INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
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2019
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IF 4.784
Xiaoxiao Li,Yuxiang Bai,Hangyan Ji,Jinpeng Wang,Yinglu Cui,Zhengyu Jin
Pullulanase, a typical debranching enzyme, specifically hydrolyzes α-1,6 glycosidic linkages in pullulan, starch and so on. There is accumulated knowledge about the catalysis of pullulanase, but functional roles of acceptor subsites get less attention. According to the crystal structure of pullulanase from Bacillus subtilis str. 168, stacking interaction between tryptophan437 and glycosyl unit of α-CD was found. Trp437 located in conserved region III was highly conserved in pullulanases. But functional role of this residue remains unclear. Site-directed mutagenesis was used to determine the function of Trp437. Replacement of Trp437 with glycine, phenylalanine, proline, arginine resulted in mutants with undetectable hydrolysis activity and reverse hydrolysis activity. The secondary structure of mutated proteins showed no difference from the wild-type pullulanase, but they lost the capability to bind β-CD based on the ITC measurement. Molecular docking was performed to investigate the affinity of proteins to ligands including maltotriose, 6 2 -α-D-maltotriosyl-maltotriose and α-CD, showing the affinity of mutants to ligands became weaker compared to that of PulA. And the hydrogen bond between Trp437 and Glu525 in PulA only was found in mutant W437R. These results show that Trp437 at subsite +2 plays crucial role in catalysis of PulA, and it has little tolerance to change.
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LANGMUIR
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2019
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IF 3.683
Binbin Wan,Junying Li,Feng Ma,Ning Yu,Wenjing Zhang,Lujie Jiang,Hengshan Wei
The immobilized metal affinity cryogels based on poly(2-hydroxyethyl methacrylate-co-glycidyl methacrylate) (p(HEMA-GMA)) containing hydroxy and epoxy groups were prepared by free-radical copolymerization under cryogenic condition and then functionalized with iminodiacetic acid and chelated Cu2+, Ca2+, and Fe3+ ions to the p(HEMA-GMA) cryogel. The structures of p(HEMA-GMA) and immobilized metal-affinity cryogels were analyzed by Fourier transform infrared spectroscopy and scanning electron microscopy (SEM)–energy dispersive X-ray spectroscopy. SEM results showed that the prepared cryogels had interconnected pores with the size of 30–100 μm. The performance of water swelling into the cryogels was fitted in Fickian diffusion. The adsorption property of cryogels was influenced by the immobilized ionic type, temperature, and adsorbate. The adsorption capacity of immobilized Cu2+ cryogel (p(HEMA)–Cu2+ (0.5 M) cryogel) was the highest in comparison with that of Ca2+ and Fe3+ affinity cryogels under the same condition. The maximum adsorption capacity of p(HEMA)–Cu2+ (0.5 M) cryogel for porcine pancreatic lipase was 150.14 mg/g at a higher temperature of 35 °C, whereas for bovine serum albumin, the maximum adsorption capacity was 154.11 mg/g at a lower temperature of 25 °C. The research of thermodynamics and kinetics indicated that the mechanism of the protein adsorption process corresponded to the Langmuir model and pseudo-second-order model.
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EUROPEAN JOURNAL OF PHARMACOLOGY
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2019
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IF 3.17
Hui Li,Siyi Pan,Xiaoyun Xu
Flavonoids are natural active components. They distribute widely in edible plants with high activity of anti-inflammation. Inhibition of cyclooxygenase-2(COX-2) was determined by real-time fluorescent quantitative olymerase chain reaction (RTFQ-PCR). And structure characteristics of flavonoids for COX-2 inhibition were mainly analyzed by a quantitative structure activity relationship (QSAR) model. Descriptors such as SMR_VSA5, vsurf_DD12, reactive were the top three important independent variables to COX-2 mRNA inhibiton in RAW264.7. Low SMR_VSA5 value meant a lower molecular refractivity resulting in a lower COX-2 mRNA inhibition. High vsurf_DD12 value related to poor molecular balance and showed profound adverse to COX-2 mRNA inhibition. Reactive group in this paper referred to C2–C3 double bond contributed negatively to COX-2 mRNA inhibition. Glycosidic and C3–OH substitutions may lower SMR_VSA5 value. It indicated that flavanones such as hesperetin , naringenin , liquiritigenin were efficient to repress COX-2 mRNA and they were potential anti-inflammatory natural products. Further, substitution with a glucopyranosyl at C-6 resulted in a poorer molecule balance than that at C-8 and a lower COX-2 mRNA inhibiton accordingly. This may expain why orientin and vitexin exhibited better anti-inflammatory activity than their isomers homoorientin and isovitexin . Also, methoxyl groups at C-4’ may also be a favorable flavonoid structural characteristic for COX-2 mRNA inhibiton. These results provide valuable information on understanding the high anti-inflammatory activity of flavonoids.
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JOURNAL OF MOLECULAR LIQUIDS
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2019
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IF 4.561
Yajun Li,Kui Wu,Lei Liang
The solid-liquid equilibrium solubility of 2-phenylacetamide in sixteen pure solvents, i.e. methanol, ethanol, n -propanol, isopropanol, n -butanol, isobutanol , n -pentanol, isopentanol, acetone, ethyl acetate , acetonitrile , 2-butanone, 2-pentanone, methyl acetate , ethyl formate and tetrahydrofuran was obtained over a temperature range from 273.75 K to 324.95 K by a gravimetric method under atmospheric pressure. For all the solvents investigated, the equilibrium solubility of 2-phenylacetamide increases with augmented temperature. The statistical correlations were correlated by the modified Apelblat model, λh equation, non-random two-liquid (NRTL) equation and the Wilson equation. On the basis of thermodynamic relations and the Wilson model, the dissolution enthalpy, entropy, and Gibbs free energy were calculated. The results demonstrate that the dissolution of 2-phenylacetamide is a spontaneous and entropy-driven process in the selected solvents. The solubility data, correlation models and derived dissolution properties would promote the development of the separation and reaction of 2-phenylacetamide in industry.
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JOURNAL OF LUMINESCENCE
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2019
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IF 2.961
Yan Hua,Daocheng Hong,Sushu Wan,Yanyu Lei,Mingcai Xie,Weiqing Yang,Yu Du,Yuxi Tian
2D perovskite materials have attracted increasing attention in the last few years due to their optical tunability. However, how to control the structure of these materials is still one of the key challenges. In this work, by using photoluminescence microscopy and XRD characterization, we found that ethanol treatment can induce the reorganization of the crystal structure of 2D perovskite materials. The ethanol molecules can insert into (OA) 2 (MA)Pb 2 I 7 (OA = CH 3 (CH 2 ) 7 NH 3 ; MA = CH 3 NH 3 ) crystal lattice and preferentially dissolve MA ions reducing the MA/OA ratio. During the recrystallization, new (OA) 2 PbI 4 phase forms due to the low MA/OA ratio. On the other hand, adsorption of ethanol can induce the photoluminescence (PL) enhancement by passivation of the surface defects . Consequently, PL intensity increases and decreases as the activation/deactivation of the quenching defects. These results provide a possible way to optimize the crystal structure of 2D perovskite under mild condition.
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CHIRALITY
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2019
·Vol. 32
·期 2
·231-238
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IF 1.927
Peng Wu,Mengjie Zhang,Yinjun Zhang,Zhao Wang,Jianyong Zheng
In this study, a novel lipase M5 derived from Aspergillus oryzae WZ007 was prone to exhibit high hydrolytic activity and stereoselectivity towards racemic substrate ( R , S )-ethyl 2-bromoisovalerate. ( R )-ethyl 2-bromoisovalerate was obtained by enzymatic resolution, which is the key chiral intermediate for highly efficient enantiomerically fluvalinate. The results showed that the enzymatic reaction was carried out in 120mM racemic substrate for 3 hours, the enantiomeric excess reached 98.6%, the conversion was 51.7%, and E value above 120. Therefore, the novel lipase M5 has the ability to efficiently produce ( R )-ethyl 2-bromoisovalerate, which greatly reduces the industrial production cost of the highly efficient counterpart of fluvalinate.
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JOURNAL OF MOLECULAR LIQUIDS
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2019
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IF 4.561
Hongxin Bai,Xiangchen Fang,Chong Peng,Quanjie Liu,Weibin Xie,Liming Jia,Zhaoyang Song
Alkylated anthraquinone is widely used as promising redox-active materials for both redox flow batteries technology and hydrogen peroxide production via anthraquinone oxidation (AO) process, yet its inadequate solubility in solvents has been the one of the main limitations resulting to insufficient energy density of working solution. In present study, solubility of 2-ethylanthraquinone was specifically investigated by the synthetic method at the temperature range from 304.15 to 344.15 K under the pressure of 101.325 kPa. In support for decent working solution exploit, various types of solvents were specifically selected as the working solution constituent in this work. Solubility data and activity coefficient of 2-ethylanthraquinone were correlated by modified Apelblat and λ-h models. Furthermore, thermodynamic analysis was subsequently performed based on the thermodynamic fitting results. As a result, dissolution process of 2-ethylanthraquinone is endothermic and entropy-driven in these neat solvents, higher dissolution temperature leads to smaller value of partial molar excess Gibbs free energy and therefore results to a greater solubility.
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Scientific Reports
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2019
·Vol. 9
·期 1
·1-10
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IF 4.011
Chen Jian,Wang Zhen,Li Yupeng,Feng Chunmu,Dai Jianhui,Xu Zhu’an,Si Qimiao
We study the quantum phase transitions in the nickel pnctides, CeNi 2− δ (As 1− x P x ) 2 ( δ ≈ 0.07–0.22) polycrystalline samples. This series displays the distinct heavy fermion behavior in the rarely studied parameter regime of dilute carrier limit. We systematically investigate the magnetization, specific heat and electrical transport down to low temperatures. Upon increasing the P-content, the antiferromagnetic order of the Ce-4 f moment is suppressed continuously and vanishes at x c ~ 0.55. At this doping, the temperature dependences of the specific heat and longitudinal resistivity display non-Fermi liquid behavior. Both the residual resistivity ρ 0 and the Sommerfeld coefficient γ 0 are sharply peaked around x c . When the P-content reaches close to 100%, we observe a clear low-temperature crossover into the Fermi liquid regime. In contrast to what happens in the parent compound x = 0.0 as a function of pressure, we find a surprising result that the non-Fermi liquid behavior persists over a nonzero range of doping concentration, x c < x < 0.9. In this doping range, at the lowest measured temperatures, the temperature dependence of the specific-heat coefficient is logarithmically divergent and that of the electrical resistivity is linear. We discuss the properties of CeNi 2− δ (As 1− x P x ) 2 in comparison with those of its 1111 counterpart, CeNi(As 1− x P x )O. Our results indicate a non-Fermi liquid phase in the global phase diagram of heavy fermion metals.
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COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
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2018
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IF 2.829
Yanjun Liu,Ping Na,Jitao Chen,Yulong Xie
K 2 Zn 3 [Fe(CN) 6 ] 2 @ Ni-P (KNiP) composites with high cesium selectivity were synthesized for the first time. Nickel phosphorus (NiP) was used as a solid base for the adsorption of K 2 Zn 3 [Fe(CN) 6 ] 2 (KZnHCF). The synthesized KNiP composites were characterized by SEM, TEM, XRD , VSM and BET. The characteristic results demonstrated that the composites possess a ball-shape structure, a large surface area of 305.031 m 2 /g and high saturation magnetization of 2.95 emu/g. The ICP-OES analyser was used to determine the concentration of ions in this study. KNiP showed good cesium adsorption performance over a wide pH range and high selectivity for cesium over coexistent competing ions. Analysis of dynamics showed that KNiP has good adsorption performance toward cesium, with an adsorption capacity of 54.95 mg/g. Equilibrium was achieved within only two hours and the experimental data fit the Pseudo second-order model, indicating that the adsorption process was chemisorption . The adsorption process followed the Freundlich isotherm model, indicating that it mainly occured on a heterogeneous surface.
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Energy Technology
·
2018
·Vol. 7
·期 3
·1800476
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IF 3.175
Zimin Jiang,Tingting Xu,Shuge Dai,Congcong Yan,Caiyun Ma,Xinchang Wang,Junmin Xu,Sen Zhang,Ye Wang
3D Ni(OH) 2 /tungsten disulfide (WS 2 ) nanofibers composed of ultrathin nanoflakes are synthesized by electrospinning followed by a hydrothermal process, which have a large specific surface of 64.56 m 2 g −1 . When tested in a three-electrode configuration, the WS 2 /Ni(OH) 2 nanofiber-based electrode exhibits a high specific capacity of 354 C g −1 at a current density of 1 A g −1 . The hybrid storage device, in which WS 2 /Ni(OH) 2 nanofibers and graphene are used as the positive and negative electrodes, respectively, exhibits a high energy density of 34 Wh kg −1 at a power density of 940 W kg −1 and a high capacity retention of 83% after 4000 cycles at 4 A g −1 . The as-synthesized 3D Ni(OH) 2 /WS 2 nanofibers provide a way for the WS 2 nanostructure to optimize its viability and potential in constructing a high-performance energy storage device.
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BIOPROCESS AND BIOSYSTEMS ENGINEERING
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2019
·Vol. 42
·期 10
·1573-1582
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IF 2.371
Zhou Hai-Yan,Li Yi-Zuo,Jiang Rui,Hu Hai-Feng,Wang Yuan-Shan,Liu Zhi-Qiang,Xue Ya-Ping,Zheng Yu-Guo
R -2-(4-hydroxyphenoxy)propionic acid ( R -HPPA) is a key intermediate of the enantiomerically pure phenoxypropionic acid herbicides. R -HPPA could be biosynthesized through selective introduction of a hydroxyl group (–OH) into the substrate R -2-phenoxypropionic acid ( R -PPA) at C-4 position, facilitated by microorganisms with hydroxylases. In this study, an efficient high-throughput screening method for improved R -HPPA biosynthesis through microbial hydroxylation was developed. As a hydroxylated aromatic product, R -HPPA could be oxidized by oxidant potassium dichromate to form brown-colored quinone-type compound. The concentration of R -HPPA can be quantified according to the absorbance of the colored compound at a suitable wavelength of 570 nm; and the R -HPPA biosynthetic capability of microorganism strains could also be rapidly evaluated. After optimization of the assay conditions, the high-throughput screening method was successfully used in identification of Beauveria bassiana mutants with enhanced R -HPPA biosynthesis capacity. A positive mutant C-7 with high tolerance to 20 g/L R -PPA was rapidly selected from 1920 mutants. The biomass and R -HPPA titer were 12.5- and 38.19-fold higher compared with the original strain at 20 g/L R -PPA. This high-throughput screening method developed in this work could also be a potential tool for screening strains producing other important phenolic compounds.
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JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY
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2018
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IF 3.412
Jinbin Liu,Jing Jiang,Yajun Bai,Tai-ping Fan,Ye Zhao,Xiaohui Zheng,Yujie Cai
Bacteria rarely produce natural 2-phenylethanol. We verified a new pathway from Proteus mirabilis JN458 to produce 2-phenylethanol using Escherichia coli to coexpress l-amino acid deaminase, α-keto acid decarboxylase, and alcohol dehydrogenase from P. mirabilis. Based on this pathway, a glucose dehydrogenase coenzyme regeneration system was constructed. The optimal conditions of biotransformation by the recombinant strain E-pAEAKaG were at 40 °C and pH 7.0. Finally, the recombinant strain E-pAEAKaG produced 3.21 ± 0.10 g/L 2-phenylethanol in M9 medium containing 10 g/L l-phenylalanine after a 16 h transformation. Furthermore, when the concentration of l-phenylalanine was 4 g/L (24 mM), the production of 2-phenylethanol reached 2.88 ± 0.18 g/L and displayed a higher conversion rate of 97.38 mol %.
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