APPLIED AND ENVIRONMENTAL MICROBIOLOGY
·
2021
·Vol. 87
·期 6
·
IF 4.792
Minggen Cheng,Dongmei Pei,Xiangrong He,Yongchuang Liu,Pingping Zhu,Xin Yan
The bacterial hydrolytic dehalogenation of 4-chlorobenzoate (4CBA) is a coenzyme A (CoA)-activation-type catabolic pathway that is usually a common part of the microbial mineralization of chlorinated aromatic compounds. Previous studies have shown that the transport and dehalogenation genes for 4CBA are typically clustered as an fcbBAT1T2T3C operon and inducibly expressed in response to 4CBA. However, the associated molecular mechanism remains unknown. In this study, a gene (fcbR) adjacent to the fcb operon was predicted to encode a TetR-type transcriptional regulator in Comamonas sediminis strain CD-2. The fcbR knockout strain exhibited constitutive expression of the fcb cluster. In the host Escherichia coli, the expression of the Pfcb-fused green fluorescent protein (gfp) reporter was repressed by the introduction of the fcbR gene, and genetic studies combining various catabolic genes suggest that the ligand for FcbR may be an intermediate metabolite. Purified FcbR could bind to the Pfcb DNA probe in vitro, and the metabolite 4-chlorobenzyl-CoA (4CBA-CoA) prevented FcbR binding to the Pfcb DNA probe. Isothermal titration calorimetry (ITC) measurements showed that 4CBA-CoA could bind to FcbR at a 1:1 molar ratio. DNase I footprinting showed that FcbR protected a 42-bp DNA motif (5′-GGAAATCAATAGGTCCATAGAAAATCTATTGACTAATCGAAT-3′) that consists of two sequence repeats containing four pseudopalindromic sequences (5′-TCNATNGA-3′). This binding motif overlaps with the −35 box of Pfcb and was proposed to prevent the binding of RNA polymerase. This study characterizes a transcriptional repressor of the fcb operon, together with its ligand, thus identifying halogenated benzoyl-CoA as belonging to the class of ligands of transcriptional regulators.IMPORTANCE The bacterial hydrolytic dehalogenation of 4CBA is a special CoA-activation-type catabolic pathway that plays an important role in the biodegradation of polychlorinated biphenyls and some herbicides. With genetic and biochemical approaches, the present study identified the transcriptional repressor and its cognate effector of a 4CBA hydrolytic dehalogenation operon. This work extends halogenated benzoyl-CoA as a new member of CoA-derived effector compounds that mediate allosteric regulation of transcriptional regulators.
研究领域:
微生物学
·
分子生物学
·
环境科学
✓ 已验证
DOI
PubMed
高影响因子
APPLIED BIOCHEMISTRY AND BIOTECHNOLOGY
·
2014
·Vol. 173
·期 8
·2042-2053
·
IF 1.687
He Yu-Cai,Yang Zhen-Xing,Zhang Dan-Ping,Tao Zhi-Cheng,Chen Chao,Chen Yi-Tong,Guo Fei,Xu Jian-He,Huang Lei,Chen Rui-Jie,Ma Xiao-Feng
The reductase (PgCR) from recombinant Escherichia coli CCZU-Y10 displayed high reductase activity and excellent stereoselectivity for the reduction of ethyl 4-chloro-3-oxobutanoate (COBE) into ethyl ( S )-4-chloro-3-hydroxybutanoate (( S )-CHBE). To efficiently synthesize ( S )-CHBE (>99 % enantiomeric excess (ee)), the highly stereoselective bioreduction of COBE into ( S )-CHBE with the whole cells of E. coli CCZU-Y10 was successfully demonstrated in a dibutyl phthalate-water biphasic system. The appropriate ratio of the organic phase to water phase was 1:1 ( v / v ). The optimum reaction temperature, reaction pH, cosubstrate, NAD + , and cell dosage of the biotransformation of 100 mM COBE in this biphasic system were 30 °C, 7.0, mannitol (2.5 mmol/mmol COBE), 0.1 μmol/(mmol COBE), and 0.1 g (wet weight)/mL, respectively. Moreover, COBE at a high concentration of (1,000 mM) could be asymmetrically reduced to ( S )-CHBE in a high yield (99.0 %) and high enantiometric excess value (>99 % ee). Significantly, E. coli CCZU-Y10 shows high potential in the industrial production of ( S )-CHBE (>99 % ee).
研究领域:
生物化学
·
微生物学
·
合成生物学
✓ 已验证
DOI
PubMed
高影响因子
Journal of Cleaner Production
·
2024
·
IF 9.7
Jiahui Zhang,Wenliang Zhang,Yue Wang,Shaoyi Jiang,Yan Wang,Zhezheng Ding,Xiaomin Liu
2,4-dichlorophenoxyacetic (2,4-D) acid and 4-chlorophenoxyacetic acid (4-CPA), as widely utilized organochlorine pesticides , are normally detected in wastewater and atmosphere. Their harmfulness to the ecosystem cannot be ignored. UV/H 2 O 2 is one of the most conventional advanced oxidation processes, which has remarkable advantages for the removal of refractory organic pollutants in wastewater. However, the reaction mechanisms and pathways of pollutants with reactive radicals are still unclear. In this study, the degradation efficacy and mechanisms during the photodegradation of 2,4-D and 4-CPA in UV/H 2 O 2 processes were investigated by experiments and density functional theory calculations. The results showed that 2,4-D was more likely to be degraded by UV/H 2 O 2 treatment than UV photolysis alone. In contrast, 4-CPA can be degraded effectively and rapidly under UV irradiation alone. By LC-MS analysis, the degradation products of 2,4-D and 4-CPA in the UV/H 2 O 2 processes were identified and they were produced by hydroxylation and photolysis. Therefore, we speculated a competition mechanism presented between direct photolysis and indirect photolysis in the UV/H 2 O 2 degradation of 2,4-D and 4-CPA. The OH-initiated reaction mechanisms of 2,4-D and 4-CPA in aqueous environments were investigated using quantum chemical methods SMD/M06–2X/6–311++G (3df, 2p)//SMD/M06–2X/6-311 + G (d,p). The pH dependence of the reaction mechanisms and rate constants in their degradation process induced by ·OH was also investigated. The calculation results showed that the ionic forms (2,4-D - and 4-CPA - ) were more prone to react with ·OH in comparison to the corresponding molecular forms (2,4-D and 4-CPA). The total rate constants of 2,4-D and 4-CPA with OH increased with the pH from 1 to 10, and decreased with continued pH increase. The toxicities of 2,4-D, 4-CPA and their products were assessed by the QSAR-based toxicity evaluation software. The results showed that several products were more toxic than their parent compounds, such as 2,4-dichlorophenol, 3,5-dichlorocatechol, 4-chlorophenol and hydroquinone . This work can contribute to clarifying the environmental risks of 2,4-D and 4-CPA and offer a complete understanding for the photodegradation behavior of 2,4-D and 4-CPA in aqueous ecosystems.
研究领域:
环境科学
·
化学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF RAMAN SPECTROSCOPY
·
2018
·Vol. 49
·期 8
·1395-1401
·
IF 2.879
Caiqing Ma,Yu Liu,Jing Wang,Shiwei Wu,Qian Zhang,Peng Song,Lixin Xia
The coupling reaction of 4-nitrothiophenol to 4,4′-dimercaptoazobenzene was investigated by surface enhancement Raman scattering method. The reaction was found to be controlled by the compatibility of organic alkalis and silver nanoparticles. The effect of hot electron–hole pairs on the reaction was evaluated. Furthermore, the mechanism of organic alkalis affecting hot electron–hole pairs to achieve regulation of the coupling reaction of 4-nitrothiophenol to 4,4′-dimercaptoazobenzene was studied. A comprehensive analysis of the different surface enhancement Raman scattering signals collected was conducted. The forward-looking view of capturing holes through the hydrolysis of organic alkalis to ensure the integrity of the substrate was also presented.
研究领域:
化学
·
纳米科学
·
光谱学
✓ 已验证
产品关联
DOI
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2020
·
IF 3.573
Kun Wang,Rong Chen,Xun Zhu,Qiang Liao,Dingding Ye,Gang Chen,Ming Liu
In this study, a simple method for directly synthesizing Ag nanoparticles on the inner wall of a microreactor was proposed to catalytically convert 4-NP to 4-AP. The proposed method employed silver ammonia as the precursor and polydopamine (PDA) to modify the surface of the microreactor. Because PDA contains numerous reducing agents of phenolic hydroxyl groups, the silver ions can be effectively reduced to Ag nanoparticles. Moreover, due to the zwitterionic nature of PDA, the use of silver ammonia as a precursor, which intrinsically has a high pH value, can allow for more silver ions to be adsorbed on the surface than the conventionally used AgNO3 as a precursor. Accordingly, the precursor utilization could be greatly improved, leading to the increase of the catalyst loading and thereby boosting the catalytic conversion and durability. It was also found that an increase in the reduction time required for the catalyst preparation could lead to the increase of the catalyst loading and thereby the catalytic performance but a too long reduction time did not continue to make more contribution. Experimental results demonstrate that the microreactor prepared by this simple method is able to exhibit good catalytic activity and durability, providing a new approach for developing high-performance microreactors.
研究领域:
化学工程
·
纳米材料科学
·
环境催化
✓ 已验证
DOI
高影响因子
JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY
·
2017
·
IF 3.154
Lukai Ma,Guoqin Liu
A group of toxic aldehydes such as, malondialdehyde (MDA), 4-hydroxy-2-hexenal (HHE), and 4-hydroxy-2-nonenal (HNE) have been found in various vegetable oils and oil-based foods. Then simultaneous determination of them holds a great need in both the oil chemistry field and food field. In the present study, a simple and efficient analytical method was successfully developed for the simultaneous separation and detection of MDA, HHE, and HNE in vegetable oils by reversed-phase-high-performance liquid chromatography (RP-HPLC) coupled with photodiode array detector (PAD) at dual-channel detection mode. The effect of various experimental factors on the extraction performance, such as coextraction solvent system, butylated hydroxytoluene addition, and trichloroacetic acid addition were systematically investigated. Results showed that the linear ranges were 0.02–10.00 μg/mL for MDA, 0.02–4.00 μg/mL for HHE, and 0.03–4.00 μg/mL for HNE with the satisfactory correlation coefficient of >0.999 for all detected aldehydes. The limit of detection (LOD) and limit of quantification (LOQ) of MDA, HHE, and HNE were ∼0.021and 0.020 μg/mL, ∼0.009 and 0.020 μg/mL, and ∼0.014 and 0.030 μg/mL, respectively. Their recoveries were 99.64–102.18%, 102.34–104.61%, and 98.87–103.04% for rapeseed oil and 96.38–98.05%, 96.19–101.34%, and 96.86–99.04% for French fries, separately. Under the selected conditions, the developed methods was successfully applied to the simultaneous determination of MDA, HHE, and HNE in different tested vegetable oils. The results indicated that this method could be employed for the quality assessment of vegetable oils.
研究领域:
食品科学
·
分析化学
✓ 已验证
DOI
PubMed
高影响因子
INTERNATIONAL JOURNAL OF FOOD SCIENCE AND TECHNOLOGY
·
2019
·Vol. 55
·期 4
·1833-1842
·
IF 2.281
Lukai Ma,Guoqin Liu,Weiwei Cheng,Xinqi Liu,Huifan Liu,Qin Wang,Guoxing Mao,Xintong Cai,Charles Brennan,Margaret A. Brennan
Summary The present work investigated the formation of three toxic aldehydes, malondialdehyde (MDA), 4-hydroxy-hexenal (HHE) and 4-hydroxy-nonenal (HNE), during deep-frying of different foods in corn oil (CO), rapeseed oil (RO) and linseed oil (LO). Besides, their contents in French fries (FF) and fried chicken breast meat (FCBM) were also explored. Results showed that the MDA/HHE/HNE levels in frying groups were all lower than those in control, indicating the incorporation into the fried foods. Apart from the different levels, MDA/HHE/HNE in FF and FCBM possessed similar variation tendencies, revealing the matrix-mediated distribution. The combined exposure assessment based on the threshold of toxicological concern (TTC) levels was conducted, and risks of exceeding the limitation values (1.5 μg kg bw −1 day −1 ) for HNE in CO and HHE in LO were exhibited. The consumption of both FF and FCBM should be regulated, considering the levels of MDA, HHE and HNE these fried foods may contain.
研究领域:
食品科学
·
毒理学
·
营养学
✓ 已验证
产品关联
DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2017
·
IF 3.359
Qingxiang Zhou,Man Lei,Jing Li,Kuifu Zhao,Yongli Liu
Mg-Al-layered double hydroxide (Mg-Al-LDH) modified nanoscale zero-valent iron (NZVI) (Fe@MgAl-LDH) was firstly synthesized and characterized by several techniques. The results showed that the layered double hydroxides were coated on the surface of nanoscale zero-valent iron particles. This new material exhibited good adsorption for bisphenol A, 4-octylphenol and 4-nonylphenol from water samples. Based on these, a sensitive method was developed for the extraction and preconcentration of bisphenol A, 4-octylphenol and 4-nonylphenol using magnetic Fe@MgAl-LDH nanoparticles as the solid phase extraction adsorbents prior to high performance liquid chromatography coupled with variable wavelength detection. Under the optimal conditions, linear responses were achieved in the range of 0.5–200 μg L −1 with the correlation coefficients (r) above 0.999. The detection limits of three analytes were in the range of 0.24–0.34 μg L −1 , and precisions were all below 2.5% (n = 6). The proposed method was evaluated with real water samples and the excellent spiked recoveries in the range of 96.0–99.3% were achieved.
研究领域:
环境科学
·
分析化学
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL PAPERS
·
2023
·Vol. 77
·期 11
·6637-6646
·
IF 2.2
Chen Lei,Li Rongxin,Li Yuanlong,Shu Qijiang,Yang Tao
The reduced graphene oxide aerogel modified by 4-chlorophenyl sulfoxide was obtained by a simple self-assemble process under the basic reduction-oxide condition, then freeze-dried for future using. The prepared aerogel was shortly named 4CS-rGO, which was characterized by Fourier transform infrared spectroscopy, Raman spectroscopy, scanning electron microscope, et al. 1 mg of 4CS-rGO composite was used as an adsorbent to adsorb Pd(II) and Pt(IV) in 1.0 mL 40 mM Britton-Robinson buffer solution with various pH. The adsorption efficiency of Pd(II) increased with the increase in pH, whereas the hydrolysis of Pd(II) happened at pH 13, and the maximum adsorption efficiency of Pd(II) was 91.82% at pH 12, which was mainly driven by electrostatic attraction. Besides, the adsorption behavior of the 4CS-rGO composite for Pt(IV) was explored to evaluate the possibility to isolate Pd(II) and Pt(IV) ions by using aerogel. We found that, quite interestingly, hydrogen bond, hydrophobic interaction and van der Waals force can strongly conquer electrostatic repulsion driven Pt(IV) ions adsorption behavior at pH 5, and Pt(IV) ions displaced by cationic surfactant. Moreover, a tighter Pt(IV) ions adsorption behavior than Pd(II) ions was observed while we adsorb them respectively with/without 4-chlorophenyl sulfoxide modified the graphene, while branched TBAB was easier and more effectively replaced the adsorbed Pt(IV) ions than strained CTAB.
研究领域:
材料科学
·
环境化学
·
分析化学
✓ 已验证
产品关联
DOI
高影响因子
Sustainability
·
2022
·Vol. 14
·期 21
·14300
·
IF 3.889
Qinghong Wang,Siyu Li,Xin Wang,Zhuoyu Li,Yali Zhan,Chunmao Chen
The extensive use of pharmaceuticals and personal care products (PPCPs) causes high concentrations of pharmaceutical metabolites to exist in aquatic environments. Though the removal of parent PPCPs has raised concerns, the degradation of pharmaceutical metabolites was rarely investigated. In this study, the degradation of 4-acetylaminoantipyrine (4-AAA), a typical dipyrone metabolite frequently detected worldwide in surface water and wastewater, was initially studied using persulfate (PDS)-based advanced oxidation processes (AOPs). Compared with commonly used activation methods of alkali, ultrasonic, ultraviolet, and Fe2+, 4-AAA achieved its best degradation (98.9%) within 30 min in a thermally activated PDS system due to the promotion of both radical production and the reaction rate with the rise in temperature. The optimum degradation of 4-AAA could be achieved with the temperature of 80 °C regardless of initial pH values, indicating a wide suitable pH range. Moreover, over 80% of the degradation of 4-AAA could be achieved with the presence of Cl−(0–16 mM), HCO3−(0–8 mM), and humic acid (0–30 mg/L), further indicating the application potential of the system. Both sulfate radicals (SO4•−) and hydroxyl radicals (•OH) contributed to 4-AAA degradation and the contribution of •OH increased with the pH rising from 3 to 11 due to the transformation from SO4•−when reacting with OH−. Three hydroxylated and ring-opening intermediates were detected during the 4-AAA degradation. The ECOSAR prediction indicated that the acute toxicity of most intermediates decreased than 4-AAA while the chronic toxicity increased, which suggested the transformation of intermediates should be further focused on in SO4•−and •OH based AOPs. This study would provide technical reference for the control of 4-AAA in wastewater treatment processes, raise concerns on the influence of PPCPs metabolites, and throw light on reducing the harm of PPCPs and their metabolites in aquatic environments.Keywords:4-acetylaminoantipyrine (4-AAA);heat activation;persulfate;degradation pathway;toxicity
研究领域:
环境科学
·
水处理
·
高级氧化过程
✓ 已验证
产品关联
DOI
高影响因子
Molbank
·
2015
·Vol. 2015
·期 4
·M871
·
IF 0
Shuitao Yu,Xiaohu Feng,Weiyou Zhou,Zhengjun Xia,Mingguang Zhang,Yang Chen,Zaixin Chen
A new tetrahalogenated benzoic acid 4-chloro-2,3,5-trifluorobenzoic acid was synthesized from methyl 2,3,4,5-tetrafluorobenzoate via three steps. The structure of the newly synthesized compound was established by FTIR, NMR, MS and elemental analysis.Keywords:4-chloro-2,3,5-trifluorobenzoic acid;synthesis;amination;Sandmeyer reaction
研究领域:
有机化学
·
药物化学
✓ 已验证
DOI
IRANIAN POLYMER JOURNAL
·
2016
·Vol. 25
·期 5
·465-474
·
IF 1.684
Zhang Heng,Gao Xin,Chen Ke-Li,Liu Qi-Xing
Parenchyma cellulose, isolated from bagasse pith BP, was utilized as an alternative resource for preparation of soluble cellouronic acid sodium salt (SCA) by selective oxidation with the catalytic amounts of 4-acetamide-TEMPO and NaClO, in which NaClO 2 was used as a primary oxidant in an aqueous condition. The yield and carboxyl content of SCA were measured as a function of NaClO 2 content, 4-acetamide-TEMPO loading, oxidation temperature, initial pH, and reaction time, and optimized by an orthogonal test with the objective of achieving a maximum yield with high carboxyl content. An optimal SCA yield of 71.0 % with 32.92 % carboxyl content was found under the conditions of NaClO 2 dosage of 16 mmol/g, 4-acetamide-TEMPO loading of 0.20 mmol/g, and oxidation temperature of 50 °C in acetate buffer at pH 5.5 for 72 h. The structure and morphology of both parenchyma cellulose and its oxidized product were further characterized by means of Fourier transform infrared spectroscopy (FTIR), X-ray photoelectronic spectroscopy (XPS), X-ray diffraction (XRD), and scanning electron microscopy (SEM). These techniques confirmed that parenchyma cellulose from bagasse pith was successively modified by an effective TEMPO-derivative-catalyzed oxidation process. The finding of this study might provide guidance in maximizing the yield of SCA from parenchyma cells utilizing the 4-acetamide-TEMPO/NaClO/NaClO 2 system. Considering the simple preparation process and favorable SCA property, this BP parenchyma cellulose showed unique characteristics with a great promise for high-valued modification and application in the areas of advanced and functional materials.
研究领域:
生物质转化
·
高分子化学
·
材料科学
·
绿色化学
·
纤维素化学
·
功能材料
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）