Lotus(Nelumbo nucifera),an ancient aquatic plant,possesses a unique pharmacological activity that is primarily contributed by benzylisoquinoline alkaloids(BIAs).However,only few genes and enzymes involved in BIA biosy...Lotus(Nelumbo nucifera),an ancient aquatic plant,possesses a unique pharmacological activity that is primarily contributed by benzylisoquinoline alkaloids(BIAs).However,only few genes and enzymes involved in BIA biosynthesis in N.nucifera have been isolated and characterized.In the present study we identified the regiopromiscuity of an O-methyltransferase,designated NnOMT6,isolated from N.nucifera;NnOMT6 was found to catalyze the methylation of monobenzylisoquinoline 6-O/7-O,aporphine skeleton 6-O,phenylpropanoid 3-O,and protoberberine 2-O.We further probed the key residues affecting NnOMT6 activity via molecular docking and molecular dynamics simulation.Verification using site-directed mutagenesis revealed that residues D316,N130,L135,N176A,D269,and E328 were critical for BIA O-methyltransferase activities;furthermore,N323A,a mutant of NnOMT6,demonstrated a substantial increase in catalytic efficiency for BIAs and a broader acceptor scope compared with wild-type NnOMT6.To the best of our knowledge,this is the first study to report the O-methyltransferase activity of an aporphine skeleton without benzyl moiety substitutions in N.nucifera.The study findings provide biocatalysts for the semisynthesis of related medical compounds and give insights into protein engineering to strengthen O-methyltransferase activity in plants.展开更多
The selective aerobic oxidation of benzyl alcohol to benzaldehyde has attracted considerable attention because benzaldehyde is a high value-added product. The rate of this typical gas–liquid reaction is significantly...The selective aerobic oxidation of benzyl alcohol to benzaldehyde has attracted considerable attention because benzaldehyde is a high value-added product. The rate of this typical gas–liquid reaction is significantly affected by mass transfer. In this study, CoTPP-mediated(CoTPP: cobalt(II) mesotetraphenylporphyrin) selective benzyl alcohol oxidation with oxygen was conducted in a membrane microchannel(MMC) reactor and a bubble column(BC) reactor, respectively. We observed that 83% benzyl alcohol was converted within 6.5 min in the MMC reactor, but only less than 10% benzyl alcohol was converted in the BC reactor. Hydrodynamic characteristics and gas–liquid mass transfer performances were compared for the MMC and BC reactors. The MMC reactor was assumed to be a plug flow reactor,and the dimensionless variance was 0.29. Compared to the BC reactor, the gas–liquid mass transfer was intensified significantly in MMC reactor. It could be ascribed to the high gas holdup(2.9 times higher than that of BC reactor), liquid film mass transfer coefficient(8.2 times higher than that of BC reactor), and mass transfer coefficient per unit interfacial area(3.8 times higher than that of BC reactor). Moreover,the Hatta number for the MMC reactor reached up to 0.61, which was about 15 times higher than that of the BC reactor. The computational fluid dynamics calculations for mass fractions in both liquid and gas phases were consistent with the experimental data.展开更多
Ag-based nanocatalysts exhibit good catalytic activity for the electrochemical reduction of organic halides. Ag-Ni alloy nanoparticles（NPs） were facilely prepared by chemical reduction, and the as-prepared nanocatal...Ag-based nanocatalysts exhibit good catalytic activity for the electrochemical reduction of organic halides. Ag-Ni alloy nanoparticles（NPs） were facilely prepared by chemical reduction, and the as-prepared nanocatalysts were characterized by X-ray diffraction, ultraviolet-visible spectroscopy, transmission electron microscopy and energy-dispersive X-ray spectroscopy. The electrocatalytic activity of Ag-Ni NPs for benzyl chloride reduction was studied in organic medium using cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy. The results show that the addition of Ni element can obviously decrease the size of Ag-Ni NPs, shift the reduction peak potential（φp） of benzyl chloride positively, and increase the catalytic activity of Ag-Ni NPs. However, when the Ni content reaches a certain value, the catalytic activity of Ag-Ni NPs decreases. Meanwhile, the synergistic catalytic effect of Ag-Ni NPs was also discussed.展开更多
The interfacial chemistry of solid electrolyte interphases(SEI)on lithium(Li)electrode is directly determined by the structural chemistry of the electric double layer(EDL)at the interface.Herein,a strategy for regulat...The interfacial chemistry of solid electrolyte interphases(SEI)on lithium(Li)electrode is directly determined by the structural chemistry of the electric double layer(EDL)at the interface.Herein,a strategy for regulating the structural chemistry of EDL via the introduction of intermolecular hydrogen bonds has been proposed(p-hydroxybenzoic acid(pHA)is selected as proof-of-concept).According to the molecular dynamics(MD)simulation and density functional theory(DFT)calculation results,the existence of hydrogen bonds realizes the anion structural rearrangement in the EDL,reduces the lowest unoccupied molecular orbital(LUMO)energy level of anions in the EDL,and the number of free solvent molecules,which promotes the formation of inorganic species-enriched SEI and eventually achieves the dendrite-free Li deposition.Based on this strategy,Li‖Cu cells can stably run over 185 cycles with an accumulated active Li loss of only 2.27 mAh cm^(-2),and the long-term cycle stability of Li‖Li cells is increased to 1200 h.In addition,the full cell pairing with the commercial LiFePO_(4)(LFP)cathodes exhibits stable cycling performance at 1C,with a capacity retention close to 90%after 200 cycles.展开更多
基金supported by the National Natural Science Foundation of China(32170388)the Scientific and Technological Innovation project of China Academy of Chinese Medical Sciences(CACMS Innovation Fund CI2021A04108,CI2021A04515)the Fundamental Research Funds for the Central Public Welfare Research Institutes of China(ZZ13-YQ-057,ZXKT21006)。
文摘Lotus(Nelumbo nucifera),an ancient aquatic plant,possesses a unique pharmacological activity that is primarily contributed by benzylisoquinoline alkaloids(BIAs).However,only few genes and enzymes involved in BIA biosynthesis in N.nucifera have been isolated and characterized.In the present study we identified the regiopromiscuity of an O-methyltransferase,designated NnOMT6,isolated from N.nucifera;NnOMT6 was found to catalyze the methylation of monobenzylisoquinoline 6-O/7-O,aporphine skeleton 6-O,phenylpropanoid 3-O,and protoberberine 2-O.We further probed the key residues affecting NnOMT6 activity via molecular docking and molecular dynamics simulation.Verification using site-directed mutagenesis revealed that residues D316,N130,L135,N176A,D269,and E328 were critical for BIA O-methyltransferase activities;furthermore,N323A,a mutant of NnOMT6,demonstrated a substantial increase in catalytic efficiency for BIAs and a broader acceptor scope compared with wild-type NnOMT6.To the best of our knowledge,this is the first study to report the O-methyltransferase activity of an aporphine skeleton without benzyl moiety substitutions in N.nucifera.The study findings provide biocatalysts for the semisynthesis of related medical compounds and give insights into protein engineering to strengthen O-methyltransferase activity in plants.
基金financially supported by the National Key Research and Development Program of China (2020YFA0210900)the National Natural Science Foundation of China (21938001 and 21878344)+1 种基金Guangdong Provincial Key Research and Development Programme (2019B110206002)the Local Innovative and Research Teams Project of Guangdong Pearl River Talents Program (2017BT01C102)。
文摘The selective aerobic oxidation of benzyl alcohol to benzaldehyde has attracted considerable attention because benzaldehyde is a high value-added product. The rate of this typical gas–liquid reaction is significantly affected by mass transfer. In this study, CoTPP-mediated(CoTPP: cobalt(II) mesotetraphenylporphyrin) selective benzyl alcohol oxidation with oxygen was conducted in a membrane microchannel(MMC) reactor and a bubble column(BC) reactor, respectively. We observed that 83% benzyl alcohol was converted within 6.5 min in the MMC reactor, but only less than 10% benzyl alcohol was converted in the BC reactor. Hydrodynamic characteristics and gas–liquid mass transfer performances were compared for the MMC and BC reactors. The MMC reactor was assumed to be a plug flow reactor,and the dimensionless variance was 0.29. Compared to the BC reactor, the gas–liquid mass transfer was intensified significantly in MMC reactor. It could be ascribed to the high gas holdup(2.9 times higher than that of BC reactor), liquid film mass transfer coefficient(8.2 times higher than that of BC reactor), and mass transfer coefficient per unit interfacial area(3.8 times higher than that of BC reactor). Moreover,the Hatta number for the MMC reactor reached up to 0.61, which was about 15 times higher than that of the BC reactor. The computational fluid dynamics calculations for mass fractions in both liquid and gas phases were consistent with the experimental data.
基金Projects(2127106951238002+3 种基金J1210040J1103312)supported by the National Natural Science Foundation of ChinaProject(2013GK3015)supported by the Science and Technology Project of Hunan ProvinceChina
文摘Ag-based nanocatalysts exhibit good catalytic activity for the electrochemical reduction of organic halides. Ag-Ni alloy nanoparticles（NPs） were facilely prepared by chemical reduction, and the as-prepared nanocatalysts were characterized by X-ray diffraction, ultraviolet-visible spectroscopy, transmission electron microscopy and energy-dispersive X-ray spectroscopy. The electrocatalytic activity of Ag-Ni NPs for benzyl chloride reduction was studied in organic medium using cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy. The results show that the addition of Ni element can obviously decrease the size of Ag-Ni NPs, shift the reduction peak potential（φp） of benzyl chloride positively, and increase the catalytic activity of Ag-Ni NPs. However, when the Ni content reaches a certain value, the catalytic activity of Ag-Ni NPs decreases. Meanwhile, the synergistic catalytic effect of Ag-Ni NPs was also discussed.
基金financially supported by the National Natural Science Foundation of China(Grant No.21905033,52271201)the Key Research and DevelopmentProgram of Sichuan Province(Grant No.2022YFG0100)+1 种基金the Central Government Funds of Guiding Local Scientific and Technological Development for Sichuan Province(Grant No.2022ZYD0045)the State Key Laboratory of Vanadium and Titanium Resources Comprehensive Utilization(Grant No.2020P4FZG02A)
文摘The interfacial chemistry of solid electrolyte interphases(SEI)on lithium(Li)electrode is directly determined by the structural chemistry of the electric double layer(EDL)at the interface.Herein,a strategy for regulating the structural chemistry of EDL via the introduction of intermolecular hydrogen bonds has been proposed(p-hydroxybenzoic acid(pHA)is selected as proof-of-concept).According to the molecular dynamics(MD)simulation and density functional theory(DFT)calculation results,the existence of hydrogen bonds realizes the anion structural rearrangement in the EDL,reduces the lowest unoccupied molecular orbital(LUMO)energy level of anions in the EDL,and the number of free solvent molecules,which promotes the formation of inorganic species-enriched SEI and eventually achieves the dendrite-free Li deposition.Based on this strategy,Li‖Cu cells can stably run over 185 cycles with an accumulated active Li loss of only 2.27 mAh cm^(-2),and the long-term cycle stability of Li‖Li cells is increased to 1200 h.In addition,the full cell pairing with the commercial LiFePO_(4)(LFP)cathodes exhibits stable cycling performance at 1C,with a capacity retention close to 90%after 200 cycles.
