-infrared probe with the highest sensitivity for mitochondrial temperature. Moreover, it also displays high photostability, wide linearity, and high specificity. Using MTN, we can monitor the ups and downs of mitochondrial temperature in cancer cells upon the perturbations of mitochondrial respiration. Furthermore, we demonstrate that the mitochondrial temperature in surgically resected human tumors is relatively higher than that in paracancerous tissues. Our results indicate that relatively hot mitochondria may exist in tumors from patients. We envisage that our study provides critical evidence for revisiting the Warburg effect and cancer metabolism.

Crystal structure, Hirshfeld surface analysis, inter-molecular inter-action energies, energy frameworks and DFT calculations of 4-amino-1-(prop-2-yn-1-yl)pyrimidin-2(1H)-one.

In the title mol-ecule, C7H7N3O, the pyrimidine ring is essentially planar, with the propynyl group rotated out of this plane by 15.31 (4)°. In the crystal, a tri-periodic network is formed by N-H⋯O, N-H⋯N and C-H⋯O hydrogen-bonding and slipped π-π stacking inter-actions, leading to narrow channels extending parallel to the c axis. Hirshfeld surface analysis of the crystal structure reveals that the most important contributions for the crystal packing are from H⋯H (36.2%), H⋯C/C⋯H (20.9%), H⋯O/O⋯H (17.8%) and H⋯N/N⋯H (12.2%) inter-actions, showing that hydrogen-bonding and van der Waals inter-actions are the dominant inter-actions in the crystal packing. Evaluation of the electrostatic, dispersion and total energy frameworks indicates that the stabilization is dominated by the electrostatic energy contributions. The mol-ecular structure optimized by density functional theory (DFT) calculations at the B3LYP/6-311 G(d,p) level is compared with the experimentally determined structure in the solid state. The HOMO-LUMO behaviour was also elucidated to determine the energy gap.

Intramolecular Interactions in Derivatives of Uracil Tautomers.

The influence of solvents on intramolecular interactions in 5- or 6-substituted nitro and amino derivatives of six tautomeric forms of uracil was investigated. For this purpose, the density functional theory (B97-D3/aug-cc-pVDZ) calculations were performed in ten environments (1 > ε > 109) using the polarizable continuum model (PCM) of solvation. The substituents were characterized by electronic (charge of the substituent active region, cSAR) and geometric parameters. Intramolecular interactions between non-covalently bonded atoms were investigated using the theory of atoms in molecules (AIM) and the non-covalent interaction index (NCI) method, which allowed discussion of possible interactions between the substituents and N/NH endocyclic as well as =O/−OH exocyclic groups. The nitro group was more electron-withdrawing in the 5 than in the 6 position, while the opposite effect was observed in the case of electron donation of the amino group. These properties of both groups were enhanced in polar solvents; the enhancement depended on the ortho interactions. Substitution or solvation did not change tautomeric preferences of uracil significantly. However, the formation of a strong NO∙∙∙HO intramolecular hydrogen bond in the 5-NO2 derivative stabilized the dienol tautomer from +17.9 (unsubstituted) to +5.4 kcal/mol (substituted, energy relative to the most stable diketo tautomer).

Enhancing the Alkaline Hydrogen Evolution Reaction of Graphene Quantum Dots by Ethylenediamine Functionalization.

Developing metal-free photocatalyst for water splitting is one of the important rising research topics. Although graphene quantum dots (GQDs) have already been investigated as a water splitting photocatalyst several times, studies on modification and design are still needed for an efficient hydrogen evolution reaction (HER) rate particularly in alkaline solutions with an aim to realize overall water splitting. We have synthesized covalently functionalized GQDs with ethylenediamine (EDA) by an amide coupling reaction. It was found that EDA-functionalized GQDs generally exhibited much higher HER activity than bare GQDs. Importantly, the HER activity of EDA-functionalized GQDs increased in proportion to the pH and peaked at pH = 10, which is in stark contrast to the simple decreasing HER rate with the pH of bare GQDs. Through linear sweep voltammetry measurement and electrochemical impedance spectroscopy analysis, it was verified that covalently bonded EDA acts as water dissociation sites to enhance the photocatalytic HER in alkaline medium.

Synthesis of a cyclic tetramer of 3-amino-3-deoxyallose with axially oriented amino groups.

A linear tetramer of ß-(1 â†’ 6)-linked 3-azido-3-deoxy-d-allose containing glycosyl donor and glycosyl acceptor functions in the terminal monosaccharide units was prepared starting from 3-azido-3-deoxy-1,2:5,6-di-O-isopropylidene-α-d-allofuranose. Cyclization of the linear tetramer under glycosylation conditions afforded the corresponding cyclic tetrasaccharide in 77% yield; its deprotection and reduction of the azido groups resulted in the formation of the cyclic tetramer of 3-amino-3-deoxy-d-allose with axial amino groups, a potential scaffold for the synthesis of tetravalent functional clusters.

pH-Induced Electrostatic Interaction between Polyacrylates and Amino-Functionalized Graphene Oxide on Stability and Coating Performances.

Electrostatic interaction between polymers and nanofillers is of great importance for the properties and design of their composites. Polyacrylates with carboxyl, hydroxyl and acylamino groups were synthesized via emulsion polymerization and marked as P(MMA-BA-AA), P(MMA-BA-HEA) and P(MMA-BA-AM), respectively. Amino-functionalized graphene oxide (NGO) was prepared by Hoffman rearrangement using GO as the raw material. The polyacrylate composites were prepared by mixing NGO with each of the three kinds of polyacrylate. Effects of pH and NGO amounts on the properties of polyacrylate composites were studied. It was found that the surface charge of polyacrylate and NGO had the greatest effect on the composite properties. P(MMA-BA-AM)/NGO was not stable at any pH (2-8). With the same NGO amount of 0.1 wt%, the toughening effect of NGO on P(MMA-BA-AA) was larger than that on P(MMA-BA-HEA). The break strength of P(MMA-BA-AA)/NGO and P(MMA-BA-HEA)/NGO increased to 5.22 MPa by 47% and 3.08 MPa by 31%, respectively. NGO could increase the thermal stability of P(MMA-BA-AA) and P(MMA-BA-HEA) to different degrees. The polyacrylate film-forming processes were tested, and it showed that NGO influenced polyacrylate through the whole film-forming process. The results provide potential methods for the design of polymer-based nanocomposites.

Lignans with (N, N-diethyl)methyl amino group from Buxus rugulosa.

Buxrugulosides A-E, four lignan glycosides (1-4) and a protocatechuate derivative (5) featuring a rare (N, N-diethyl)methyl amino group at aromatic rings, were obtained from the aerial parts of Buxus rugulosa, which is famous for treating coronary heart disease. Their structures including absolute configurations were elucidated by HRMS, 1D and 2D NMR, and by comparing their CD data with previous reports. Compound 1 was a rare sesquilignan, and all of these compounds were the first example of lignans with (N, N-diethyl)methyl amino group.

Nitrogen Functionalities of Amino-Functionalized Nitrogen-Doped Graphene Quantum Dots for Highly Efficient Enhancement of Antimicrobial Therapy to Eliminate Methicillin-Resistant Staphylococcus aureus and Utilization as a Contrast Agent.

There is an urgent need for materials that can efficiently generate reactive oxygen species (ROS) and be used in photodynamic therapy (PDT) as two-photon imaging contrast probes. In this study, graphene quantum dots (GQDs) were subjected to amino group functionalization and nitrogen doping (amino-N-GQDs) via annealing and hydrothermal ammonia autoclave treatments. The synthesized dots could serve as a photosensitizer in PDT and generate more ROS than conventional GQDs under 60-s low-energy (fixed output power: 0.07 W·cm-2) excitation exerted by a 670-nm continuous-wave laser. The generated ROS were used to completely eliminate a multidrug-resistant strain of methicillin-resistant Staphylococcus aureus (MRSA), a Gram-positive bacterium. Compared with conventional GQDs, the amino-N-GQDs had superior optical properties, including stronger absorption, higher quantum yield (0.34), stronger luminescence, and high stability under exposure. The high photostability and intrinsic luminescence of amino-N-GQDs contribute to their suitability as contrast probes for use in biomedical imaging, in addition to their bacteria tracking and localization abilities. Herein, the dual-modality amino-N-GQDs in PDT easily eliminated multidrug-resistant bacteria, ultimately revealing their potential for use in future clinical applications.

Cu(II) and Cd(II) removal from aqueous solution with LDH@GO-NH2 and LDH@GO-SH: kinetics and probable mechanism.

Two novel adsorbents (LDH@GO-NH2 and LDH@GO-SH) were successfully synthesized by grafting thiol- or amino-functionalized GO onto LDH and their adsorption capacities for heavy metal ions (Cu(II) and Cd(II)) were significantly enhanced. Characterization experiments illustrated that the thiol group (-SH) or amino group (-NH2) was grafted onto LDH@GO-NH2 or LDH@GO-SH. Adsorption isotherms were satisfactorily fitted by both Langmuir and Freundlich models. The maximum adsorption capacity of Cd(II) on LDH@GO-SH at 308 K was 102.77 mg/g, which was about triple that of LDH@GO-NH2. The enhancement in adsorption capacity of LDH@GO-SH was due to the cooperative effect of LDH and GO-SH. The kinetic experimental data for LDH@GO-NH2 and LDH@GO-SH were found to be in good agreement with the pseudo-second-order model. The thermodynamic parameters calculated from the temperature-dependent adsorption isotherms indicated that the adsorption was spontaneous and an endothermic process. The possible adsorption mechanisms comprising formation of precipitation, isomorphic substitution of Mg(II), and formation of complexation with amino groups or thiol groups were proposed. Desorption experiments put into evidence that LDH@GO-NH2 and LDH@GO-SH may be promising suitable candidates for the remediation of metal ions from aqueous solutions in real work in the near future.

Removal of p-arsanilic acid and phenylarsonic acid from water by Fenton coagulation process: influence of substituted amino group.

Phenylarsonic acid compounds, which were widely used in poultry and swine production, are often introduced to agricultural soils with animal wastes. Fenton coagulation process is thought as an efficient method to remove them. However, the substituted amino group could apparently influence the removal efficiency in Fenton coagulation process. Herein, we investigated the optimal conditions to treat typical organoarsenic contaminants (p-arsanilic acid (p-ASA) and phenylarsonic acid (PAA)) in aqueous solution based on Fenton coagulation process for oxidizing them and capturing the released inorganic arsenic, and elucidated the influence mechanism of substituted amino group on removal. Results showed that the pH value and the dosage of H2O2 and Fe2+ significantly influenced the performance of the oxidation and coagulation processes. The optimal conditions for removing 20 mg L-1-As in this research were 40mg L-1 Fe2+ and 60mg L-1 H2O2 (the mass ratio of Fe2+/H2O2 = 1.5), initial solution pH of 3.0, and final solution pH of 5.0 adjusting after 30-min Fenton oxidation reaction. Meanwhile, the substituted amino group made p-ASA much more easily be attacked by ·OH than PAA and supply one more binding sites for forming complexes with Fe3+ hydrolysates, resulting in 36% higher oxidation rate and 7% better coagulation performance at the optimal conditions.