Acetate Molecules Research Articles

Improving Solubility and Avoiding Hygroscopicity of Tetrahydropalmatine by Forming a Pharmaceutical Salt Cocrystal via CAHBs

AbstractIn order to improve the solubility of tetrahydropalmatine (THP), an unreported THP‐sulfosalicylic acid (THP‐SSA) pharmaceutical salt cocrystal is designed and synthesized. Structural analysis shows that the building unit of THP‐SSA is composed of two THP cations, two SSA anions and one ethyl acetate molecule. Meanwhile, 1D chain, 2D layered structure, 3D hydrogen bond network, and Supramolecular motif R1110(48) of THP‐SSA are connected by stable charge‐assisted hydrogen bonds (CAHBs) N+‐H···O‐, π–π packing, and hydrogen bond. As expected, the maximum solubility of THP‐SSA in water is about 60 times that of THP, probably due to the protonation of the N atom on the piperidine ring in THP forms a pharmaceutical salt cocrystal, which greatly improves the solubility of THP. However, to the surprise, the hygroscopicity of THP‐SSA is also effectively reduced compared with THP, probably because the hydrogen bonds between THP and SSA have been formed, preventing the entry of water molecules. In addition, THP‐SSA also has higher antibacterial activity than THP. This suggests that forming a pharmaceutical salt cocrystal by cocrystal technology can not only improve the solubility of THP and avoid the hygroscopic property, but also improve the antibacterial activity of THP in vitro.

Approaches on Improving Electroreduction of Carbon Monoxide to Acetate in Flow Electrolyzer

Acetic acid (CH3COOH) is an important industrial chemical that is widely used in the generation of various products including medicals, food, solvent, synthetic fibers and fabrics. Although most acetic acid production today relies on the carbonylation process of methanol1, electrochemical synthesis method is a promising direction owing to its uniqueness in ambient conditions, utilization of renewable energy, and compatibility with bioengineering2. Cupper has the capability to electrochemically reduce CO2 to various C2 products but with low selectivity. The critical steps for acetate molecule generation from CO2/CO are the CO-dimerization and the nucleophilic attack of hydroxide ion on a ketene intermediate3, in which acetate production could be enhanced by electroreducing CO in alkaline electrolyte as compared to CO2 electroreduction in pH neutral solution. Meanwhile, the use of flow electrolyzer further improved the gas transport process by employing gas diffusion electrode, boosting the current and yield rate of products to industrial level. However, electrochemical reduction of CO to acetate on Cu-based electrocatalysts still suffers from low faradaic efficiency (<50%).4 In this talk, we will present our recent work on CO electroreduction to acetate by commercial Cu catalyst in flow electrolyzer. Parameters in terms of electrolyte molarity, catalyst loading, catalyst deposition method, and ionomer were manipulated to maximize the acetate production. Acetate was favored in high pH electrolyte by facilitating the nucleophilic attack of hydroxide ion process and suppressing competing proton transfer process towards ethylene and ethanol. Catalyst loading on gas diffusion electrode had great influence on the products selectivity, where low catalyst loading leans to ethylene generation, intermediate catalyst loading is selective to produce acetate, and high catalyst loading improves alcohol yield. A record 68% faradaic efficiency of acetate from CO with partial current density of 102 mA/cm2 was reached. Reference A. Dimian and A. Kiss, Chem. Eng. Res. Des., 159 (2020).S. Guo, T. Asset, and P. Atanassov, ACS Catal., 5172–5188 (2021) https://pubs.acs.org/doi/abs/10.1021/acscatal.0c04862.M. Jouny et al., Nat. Chem., 11, 846–851 (2019) https://doi.org/10.1038/s41557-019-0312-z.W. Luc et al., Nat. Catal., 2, 423–430 (2019) https://doi.org/10.1038/s41929-019-0269-8. Figure 1

An acetate-independent pathway for isopropanol production via HMG-CoA in Escherichia coli

Isopropanol has a good potential as a new fuel substitution. In the model biosynthesis pathway of isopropanol synthesis, acetoacetyl-CoA is converted to acetoacetate by acetoacetyl-CoA transferases, which requires an acetate molecule as a substrate. Herein, a novel isopropanol synthesis pathway based on mammalian ketone metabolic pathway was developed. In this pathway, acetoacetyl-CoA is condensed with acetyl-CoA to generate 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) by HMG-CoA synthase, and then catalyzed by HMG-CoA lyase to generate acetoacetate. This process is acetate-independent. Under the same experimental system using glycerol as carbon source, the E. coli strain MG::ISOP1 containing the novel pathway produced 11.7 times more isopropanol than the strain MG::ISOP0 containing the model pathway. The pta-ackA knockout mutant strain MG∆pta-ackA::ISOP1, which reduced the conversion of acetyl-CoA to acetate, further increased the production from 76 mg/L to 360 mg/L. In another strategy, knocking out atoDA to block the acetoacetate degradation pathway in strain MG∆atoDA::ISOP1 increased the production to 680 mg/L. By knocking out both of pta-ackA and atoDA, strain MGΔpta-ackAΔatoDA::ISOP1 produced 964 mg/L of isopropanol, which was 12.7 times that of MG::ISOP1. This study indicated that the novel pathway is competent for isopropanol synthesis, and provides a new perspective for biosynthesis of isopropanol.

2′,7′-Dichlorofluorescein: Biological, Analytical, and Industrial Progress

Abstrack: Fluorescein derivatives have attracted a great deal of attention for ubiquitous applications on account of their unique properties. Particularly, the 2′,7′-dichlorofluorescein (DCF) is of paramount importance in biological, analytical, and industrial fields. Mainly, DCF has been employed as a reactant in reactive oxygen species (ROS) formation reactions in biological applications. It has been utilized in oxidative stress and cell spreading measurement. It has been extensively explored to analyze oxidative, respiratory burst, secretory peroxidase, and multidrug resistance-associated proteins (MRPs). It has been widely investigated for detecting/quantification of H2O2, glucose, lipid, cholesterol, other hydroperoxides, and polycationic protamine. Moreover, it has been applied to differentiate dopamine from ascorbic acid. It has also shown immense potential in biolabeling, cancer imaging, and drug delivery. Several studies demonstrated the great promise of DCF as a fluorescent probe for real-time monitoring/quantification of mercury, cadmium, zinc, arsenite, acetate, fluoride, thiocyanate, azide ions, hydrogen peroxide, ammonia, ozone, sulfur dioxide, and drug molecules. Furthermore, the use of DCF to manufacture dyesensitized solar cells and Schottky barrier devices opens up avenues for its industrial applications. Apart from presenting a comprehensive account of the immense potential of DCF in the areas mentioned above, the present review also intends to provide insight into its broader future scope for a myriad of applications to emerge.

δ-antimonene nanosheet as a sensing element for ethyl acetate and butyl acetate – a first-principles study

The detection of volatile organic compounds, such as ethyl acetate, and butyl acetate emitted from industries is essential to ensure safety. The two-dimensional (2D) material δ-antimonene nanosheet (δ-SbNS) is used as a base substrate for the detection of ethyl acetate, and butyl acetate vapours. Based on the first-principles investigation, the structural stability and electronic properties of δ-SbNS are determined. The adsorption energy indicates that ethyl acetate and butyl acetate molecules are physisorbed on δ-SbNS. Furthermore, the electron difference density and charge transfer studies reveal the acceptor nature of δ-SbNS. Also, the projected density of states (PDOS) and energy band structure studies upon adsorption of ethyl acetate, and butyl acetate on δ-SbNS are reported. The δ-SbNS behaves as a chemi-resistor owing to adsorption and desorption of ethyl acetate, and butyl acetate vapours.

Sensing response of novel ε-antimonene nanosheet towards ethyl acetate and isopropyl acetate – A DFT insight

We deployed ε-antimonene nanosheet (ε-SbNS) as a chemical sensor to sense ethyl acetate (EA) and isopropyl acetate (IPA) molecules at ambient conditions. At first, the structural firmness of ε-SbNS is validated with the support of formation energy, phonon band spectrum, and elastic constants. Further, the electronic properties of the ε-SbNS are conversed using the projected density of states (PDOS) and band structure. The band gap value of ε-SbNS is calculated to be 0.461 eV. Importantly, the adsorption behaviour of chief EA and IPA molecules is studied by determining parameters Bader charge transfer, adsorption energy, and relative energy gap variation. The range of adsorption energy (−0.026 eV to −0.283 eV) reveals that the EA and IPA are physisorbed on ε-SbNS. The findings suggested that ε-SbNS can be employed as a chemical sensor to detect the acetate ester molecules emitted from paint and varnish industries.

Crystal structure of fulvestrant hydrate (ethyl acetate), C32H47F5O3S(H2O)0.16(C4H8O2)0.025

The crystal structure of fulvestrant hydrate (ethyl acetate) has been solved and refined using synchrotron X-ray powder diffraction data, and optimized using density functional theory techniques. This solvate of fulvestrant crystallizes in space group R3 (#146) with a = 23.39188(16), c = 16.50885(13) Å, V = 7823.08(7) Å3, and Z = 9. The crystal structure is composed of triangular hydrogen-bonded chains of molecules around one of the threefold axes. The fluorinated ends of the molecules cluster around another threefold axis. Voids around a threefold axis occupy 8.1% of the unit cell volume, and are partially occupied by the water and ethyl acetate molecules. Both hydroxyl groups act as donors in O–H⋯O hydrogen bonds. These H-bonds form a large ring. The powder pattern has been submitted to ICDD® for inclusion in the Powder Diffraction File™ (PDF®).

Morphological and chemical evolution of transient interfaces during zinc oxide cold sintering process

Although zinc oxide has a high melting point of 1975 °C, the recent development of the cold sintering process has shown that highly dense polycrystalline ceramics can be obtained at 150 °C or below. As such unusual densification does not yet have fully elucidated underlying mechanisms, this study aims to provide a comprehensive investigation of transient morphological and chemical interfaces during isothermal dwell. The chemical “transient” interface involves the formation of a zinc carboxylate complex by reacting the host zinc oxide powder and acetic acid solution, which is later consumed for the recrystallization on the lattice of an adjacent grain with a decomposition of the complex. Hence, the final outcome can be a residual-free zinc oxide phase. Regarding the morphological evolution, gas physisorption studies were conducted to quantify the area of solid–vapor interfaces and the Schlaffer model was used to analyze the activation energy for specific surface area reduction. Moreover, transmission electron micrographs revealed that the recrystallization occurs at the interface between crystalline grain and carbon-rich amorphous phase. After 30 minutes of isothermal dwell, the area of the amorphous phase was significantly decreased while grain size was increased, potentially indicating the recrystallization-induced grain growth and pore closure. The chemical transition at the zinc oxide surface was further investigated using ReaxFF molecular dynamics simulation, observing that acetate molecule acts as a bridging complex to connect zinc ions to the surface. Overall, understanding the evolution of the transient interface is a crucial subject to obtaining a residual-free cold-sintered sample with desired grain size and properties for application developments.

Space-confined growth of 2D MOF sheets between GO layers at room temperature for superior PDMS membrane-based ester/water separation

Expanding the metal–organic frameworks (MOFs) category using room-temperature colloidal chemistry route with regular crystal structure is challenging, but important for reducing energy consumption and realizing an economically viable application in industry. Herein, we developed a novel advanced copper terephthalate MOF (CuBDC) between graphene oxide (GO) layers using a simple space-confined growth strategy at room temperature. The inclusion of CuBDC@GO can realize high filler loadings while maintaining uniform dispersion throughout PDMS matrix. The paralled arranged CuBDC sheets created 1D inner vertical channels, along with the enlarged GO interlayer space for rapid molecule permeselective transport. The resultant mixed matrix membranes (MMMs) with 30 wt% CuBDC@GO loading improved the separation factor from 190.6 to 576.3, and simultaneously increased the total flux from 575.2 to 1357.4 g m-2 h-1 for separating 0.5 wt% butyl acetate at 40 °C. The transport mechanism was explained by adjusting the CuBDC content in composites to examine the significant increase in membrane permeability (from 12.5 to 58.3) and selectivity (from 0.7 to 2.0). Compared to alcohol or ketone, the larger size strip-like butyl acetate molecules are ideal for rapid transport through the CuBDC-supported 1D continuous inner channels, and effectively inhibit the movement of water molecules, ultimately resulting in the largest pervaporation performance improvement in butyl acetate/water separation. This CuBDC@GO prepared by a simple, green and room-temperature synthesis route can be widely applied to prepare defect-free membranes with excellent performance for sustainable applications. We also anticipate that this advanced space-confined growth strategy can be extended to various other MOFs and applications.

Protecting ice from melting under sunlight via radiative cooling.

As ice plays a critical role in various aspects of life, from food preservation to ice sports and ecosystem, it is desirable to protect ice from melting, especially under sunlight. The fundamental reason for ice melt under sunlight is related to the imbalanced energy flows of the incoming sunlight and outgoing thermal radiation. Therefore, radiative cooling, which can balance the energy flows without energy consumption, offers a sustainable approach for ice protection. Here, we demonstrate that a hierarchically designed radiative cooling film based on abundant and eco-friendly cellulose acetate molecules versatilely provides effective and passive protection to various forms/scales of ice under sunlight. This work provides inspiration for developing an effective, scalable, and sustainable route for preserving ice and other critical elements of ecosystems.

Nisoldipine in Several Aqueous and Non-Aqueous Cosolvent Solutions: Solubility Modeling and Preferential Solvation Research

The study mainly reported the equilibrated solubilities of nisoldipine in aqueous solutions of n-propanol/acetonitrile + water and non-aqueous solutions of ethyl acetate + ethanol/isopropanol by dint of experimentation and model correlations. Solubility was experimented via the shake-flask method under 101.2 kPa from 278.15 to 318.15 K. The maximum of nisoldipine solubility (in mole fraction unit) was found in neat n-propanol/acetonitrile/ethyl acetate at 318.15 K, and the minimum was found in neat water/isopropanol/ethanol. The total and three-dimensional Hansen solubility parameters were employed herein to explain the solubility behavior of nisoldipine. Modeling solubility through mixture response surface, Jouyban–Acree, and Jouyban–Acree–van’t Hoff models resulted in relative average deviations of <10.3%. Quantitative research upon preferential solvation was carried out by applying the approach of inverse Kirkwood–Buff integrals for the four solution systems considered in the present study and two aqueous solutions of ethanol/isopropanol reported in the literature. The local fractions of n-propanol/acetonitrile/ethanol/isopropanol for the four aqueous solutions as well as ethyl acetate for non-aqueous solution of ethyl acetate + isopropanol were greater than that of bulk ones in n-propanol/acetonitrile/ethanol/isopropanol/ethyl acetate-rich and middle composition proportions, demonstrating that the solvation of nisoldipine was preferred by cosolvents (n-propanol/acetonitrile/ethanol/isopropanol/ethyl acetate). It is able to speculate that nisoldipine displays Lewis acid behavior in these regions with the cosolvent molecules in aqueous solution systems and with the ethyl acetate molecules or isopropanol in the ethyl acetate + isopropanol solution system.

The Escherichia coli two-component signal sensor BarA binds protonated acetate via a conserved hydrophobic-binding pocket

The BarA/UvrY two-component signal transduction system is widely conserved in γ-proteobacteria and provides a link between the metabolic state of the cells and the Csr posttranscriptional regulatory system. In Escherichia coli, the BarA/UvrY system responds to the presence of acetate and other short-chain carboxylic acids by activating transcription of the noncoding RNAs, CsrB and CsrC, which sequester the RNA-binding protein CsrA, a global regulator of gene expression. However, the state of the carboxyl group in the acetate molecule, which serves as the BarA stimulus, and the signal reception site of BarA remain unknown. In this study, we show that the deletion or replacement of the periplasmic domain of BarA and also the substitution of certain hydroxylated and hydrophobic amino acid residues in this region, result in a sensor kinase that remains unresponsive to its physiological stimulus, demonstrating that the periplasmic region of BarA constitutes a functional detector domain. Moreover, we provide evidence that the protonated state of acetate or formate serves as the physiological stimulus of BarA. In addition, modeling of the BarA sensor domain and prediction of the signal-binding site, by blind molecular docking, revealed a calcium channels and chemotaxis receptors domain with a conserved binding pocket, which comprised uncharged polar and hydrophobic amino acid residues. Based on the comparative sequence and phylogenetic analyses, we propose that, at least, two types of BarA orthologues diverged and evolved separately to acquire distinct signal-binding properties, illustrating the wide adaptability of the bacterial sensor kinase proteins.

N-acetyl l-aspartate and Triacetin modulate tumor suppressor MicroRNA and class I and II HDAC gene expression induce apoptosis in Glioblastoma cancer cells in vitro

Glioblastoma multiforme (GBM), grade IV glioma and is aggressive, malignant primary brain cancer. Altered expression and activity of epigenetic proteins such as histone deacetylases (HDACs) are involved in GBM metastasis. Also, acetates are important to brain metabolites that regulate cell proliferation and apoptosis. Here, we have examined the effect of the acetates on the cell-cycle. U87MG cancer cells treated with N-acetyl l-aspartate (NAA) and sodium acetate have exhibited G1 phase cell-cycle arrest whereas U87MG cells treated with Triacetin (TA), and potassium acetate has induced G2/M cell cycle arrest. We have observed inhibition of histone deacetylase (HDAC) mRNA levels in acetate treated U87MG cells. Interestingly, acetates-treated U87MG cells have shown a significant reduction in the mRNA level of class II HDACs than class I HDACs. Acetate treated cells have exhibited an enhanced expression of various microRNAs such as miR-15b, miR-92, miR-101, miR-155, miR-199, miR-200, miR-223, miR-16, and miR-17 that are involved in the inhibition of cancer cell proliferation, invasion, migration, and angiogenesis. Further, these acetate molecules regulate genes involved in mammalian target of rapamycin complex 2 (mTORC2) such as mammalian stress-activated protein kinase-interacting protein (mSIN1), protein observed with Rictor 2 (Protor 2), and protein kinase C α (PKCα). The present study reveals the possible involvement of the mTORC2 complex during acetate-mediated HDAC inhibition, as well as microRNA modulation. Furthermore, molecular modeling studies were employed to understand the binding mode of these acetate molecules to mTOR, Rapamycin-insensitive companion of mammalian target of rapamycin (Rictor), and HDAC-8 proteins. Thus in this study, we have identified the pivotal role of acetates in the modulation of mTOR complex, epigenetic genes and provide structural as well as functional insights that will help in future drug discovery against GBM cancer therapy.

Features of radical copolymerization initiated by manganese triacetylacetonate

A comprehensive study of the kinetics of reactions of binary copolymerization of vinyl acetate with N-vinyl (N-vinylsuccinimide and N-vinyl-3(5)-methylpyrazole) and acrylic (2-hydroxyethylmethacrylate) monomers in different media was conducted. It is shown that the use of manganese triacetylacetonate as an initiator makes it possible to bring together the relative activities of monomers due to the complexation of manganese trisacetylacetonate and vinyl acetate molecules. This leads to a change in the microstructure of copolymers and to the production of macrochains with improved interleaving of monomeric links.

Structural Origin and Vibrational Fingerprints of the Ultrafast Excited State Proton Transfer of the Pyranine-Acetate Complex in Aqueous Solution.

The excited state proton transfer (ESPT) reaction from the photoacid 8-hydroxypyrene-1,3,6-trisulfonic acid (HPTS or pyranine) to an acetate molecule has been investigated in explicit aqueous solution via excited state ab initio molecular dynamics simulations based on hybrid quantum/molecular mechanics (QM/MM) potentials. In all the trajectories, the direct proton transfer has been observed in the excited state within 1 ps. We find that the initial structural configuration extracted from the ground state distribution strongly affects the ESPT kinetics. Indeed, the relative orientation of the proton donor-acceptor pair and the presence of a water molecule hydrogen bonded to the phenolic acid group of the pyranine are the key factors to facilitate the ESPT. Furthermore, we analyze the vibrational fingerprints of the ESPT reaction, reproducing the blue shift of the acetate CO stretching (COac), from 1666 to 1763 cm-1 testifying the transformation of acetate to acetic acid. Finally, our findings suggest that the acetate CC stretching (CCac) is also sensitive to the progress of the ESPT reaction. The CCac stretching is indeed ruled by the two vibrational modes (928 and 1426 cm-1), that in the excited state are alternately activated when the proton is shared or bound to the donor/acceptor, respectively.

Three metal(II) complexes constructed using the 2-(1H-benzo[d]imidazol-2-yl)quinoline ligand

Abstract 2-(1H-benzo[d]imidazol-2-yl)quinoline (BQ) as ligand and three coordination compounds of formula {Zn(BQ)Cl2} (1), {Pb(BQ)Cl2} n (2) and {[Cu(BQ)2(OC(O)CH3)]OC(O)CH3 · CH3COOH} (3) have been synthesized and fully characterized. The complexes crystallize in triclinic space group P 1 ‾ $P&amp;#x203e;{1}$ . In complexes 1 and 2, the coordination geometry is a distorted tetrahedral environment around the zinc center and a distorted sixfold coordination geometry around the lead center, respectively. In complex 3 the central Cu(II) center is in a trigonal bipyramidal coordination geometry. The Cu(II) ion is surrounded by two bidentate 2-(2′-quinolyl)benzimidazole (BQ) ligands and one coordinated acetate molecule. One further acetate anion associated by a strong hydrogen bond with a molecule of acetic acid balances the charge of the compound.

Effect of position of OH group in isomeric butanediols on intermolecular interaction with Choline Acetate: A thermodynamic study at different temperatures

The prominent effect of the position of hydroxyl groups in isomeric butanediols i.e.1,3-butanediol (1,3-BTD), 1,2-butanediol (1,2-BTD) and 2,3-butanediol (2,3-BTD) on intermolecular interactions with Choline Acetate has been investigated using various thermophysical parameters such as density ρ, speed of sound u, refractive index nD and specific conductivity κ over different concentration range and at temperatures varying from 293.15 to 323.15 K at atmospheric pressure. To gain further insight the derived parameters such as apparent molar volumes Vϕ, apparent molar isentropic compressibilities Ksϕ, and their infinite parameters mainly limiting apparent molar volumes at infinite dilution Vϕo, limiting apparent molar expansibilities Eϕo, limiting isentropic compression Kϕo, molar refraction Rm and infinite molar conductance ̂mo values have been calculated. The least values obtained for apparent molar volumes and compressibilities in case of 1,3-BTD mixtures are attributed to its highest ability to form intramolecular hydrogen bonding among isomeric butanediols and thus lesser availability to interact with Choline Acetate molecules. However for 2,3-BTD and 1,2-BTD binary mixtures the results have been explained on the basis of hydrophobic or iceberg effect where alkyl groups are present either on one end (1,2-BTD) or at both ends (2,3-BTD) while OH groups are located at vicinal carbon atoms.

Water-Mediated Excited State Proton Transfer of Pyranine-Acetate in Aqueous Solution: Vibrational Fingerprints from Ab Initio Molecular Dynamics.

In this work, we simulate the excited state proton transfer (ESPT) reaction involving the pyranine photoacid and an acetate molecule as proton acceptor, connected by a bridge water molecule. We employ ab initio molecular dynamics combined with an hybrid quantum/molecular mechanics (QM/MM) framework. Furthermore, a time-resolved vibrational analysis based on the wavelet-transform allows one to identify two low frequency vibrational modes that are fingerprints of the ESPT event: a ring wagging and ring breathing. Their composition suggests their key role in optimizing the structure of the proton donor–acceptor couple and promoting the ESPT event. We find that the choice of the QM/MM partition dramatically affects the photoinduced reactivity of the system. The QM subspace was gradually extended including the water molecules directly interacting with the pyranine–water–acetate system. Indeed, the ESPT reaction takes place when the hydrogen bond network around the reactive system is taken into account at full QM level.

Interaction studies of glycine, acetate and methylamine on β-tellurene nanoribbon – A first-principles analysis

We investigated the structural stability of β-tellurene nanoribbon (β-TeNR) and explored the adsorption behaviour of glycine, acetate, and methylamine malodorous molecules on β-TeNR based on ab-initio calculations. Besides, β-TeNR exhibits semiconducting behaviour with a direct energy gap (Eg) of 1.657 eV. In the beginning, the dynamical solidity and geometrical firmness were confirmed with regard to the phonon band spectrum and negative cohesive energy (−3.406 eV/atom), respectively. With the support of band structure and PDOS (projected-density of states), the electronic characteristics of β-TeNR are explored. Provocatively, two dissimilar superior adsorption sites (top &hollow-sites) of chief malodorous on β-TeNR were demonstrated with regard to the average band gap variation (Ega), Bader charge transfer (Q), and binding energy (EB). The calculated EB of preferential interaction sites is found to be in the scope of −0.190 to −1.751 eV referring to mixed physisorption and chemisorption type of interaction upon β-TeNR. The outcomes recommend that β-TeNR can be positively utilised as a chemi-resistor to sense the glycine, acetate, and methylamine molecules in an unpleasant atmosphere.

Structural Insights into a Bifunctional Peptide Methionine Sulfoxide Reductase MsrA/B Fusion Protein from Helicobacter pylori.

Methionine sulfoxide reductase (Msr) is a family of enzymes that reduces oxidized methionine and plays an important role in the survival of bacteria under oxidative stress conditions. MsrA and MsrB exist in a fusion protein form (MsrAB) in some pathogenic bacteria, such as Helicobacter pylori (Hp), Streptococcus pneumoniae, and Treponema denticola. To understand the fused form instead of the separated enzyme at the molecular level, we determined the crystal structure of HpMsrABC44S/C318S at 2.2 Å, which showed that a linker region (Hpiloop, 193–205) between two domains interacted with each HpMsrA or HpMsrB domain via three salt bridges (E193-K107, D197-R103, and K200-D339). Two acetate molecules in the active site pocket showed an sp2 planar electron density map in the crystal structure, which interacted with the conserved residues in fusion MsrABs from the pathogen. Biochemical and kinetic analyses revealed that Hpiloop is required to increase the catalytic efficiency of HpMsrAB. Two salt bridge mutants (D193A and E199A) were located at the entrance or tailgate of Hpiloop. Therefore, the linker region of the MsrAB fusion enzyme plays a key role in the structural stability and catalytic efficiency and provides a better understanding of why MsrAB exists in a fused form.