Bioresources and Bioprocessing
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2021
·Vol. 8
·期 1
·1-15
·
IF 4.578
Tan Xu,Zhang Sheng,Song Wei,Liu Jia,Gao Cong,Chen Xiulai,Liu Liming,Wu Jing
In this study, a four-enzyme cascade pathway was developed and reconstructed in vivo for the production of d - p -hydroxyphenylglycine (D-HPG), a valuable intermediate used to produce β-lactam antibiotics and in fine-chemical synthesis, from l -tyrosine. In this pathway, catalytic conversion of the intermediate 4-hydroxyphenylglyoxalate by meso -diaminopimelate dehydrogenase from Corynebacterium glutamicum ( Cg DAPDH) was identified as the rate-limiting step, followed by application of a mechanism-guided “conformation rotation” strategy to decrease the hydride-transfer distance d (C6HDAP−C4NNADP) and increase Cg DAPDH activity. Introduction of the best variant generated by protein engineering ( Cg DAPDH BC621/D120S/W144S/I169P with 5.32 ± 0.85 U·mg −1 specific activity) into the designed pathway resulted in a D-HPG titer of 42.69 g/L from 50-g/L l -tyrosine in 24 h, with 92.5% conversion, 71.5% isolated yield, and > 99% enantiomeric excess in a 3-L fermenter. This four-enzyme cascade provides an efficient enzymatic approach for the industrial production of D-HPG from cheap amino acids.
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ACS Biomaterials Science & Engineering
·
2020
·
IF 4.152
Bo Li,Ying Chen,Jisu He,Jing Zhang,Song Wang,Wenqian Xiao,Zhongning Liu,Xiaoling Liao
Nanofibrous poly(l-lactic acid) (PLLA) membrane-simulated extracellular matrices (ECMs) can be used in the biomedical field. However, the hydrophobic nature and poor osteoinductive property of PLLA limit its application in guided bone regeneration (GBR). In this work, a methacrylated gelatin/nano-HA (GelMA/nHA) complex was first synthesized in situ and then introduced into PLLA to fabricate biomimetic GelMA/nHA/PLLA membranes, mimicking the nanofibrous architecture and composition of ECMs by electrospinning and photocrosslinking. Compared to PLLA and GelMA/PLLA membranes, the novel GelMA/nHA/PLLA membranes demonstrated better tensile, hydrophilic, water sorption, and degradation properties. An in vitro biological evaluation indicated that the membranes promoted human bone marrow-derived mesenchymal stem cell (hBMSC) proliferation, adhesion, and osteogenic differentiation. Critical-sized defects in rat models were used to evaluate the bone regeneration performances of the three kinds of membranes in vivo, and the GelMA/nHA/PLLA membranes demonstrated excellent osteogenic regeneration potential. Therefore, GelMA/nHA/PLLA membranes have wide application prospects in bioengineering applications such as GBR treatment.
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INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
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2020
·
IF 5.162
Yu Chen,Shidong Liu,Caiyan Wan,Guangxian Zhang
A novel flame retardant (FR), the ammonium salt of citrulline-penta (methylphosphonic acid) (ACPMPA) based on L-citrulline was synthesized, and its structure was characterized by 13 C, 1 H, and 31 P nuclear magnetic resonance (NMR) spectroscopy. The ACPMPA flame retardant molecule contains five ammonium salts of phosphorus acid and one ammonium salt of carboxylic acid, which allowed the covalent attachment of ACPMPA onto cellulose via -P=O(-O-C) and –COOC bonds. The results showed that the treated cotton fabrics had very high flame retardance and excellent durability. The limiting oxygen index (LOI) of cotton fabric treated with 35%-ACPMPA reached 49.2% and only decreased to 34.2% after 50 laundry cycles. Vertical flame tests also demonstrated that the treated cotton fabric acquired good flame retardance. The thermogravimetry (TG) and TG-IR results showed that the treated cotton left more residues and released almost no flammable volatiles at high temperatures. The cone calorimetry results showed that the treated cotton released less heat than pure cotton. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) results demonstrated that the structure of the treated cotton fabric was almost unchanged, and no free formaldehyde was detected, indicating that the treated cotton was safe. The treated cotton fabric also retained good tensile strength and whiteness.
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JOURNAL OF CHROMATOGRAPHIC SCIENCE
·
2021
·Vol. 59
·期 4
·388-395
·
IF 1.618
Ma Xiaofei,Li Jingtang,Li Xiaoqi,Feng Zijie,Yang Xuan,Liu Jie,Du Yingxiang
Nowadays, ionic liquids (ILs) functionalized cyclodextrins (CDs) have drawn increasing attention in chiral separation. Herein, a novel β-CD derivative functionalized by L-histidinium IL, mono-6-deoxy-6-L-histidinium-β-cyclodextrin chloride (L-HMCDCl), was synthesized for the first time and utilized for enantioseparation of nefopam and chlorphenamine in capillary electrophoresis. The L-HMCDCl exhibited superior enantioselectivity compared with native β-CD. The effect of some key parameters such as chiral selector concentration, buffer pH and applied voltage on the enantioseparation was investigated in detail. In the interest of the chiral discrimination mechanism and the enhanced enantioselectivity of L-HMCDCl, molecular modeling with AutoDock was employed to study the interaction, which was in good agreement with experimental results.
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APPLIED MICROBIOLOGY AND BIOTECHNOLOGY
·
2020
·Vol. 104
·期 23
·10005-10018
·
IF 3.53
Guo Xiaolei,Wu Weibin,Zhang Mingliang,Wu Licheng,Huang Jianzhong
Abstract l -Tyrosine is a versatile compound used in the fine chemical, pharmaceutical, and functional food industries. Here, we report a bi-enzymatic cascade involving alanine racemase (ALR) and d -amino acid oxidase (DAAO) to produce pyruvate, as co-substrate for l -tyrosine production, from the cheap substrate l -alanine. The BpALR (ALR from Bacillus pseudofirmus ) was used as a whole-cell biocatalyst, converting l -alanine to d , l -alanine. The FsDAAO (DAAO from Fusarium solani ) was immobilized to oxidize the d -alanine generated in the first step to pyruvate. Both systems were combined as a continuous-flow reactor for maximized l -alanine-to-pyruvate conversion rates. The optimal parameters and appropriate conditions for FsDAAO immobilization were investigated. The pyruvate concentration of 86.6 g/L was achieved within 17 h. Subsequently, a whole-cell biocatalyst system for l -tyrosine production, catalyzed by the tyrosine phenol-lyase (TPL) from Erwinia herbicola (EhTPL), was developed, and a fed-batch approach was applied with phenol and the pyruvate produced with the ALR/DAAO system mentioned above. The concentration of phenol and pyruvate in the reactor should not exceed 7.5 g/L and 10 g/L, respectively. Significantly, the l -tyrosine concentration of 152.5 g/L was achieved within 10 h, demonstrating the great potential for high-efficiency production of l -tyrosine through the approach we established in this paper. Graphical abstract Key points • A specific bioreactor system for pyruvate produced from l -alanine was developed • The appropriate condition for immobilization of FsDAAO was investigated • A fed-batch process was established to produce l -tyrosine with recombinant E. coli • The bi-enzymatic cascade was successfully used for l -tyrosine production at low cost
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Food Science and Technology
·
2020
·
IF 1.443
REN Haiwei,DU Nana,NIU Xiaoqian,WANG Yonggang,TIAN Hui,CAO Yingying,ZHANG Binyun,FAN Wenguang
Polyphenol oxidase is the popular enzyme involved in fruit-vegetable browning and melanin synthesis. In the present paper, L-3-phenyllactic acid, a natural bacteriostatic substance, was investigated as an inhibitor of polyphenol oxidase. The results were demonstrated that the residual enzyme activity of polyphenol oxidase decreased gradually with the increase of the concentration of L-3-phenyllactic acid. The L and ΔE values of the reaction system increased gradually. The reversible mixed-type inhibition mode of L-3-phenyllactic acid was determined by Lineweaver Burk plot. At the same time, the results of fluorescence quenching demonstrated that L-3-phenyllactic acid was a quencher of polyphenol oxidase, and the molecular docking study provided the binding mode of L-3-phenyllactic acid and polyphenol oxidase at the molecular level. L-3-phenyllactic acid decreased the activity of polyphenol oxidase and browning of fresh-cut Agaricus Bosporus. This research first studied the inhibitory effect of L-3-phenyllactic acid on the activity of polyphenol oxidase, and would provide a theoretical foundation for the use of L-3-phenyllactic acid as anti-polyphenol oxidase agents.
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MOLECULES
·
2020
·Vol. 25
·期 8
·1825
·
IF 3.267
Yuanyang Dong,Qihang Hou,Meng Sun,Jingjing Sun,Bingkun Zhang
Plantago asiaticaL. is widely distributed in Eastern Asia and a commonly used drug in China, Korea, and Japan for diuretic and antiphlogistic purposes. In this experiment, the present study was performed to isolate antioxidant molecules based on the DPPH scavenging activity assay and discover the bioactive compounds which contributed to performing the function ofPlantago asiaticaL. Each faction was chosen for further isolation guided by DPPH scavenging activity assay. Afterwards, two potential bioactive molecules, aesculetin and apigenin, were isolated for in vitro antioxidant activity in cells. Hydrogen-peroxide-induced oxidative stress led to decreased cell viability, impaired intercellular junction, and damage to the cell membrane and DNA. Furthermore, aesculetin ameliorated decreased cell viability induced by hydrogen peroxide via upregulation of antioxidant related genes, and apigenin also protected against H2O2mainly by improving the glutathione (GSH) antioxidant system, such as increasing the activity of glutathione peroxidase (GPX), glutathione reductase (GR), and the ration of GSH/glutathione disulfide (GSSG). Above all, these findings suggest that aesculetin and apigenin may be bioactive compounds for antioxidant function inPlantago asiaticaL.Keywords:antioxidants;compound isolation;DPPH;Plantago asiaticaL.;aesculetin;apigenin
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Journal of Nanomaterials
·
2020
·
IF 1.98
Guoyong Wang,Chongxian He,Wengjing Yang,Fangwei Qi,Guowen Qian,Shuping Peng,Cijun Shuai
Graphene oxide (GO) usually serves as a reinforce phase in polymer because of its superior mechanical strength and high specific surface area. In this work, GO was grafted with L-lactic acid monomer (denoted as GO@PLLA) to overcome the aggregation in matrix and then incorporated into the poly-L-lactic acid (PLLA) scaffold fabricated by selective laser sintering. In hybrid scaffold, GO@PLLA exhibited uniform dispersion in the matrix. Furthermore, mechanical interlock between GO@PLLA and PLLA matrix formed and reinforced the interface bonding. On the other hand, the heterogeneous distributed GO acted as effective nucleating agent and resultantly enhanced the crystallization. Results showed that the tensile and compressive strength of scaffolds increased by 143.3% and 127.6%, respectively. Meanwhile, the scaffold exhibited an increased degradation rate of 37.9%, which could be attributed to the abundant hydrophilic functional groups on GO. Moreover, the scaffold exhibited favorable bioactivity and biocompatibility. Herein, the developed hybrid scaffold showed potential capacity for bone tissue engineering.
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JOURNAL OF THE AMERICAN OIL CHEMISTS SOCIETY
·
2020
·Vol. 97
·期 6
·603-614
·
IF 1.659
Jia Luo,Zeping Wang,Shangzhi Deng,Fan Zhang,Guirong Bao,Junni Mao,Wenjing Yang
Direct glycerolysis of novel edible Sacha Inchi ( Plukenetia volubilis L.) seed oil (PvLO) into diacylglycerols (DAG) and monoacylglycerols (MAG) was studied over solid Na 2 SiO 3 with or without microwave assistance. The glycerolysis yield was calculated by qualitative and semiquantitative analyses of 1 H NMR, 13 C NMR, and FT-IR spectra. The yields of ~33% 1, 3-DAG, ~16% 1, 2-DAG, ~40% 1-MAG, and ~2.3% 2-MAG were achieved after 16 hours at 120 °C in three consecutive cycles using acetone, with an interesterification rate of 92%. The modified oil showed enhanced gelation ability at low temperatures. The yield of 1, 2-DAG can be increased by adding acetone as solvent. The fatty acid compositions and unsaturated structure of lipids were less destroyed after alkaline glycerolysis. However, more α-linolenic and linoleic acids were transferred to the sn -2 position of glyceryl skeleton. The oxidative stability of the modified oil was still controllable. In summary, this work provides a feasible method to convert polyunsaturated plant oils into oils rich in DAG and MAG with less destructive impact on the olefinic structure of oil. Also, it provides a useful example of how to quickly evaluate the influence of chemical modification on the chemical structure of plant oils by using various spectral technologies.
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GREEN CHEMISTRY
·
2020
·Vol. 22
·期 13
·4222-4230
·
IF 9.48
Jiayuan Yu,Anker Degn Jensen,Lei Wang,Chunshan Li,Suojiang Zhang
Methacrolein (MAL) is an important chemical for the manufacture of methyl methacrylate and a key monomer in many polymerization reactions. In this study, L-proline was investigated as the catalyst for the aldol condensation of formaldehyde and propionaldehyde to produce MAL. The catalytic activity of the reaction system was closely related to the competition between the main reaction synthesizing MAL and the side reaction producing 2-methyl-2-pentenal, which could be modified by adjusting the operating parameters. The influences of several operating conditions, including temperature, reaction time and water content, on the catalytic performance of the system were systematically studied via a series of single-factor experiments, and the optimized reaction conditions were obtained. The mechanistic investigation via ESI-MS indicated that the reaction pathway followed the Mannich route. Experimental and theoretical kinetic analyses of the L-proline-catalyzed aldol condensation reaction were performed, and the reaction orders of the reactants were obtained by regression. The results showed that L-proline was an efficient catalyst for the production of MAL via aldol condensation under mild conditions.
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Science China-Chemistry
·
2020
·Vol. 63
·期 9
·1295-1305
·
IF 6.356
Wang Xianheng,Yang Lei,Yang Peng,Guo Wancai,Zhang Quan-Ping,Liu Xianhu,Li Yiwen
Melanin-inspired polymers are currently the focus of growing interest for a wide range of applications ranging from energy to biomedical area. Whilst researchers have made numerous attempts to prepare and utilize polydopamine nanoparticles (PDA NPs), they have made limited progress in developing and discovering another typical functional mimic of natural melanin, poly (levodopa) (P(L-DOPA)) NPs, probably due to the lack of facile synthetic strategies towards satisfactory structural and functional control of melanin-like NPs. Herein, we reported a one-pot preparation method towards P(L-DOPA) NPs with good yields and controllable size/property in an aqueous solution assisted by various metal ions ( i.e. , Ni(II), Mg(II), Ca(II), Fe(III), Mn(II), Co (II), Zn(II) and Cd(II)). Interestingly, the resulting P(L-DOPA) NPs exhibited enhanced light absorption and photothermal behaviors compared with well-established PDA NPs, which can be employed to further fabricate kinds of photothermal composite actuators with promising performances such as folding, switching, and forward-moving. This study offers a facile and robust way to synthesize new synthetic melanins beyond PDA, and facilitates further functional discovery and evolution of melanin-inspired polymers and composites.
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TOXICON
·
2020
·
IF 2.201
Qing Cao,Weijing Liu,Yurong Gu,Liqiang Xie,Weili Jiang,Yan Gao,Liuyan Yang
Heavy metals and microcystins commonly co-exist in water bodies with cyanobacteria, and have been shown to affect aquatic plants. However, their combined effects remain largely unknown. In this study, the toxic effects of copper (Cu) and cadmium (Cd) on Ceratophyllum demersum L. were characterized in the presence of microcystin-LR (MC-LR). The results showed that the bioaccumulation of MC-LR and Cu/Cd in C. demersum was significantly increased by the interaction between MC-LR and Cu/Cd. The combined toxicity assessment results suggested that the toxicities of Cu or Cd to C. demersum would be largely exacerbated by MC-LR, which could be the results of increased bioaccumulation of the pollutants. Cu, Cd and MC-LR, as well as their mixture, significantly decreased plant fresh weight and total chlorophyll content of C. demersum , especially at their high concentrations. The antioxidative system was activated to cope with the adverse effects of oxidative stress. Antioxidant enzyme activities were significantly stimulated by Cu, Cd and MC-LR, as well as their mixture. However, the decreased superoxide dismutase (SOD) and glutathione reductase (GR) activities were observed when exposed to relative high concentrations of Cu or Cd together with MC-LR of 5 μg L −1 . MC-LR brought more stress to the antioxidative system, which is another possible explanation for the synergistic effect. Our findings highlight increased ecological risks of the co-contamination of heavy metals and harmful cyanobacteria.
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