CHEMBIOCHEM
·
2022
·Vol. 24
·期 3
·e202200529
·
IF 3.461
Yu Yan,Chenni Zheng,Wei Song,Jing Wu,Liang Guo,Cong Gao,Jia Liu,Xiulai Chen,Meng Zhu,Liming Liu
Graphical Based on the resolved crystal structure (PDB code: 7X53), a protein engineering strategy was developed in CYP238A1 and an optimal CYP238A1 NPV variant containing a local hydrophobic “fence” at the active site was obtained, which increased the H 2 O 2 -dependent norbornene (NBE) epoxidation activity by 7.5-fold compared with that of CYP238A1 WT and switched the monooxygenase mode to the peroxygenase mode. Epoxy-norbornane (EPO-NBE) is a crucial building block for the synthesis of various biologically active heterocyclic systems. To develop an efficient protocol for producing EPO-NBE using norbornene (NBE) as a substrate, cytochrome P450 enzyme from Pseudomonas putida (CYP238A1) was examined and its crystal structure (PDB code: 7X53) was resolved. Molecular mechanism analysis showed a high energy barrier related to iron-alkoxy radical complex formation. Therefore, a protein engineering strategy was developed and an optimal CYP238A1 NPV variant containing a local hydrophobic “fence” at the active site was obtained, which increased the H 2 O 2 -dependent epoxidation activity by 7.5-fold compared with that of CYP238A1 WT . Among the “fence”, Glu255 participates in an efficient proton transfer system. Whole-cell transformation using CYP238A1 NPV achieved an EPO-NBE yield of 77.6 g ⋅ L −1 in a 30-L reactor with 66.3 % conversion. These results demonstrate the potential of this system for industrial production of EPO-NBE and provides a new biocatalytic platform for epoxidation chemistry.
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INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES
·
2020
·Vol. 21
·期 17
·6250
·
IF 4.556
Can Si,Jaime A. Teixeira da Silva,Chunmei He,Zhenming Yu,Conghui Zhao,Haobin Wang,Mingze Zhang,Jun Duan
The acetylation or deacetylation of polysaccharides can influence their physical properties and biological activities. One main constituent of the edible medicinal orchid,Dendrobium officinale, is water-soluble polysaccharides (WSPs) with substitutedO-acetyl groups. BothO-acetyl groups and WSPs show a similar trend in different organs, but the genes coding for enzymes that transfer acetyl groups to WSPs have not been identified. In this study, we report that REDUCED WALL ACETYLATION (RWA) proteins may act as acetyltransferases. ThreeDoRWAgenes were identified, cloned, and sequenced. They were sensitive to abscisic acid (ABA), but there were no differences in germination rate and root length between wild type and35S::DoRWA3transgenic lines under ABA stress. Three DoRWA proteins were localized in the endoplasmic reticulum.DoRWA3had relatively stronger transcript levels in organs where acetyl groups accumulated thanDoRWA1andDoRWA2, was co-expressed with polysaccharides synthetic genes, so it was considered as a candidate acetyltransferase gene. The level of acetylation of polysaccharides increased significantly in the seeds, leaves and stems of three35S::DoRWA3transgenic lines compared to wild type plants. These results indicate that DoRWA3 can transfer acetyl groups to polysaccharides and is a candidate protein to improve the biological activity of other edible and medicinal plants.Keywords:acetyl groups;Dendrobium officinale;REDUCED WALL ACETYLATION;endoplasmic reticulum
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FOOD CHEMISTRY
·
2020
·
IF 6.306
Tao Bao,Xin Hao,Mohammad Rezaul Islam Shishir,Naymul Karim,Wei Chen
Jujube slices were pretreated by cold plasma for 15, 30, and 60 s on each side, followed by hot air drying at 50, 60, and 70 °C. Scanning electron microscopy investigation indicated that the application of cold plasma significantly changed the surface topography of jujube slice by etching larger cavities, which can facilitate moisture transfer and consequently enhance drying rate and effective diffusivity. Modified Henderson & Pabis model and Two‐term model were the two most recommended models for describing the drying kinetics of jujube slices. Cold plasma pretreatment improved the contents of procyanidins, flavonoids, and phenolics by 53.81%, 33.89%, and 13.85% at most, respectively, and thereby enhanced antioxidant capacity by 36.85% at most. Besides, cold plasma pretreatment can reduce the production of 5-hydroxymethylfurfural by 52.19% at most. In summary, cold plasma can be used as a promising pretreatment tool for drying processes of jujube slices.
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METABOLIC ENGINEERING
·
2019
·
IF 7.808
Chaoning Liang,Xuanxuan Zhang,Jieyuan Wu,Shanshan Mu,Zhe Wu,Jian-Ming Jin,Shuang-Yan Tang
To mimic the delicately regulated metabolism in nature for improved efficiency, artificial and customized regulatory components for dynamically controlling metabolic networks in multiple layers are essential in laboratory engineering. For this purpose, a novel regulatory component for controlling vanillin biosynthetic pathway was developed through directed evolution, which was responsive to both the product vanillin and substrate ferulic acid , with different capacities. This regulatory component facilitated pathway expression via dynamic control of the intracellular substrate and product concentrations. As vanillin is an antimicrobial compound, low pathway expression and vanillin formation levels enabled better cell growth at an early stage, and the product feedback-activated pathway expression at later stages significantly improved biosynthesis efficiency. This novel multiple-layer dynamic control was demonstrated effective in managing the trade-off between cell growth and production, leading to improved cell growth and vanillin production compared to the conventional or quorum-sensing promoter-controlled pathway. The multiple-layer dynamic control enabled by designed regulatory components responsive to multiple signals shows potential for wide applications in addition to the dynamic controls based on biosynthetic intermediate sensing and quorum sensing reported to date.
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Water
·
2022
·Vol. 14
·期 17
·2595
·
IF 3.53
Wenjie Xu,Minghan Luo,Xinyue Lu,Zhengfang Ye,Taeseop Jeong
The removal of nitrate (NO3−-N) and antibiotics in aquaculture tail water is urgent and necessary. A lab-scale up-flow immobilized biofilter (I-BF) filled with polyurethane foam (PUF) carriers and a microbial consortium was developed for simultaneous removal of nitrate and tetracycline (TC). The denitrification and TC removal performance of the I-BF reactor was investigated under different TC concentrations (0, 10, 50, 100 mg·L−1), carbon/nitrogen (C/N) ratio (2, 4, 5, 6) and hydraulic retention times (HRT) (4, 8, 12 h). Simultaneous removal of nitrogen and TC was achieved by the I-BF reactor. Low TC concentration (≤50 mg·L−1) had little effect on nitrogen removal. The denitrification performance of the I-BF reactor was inhibited at high TC load, which may be attributed to the damage of cell membranes and the inhibition of the intracellular denitrification enzymes’ activities. The optimal C/N ratio and HRT were 5 h and 8 h with almost complete denitrification and high TC removal efficiency (73.46%) at influent NO3−-N and TC concentrations of 100 mg·L−1and 50 mg·L−1, respectively. The I-BF reactor proposed in this study has promising applications such as the treatment of piggery wastewater, aquaculture tail water and pharmaceutical wastewater co-contaminated with nitrate and antibiotics.Keywords:denitrification;tetracycline;immobilized biofilter reactor
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LANGMUIR
·
2022
·
IF 4.331
Mengting Lv,Huanan Li,Hua Cao,Teng Wang,Chengdian He,Yi Liang,Xiang Mao,Zhenyu Wang
This paper presents the fabrication of an alkaline-responsive drug carrier, chitosan@giant liposome (CS-GL), by using an ultrasound-integrated microfluidic approach. On the microfluidic chip, water/oil/water droplets are first prepared and then move through an area of ultrasonic radiation to improve the regional saturation of organic solvent and accelerate its removal. At the same time, phospholipid molecules in the oil phase of the droplets are efficiently self-assembled into giant liposomes (GLs). Subsequently, microfluidic channels combined with an up–down separated structure can help in the fabrication and purification of the GLs. Due to the electrostatic interaction between the amino group of chitosan and the phosphate group of phospholipids, the GLs and chitosan are assembled into CS-GLs. The change of ζ potential after this operation indicates that chitosan is coated on the surface of GLs. The formed CS-GLs are monodispersed with a 54.1 ± 0.7 μm diameter and high drug encapsulation efficiency (∼96%), and the structural integrity can be kept without leakage of contents for more than a week in an acid medium (pH = 1.2). When this structure is placed in an aqueous solution of pH = 7.8, chitosan precipitates gradually and detaches from the GL, causing its rupture. The drug encapsulated in a single CS-GL can be rapidly released within 4 s, and 99.6% of the CS-GL carriers can complete the release within 10 min.
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Journal of Materials Chemistry A
·
2020
·Vol. 8
·期 31
·15774-15781
·
IF 11.301
Xiangjian Meng,Weiliang Qi,Wandi Kuang,Samira Adimi,Haichuan Guo,Tiju Thomas,Siqi Liu,Zhenping Wang,Minghui Yang
Transition metal nitrides (TMNs) are emerging as a feasible alternative to noble metal co-catalysts in photocatalytic hydrogen production. Considering the recent prospects created by multicomponent systems, it is reasonable to investigate multi-component TMNs for photocatalytic hydrogen production. Herein, in an effort in that direction, ternary chromium-titanium nitride (Cr0.5Ti0.5N) nanoparticles have been synthesized by a solid–solid phase separation method, resulting in highly efficient co-catalysts for promoting photocatalytic hydrogen production of semiconductors under visible light irradiation. Both experimental results and density functional theory (DFT) calculations demonstrate that ternary Cr0.5Ti0.5N offers a comprehensive advantage by boosting the photo-induced charge carrier separation and migration, improving the reaction kinetics as compared to those of TiN and CrN. Therefore, the optimal Cr0.5Ti0.5N-based sample exhibits the highest photocatalytic hydrogen evolution rate of 2.44 mmol g−1 h−1, and has ∼120 times better kinetics than the reference pure CdS sample. In fact, this result even surpasses that of Pt-based nanocomposites (2.06 mmol g−1 h−1).
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JOURNAL OF MOLECULAR LIQUIDS
·
2020
·
IF 5.065
Chenglong Shi,Hongxia Li,Bing Liu,Yaru Qin,Guixiu Song
A new functionalized ionic liquid (FIL), tetrabutylammonium 2-ethylhexyl hydrogen-2-ethylhexylphosphonate ([N 4444 ][EHEHP]), was prepared and used in the extraction of lithium ion from aqueous solution. The factors affecting the extraction efficiencies, such as aqueous acidity, extractant concentration and temperature, were optimized. The mechanism involved in the extraction system was analyzed by slope analysis and FT-IR data. According to the Van't Hoff equation, the thermodynamic functions of the extraction reaction in ionic liquid system were obtained. Liquid/liquid extraction tests indicated that the ionic liquid system exhibited better selectivity towards lithium ions in the solution containing alkali metal ions . In addition, the quantitative stripping of lithium ions from the loaded ionic liquid phase was carried out and the effect of hydrochloric acid concentration on stripping rate was investigated in detail.
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Advanced Healthcare Materials
·
2021
·Vol. 11
·期 2
·2101702
·
IF 9.933
Yuchen Zhang,Liqi Li,Yanan Li,Yang Fei,Chencheng Xue,Xuemei Yao,Youbo Zhao,Xuan Wang,Menghuan Li,Zhong Luo
Ferroptosis is an emerging antitumor option and has demonstrated unique advantages against many tumor indications. However, its efficacy is potentially hindered by the endogenous lipid peroxide-scavenging mechanisms and the reliance on acidic pH. Herein, a nanointegrated strategy based on clinically-safe components to synergistically remodel glutathione and lactate metabolism in tumor cells for enhanced ferroptosis therapy is developed. First ferrocene is conjugated on PEGylated polyamidoamine dendrimers via reactive oxygen species (ROS)-cleavable thioketal linkage, which would further self-assemble with the glutathione (GSH)-depleting agent diethyl maleate (DEM) and monocarboxylate transporter 4-inhibiting siRNA (siMCT4) to afford biostable nanoassemblies (siMCT4-PAMAM-PEG-TK-Fc@DEM). The nanoassemblies can be activated by the elevated ROS levels in tumor intracellular environment and readily release the incorporated therapeutic contents, afterward DEM can directly conjugate to GSH to disrupt the glutathione peroxidase 4 (GPX4)-mediated antioxidant defense, while siMCT4 can block the MCT4-mediated efflux of lactic acid and acidify the intracellular milieu, both of which can improve the ferrocene-catalyzed lipid peroxidation and induce pronounced ferroptotic damage. The siMCT4-PAMAM-PEG-TK-Fc@DEM nanoplatform demonstrates high ferroptosis-based antitumor potency and good biocompatibility in vitro and in vivo, which may offer new avenues for the development of more advanced antitumor therapeutics with improved translatability.
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FOOD AND AGRICULTURAL IMMUNOLOGY
·
2018
·
IF 2.568
Wenliang Ge,Steven Suryoprabowo,Liguang Xu,Qiankun Zheng,Hua Kuang
A rapid, simple, sensitive immunochromatographic strip test was developed to detect penbutolol (PB) in pig urine based on a sensitive and specific monoclonal antibody produced in our laboratory. The antigen (PB-ovalbumin) and a goat anti-mouse IgG antibody were drawn onto a nitrocellulose membrane as the test line and control line, respectively. Under optimised conditions, the semi-quantitative test strip detected PB at concentrations of 2.5 ng/mL in 0.01 M PBS (pH 7.4) and 0.5 ng/mL in pig urine. All results were obtained within 5 min. Our data indicate that this immunochromatographic assay can be used for the sensitive, rapid, and specific on-site screening of PB.
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ELECTROCHIMICA ACTA
·
2020
·
IF 6.215
Ruinan Li,Yaqi Li,Rupeng Zhang,Mengxue He,Yulin Ma,Hua Huo,Pengjian Zuo,Geping Yin
Magnesium is considered one of the most promising anode materials. However, it is easy to react with electrolyte to form an ionic insulating passive film, causing a common phenomenon of voltage hysteresis and the resultant deteriorated electrochemical performance for magnesium batteries . Here, the voltage hysteresis of magnesium-sulfur batteries in Mg(ClO 4 ) 2 electrolyte is confirmed to be a consequence of magnesium passivation through three-electrode test and electrochemical impedance spectroscopy (EIS) measurements. The continuous competition relation between the formation and destruction of the passive film during magnesium stripping is discovered. The destruction process is controlled by the current density on magnesium anode, and the formation process is mainly affected by the concentration of anions causing passivation. Bromide ions as electrolyte additive can protect the magnesium surface from ClO 4 − anions and regulate the composition and thickness of the surface film, and the passivation of magnesium and the voltage hysteresis can be suppressed obviously. This work provides an important reference for further regulation of passivation behavior of magnesium anode.
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Nature Communications
·
2019
·Vol. 10
·期 1
·1-13
·
IF 11.878
Liu Xin,Li Yi,Xue Jiandang,Zhu Weikang,Zhang Junfeng,Yin Yan,Qin Yanzhou,Jiao Kui,Du Qing,Cheng Bowen,Zhuang Xupin,Li Jianxin,Guiver Michael D.
Proton exchange membranes with short-pathway through-plane orientated proton conductivity are highly desirable for use in proton exchange membrane fuel cells. Magnetic field is utilized to create oriented structure in proton exchange membranes. Previously, this has only been carried out by proton nonconductive metal oxide-based fillers. Here, under a strong magnetic field, a proton-conducting paramagnetic complex based on ferrocyanide-coordinated polymer and phosphotungstic acid is used to prepare composite membranes with highly conductive through-plane-aligned proton channels. Gratifyingly, this strategy simultaneously overcomes the high water-solubility of phosphotungstic acid in composite membranes, thereby preventing its leaching and the subsequent loss of membrane conductivity. The ferrocyanide groups in the coordinated polymer, via redox cycle, can continuously consume free radicals, thus helping to improve the long-term in situ membrane durability. The composite membranes exhibit outstanding proton conductivity, fuel cell performance and durability, compared with other types of hydrocarbon membranes and industry standard Nafion ® 212.
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