Organic acid content is one of the most important factors influencing fruit flavors.The predominant organic acid in most pear cultivars is malic acid,but the mechanism controlling its accumulation remains unclear.In t...Organic acid content is one of the most important factors influencing fruit flavors.The predominant organic acid in most pear cultivars is malic acid,but the mechanism controlling its accumulation remains unclear.In this study,by comparing gene expression levels and organic acid contents,we found that the expression of PbPH5,which encodes a P_(3A)-ATPase,is highly correlated with malic acid accumulation in four different pear species,with correlation coefficients of 0.932**,0.656*,0.900**,and 0.518*(*,P<0.05;**,P<0.01)for Pyrus bretschneideri Rehd.,P.communis Linn.,P.pyrifolia Nakai.,and P.ussuriensis Maxim.,respectively.Moreover,the overexpression of PbPH5 in pear significantly increased the malic acid content.In contrast,silencing PbPH5 via RNA interference significantly decreased both its transcript level and the pear fruit malic acid content.A subcellular localization analysis indicated that PbPH5 is located in the tonoplast.Additionally,a phylogenetic analysis indicated that PbPH5 is a PH5 homolog gene that is clustered with the Petunia hybrida,Malus domestica,and Citrus reticulata genes.Considered together,these findings suggest that PbPH5 is a functionally conserved gene.Furthermore,the accumulation of malic acid in pear fruit is at least partly related to changes in the PbPH5 transcription levels.展开更多
A novel kinetic method for determination of trace amounts of cobalt ion was proposed and validated. The method is based on adding malic acid into classical Belousov-Zhabotinskii （B-Z） oscillating chemical system to ...A novel kinetic method for determination of trace amounts of cobalt ion was proposed and validated. The method is based on adding malic acid into classical Belousov-Zhabotinskii （B-Z） oscillating chemical system to form a double substrate one. The results showed that when the concentration of cobalt ion was in the range of 5.27× 10^-8 to 5.37 × 10^-12 mol L^-1, the change of the oscillating period was directly proportional to the negative logarithm of cobalt ion concentration. The sensitivity and precision of the developed method were quite satisfactory. The limit of detection was down to 5.20 × 10^-13 mol L^-1 which was a highest sensitivity found for determination of metal ions using oscillating chemical reaction so far. Some factors influencing the determination were also examined. The method has been successfully used to determine cobalt ion in vitamin B12 injection.展开更多
A synthesis of methyl 2-hydroxy-4-oxo-4-（substituted phenyl）butanoates has been accomplished using Friedel-Crafts acylation of substituted benzenes with 2-acetoxybutanoyl chloride. The key feature of this strategy i...A synthesis of methyl 2-hydroxy-4-oxo-4-（substituted phenyl）butanoates has been accomplished using Friedel-Crafts acylation of substituted benzenes with 2-acetoxybutanoyl chloride. The key feature of this strategy is that various 4-arylbutanoates can be obtained conveniently, which are important intermediates for the synthesis of biologically active compounds including ACE inhibitors.？2009 Yong Sup Lee. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.展开更多
Ammonium tetramolybdate ( NH4 )4[(MoO2)4O3 (R-mal)2]·6H2O(mal= malic acid)and (NH4)4[(MoO2)4O3(S-mal)2)·6H2O have been prepared by the reaction of R and S-malic acid with ammonium heptamolybdate, respectivel...Ammonium tetramolybdate ( NH4 )4[(MoO2)4O3 (R-mal)2]·6H2O(mal= malic acid)and (NH4)4[(MoO2)4O3(S-mal)2)·6H2O have been prepared by the reaction of R and S-malic acid with ammonium heptamolybdate, respectively. The two complexes are enantiomeric and isomorphous. The complex of Risomer crystallizes in monoclinic space group C2 with unit cell parameters:a = 14. 591 (2 ), b = 10. 108(2), c=11. 464(2), β=121. 48(1)°, V=1441. 9(4),Z=2, Fω=1002. 13, Dc=2. 308, Dm=2. 3 g/cm3. F(000) = 988, MoKα radiation (λ=0. 71073 ), μ (MoKα) = 17. 7 cm-1. Final R=0. 027 for 1491 reflections with I>2. 5 σ(I). Analysis of molecular structure reveals that the complex anion contains a (Mo2O5)O(Mo2O5)core with the bridging oxo-group passing through two-fold axis. Each molybdenum is hexacoordinated , and the malate ligand is quadridentated to two molybdenum atoms by the deprotonated hydroxy-, α- and β-carboxylate groups. Principal dimensions are:[Mo=O(t)]av, 1. 705(6); [Mo-O(b)]av, 1. 920(6); Mo-O(hydroxy). 1. 925(6);Mo-O(α-carboxy), 2. 226 (6), and [Mo-O(β-carboxy)av, 2. 296 (5).Lattice water is distributed throughout the cell and together with various types of the anion oxygens, making H-bonding.展开更多
Terpolymer of 1, 8-octanediol, adipic acid, and L-malic acid was synthesized via a lipase-catalyzed direct polycondensation. The products were characterized by GPC and 1H NMR. The results indicated that the molecular ...Terpolymer of 1, 8-octanediol, adipic acid, and L-malic acid was synthesized via a lipase-catalyzed direct polycondensation. The products were characterized by GPC and 1H NMR. The results indicated that the molecular weight of the prepared polymers decreased with increasing L-malic acid content in the monomer feed ratio, and that change in the L-malic acid content from 0 to 20 mol % did not remarkably influenced on the molecular weight distribution Mw /Ma of the prepared samples. The 1H NMR spectra of the obtained copolymer samples showed that hydroxyl groups of L-malic acid did not take part in the polymerization reaction.展开更多
In order to create a functionalized biodegradable polymer for vascular tissue engineering application,poly(DL- lactide-co-RS-β-malic acid)(PDLLMAc)was synthesized.PDLLMAc was obtained after hydrogenolysis of poly(DL-...In order to create a functionalized biodegradable polymer for vascular tissue engineering application,poly(DL- lactide-co-RS-β-malic acid)(PDLLMAc)was synthesized.PDLLMAc was obtained after hydrogenolysis of poly(DL- lactide-co-RS-β-benzyl malolactonate)(PDLLMA),which was from the ring-opening polymerization of DL-lactide(DLLA) and RS-β-benzyl malolactonate(MA)using stannous octoate as catalyst.The copolymers were characterized by ~1H-NMR, FTIR,GPC and DSC.The tensile strength and water uptake of the copoly...展开更多
The effect of some phenolic compounds recurrent in wines on technological features of Oenococcus oeni was studied in order to individuate those strains to be utilized as starter in the deacidification of aged red wine...The effect of some phenolic compounds recurrent in wines on technological features of Oenococcus oeni was studied in order to individuate those strains to be utilized as starter in the deacidification of aged red wines. For this purpose, the growth and the L-malic acid metabolism of 100O. oeni strains, previously isolated from different wines, was assayed in a synthetic medium added with ethanol, malic acid and phenol carboxylic （gallic, caffeic, p-coumaric and ferulic） acids or flavonoids （catechin and quercetin） at different concentrations. Results evidenced a different sensitivity of strains to each assayed compound. All the compounds restrained or stimulated the growth of 57 and 11 strains respectively, while no effect was detected on 6 strains. The remaining 26 strains showed a different behaviour： all were restrained by ferulic acid and stimulated by gallic acid and catechin. As for caffeic acid, 17 out of 26 strains were restrained, while 9 strains were stimulated. The main result obtained in this study was the establishment of a relationship between the effect of phenolic compounds on the O. oeni growth and the behaviour of the malolactic fermentation. This study may enrich the selection criteria of strains for the deacidification of aged red wines.展开更多
The catalyst preparation strategy was based on a strict introduction sequence of rhenium and platinum precursors and their strong interaction with carbon support resulted in the formation of 0.5 nm Pt-Re Ox species of...The catalyst preparation strategy was based on a strict introduction sequence of rhenium and platinum precursors and their strong interaction with carbon support resulted in the formation of 0.5 nm Pt-Re Ox species of atomic dispersion, where platinum is metallic, while monolayer rhenium is partially oxidized（Re2＋）. The reaction kinetics was studied taking into account the process of L-malic acid association leading to the formation of inactive cyclic oligomeric species. High TOFs（ca. 50 h-1）, selectivities（ca. 99%）and stability of Pt-Re Ox/C catalysts in aqueous-phase hydrogenation of L-malic acid, which are close to those of the homogeneous pincer type complexes, were revealed at mild conditions（T = 90–130 ℃）. Taking into account that（i） hydrogenation reaction occurred 2–3 orders of magnitude faster than its racemization and（ii） association of L-malic acid dominates at low temperatures and in a concentrated solution,special reaction conditions that allow obtaining chemically and optically（ee 〉 99%） pure（S）-3-hydroxy-γ-butyrolactone and（S）-1,2,4-butanetriol were found. Basing on HAADF-STEM, EDX, XPS, and kinetic studies, the structure of active species and basic reaction pathways are proposed.展开更多
Background Intestinal oxidative stress serves as an endogenous host defense against the gut microbiota by increas-ing energy expenditure and therefore decreasing feed efficiency(FE).Several systems coordinately regula...Background Intestinal oxidative stress serves as an endogenous host defense against the gut microbiota by increas-ing energy expenditure and therefore decreasing feed efficiency(FE).Several systems coordinately regulate redox bal-ance,including the mitochondrial respiratory chain,nicotinamide adenine dinucleotide phosphate(NADPH)oxidase,and different antioxidants.However,it remains unclear which redox balance compartments in the intestine are crucial for determining FE.Results In this study,we first screened the key targets of different metabolites and redox balance-related gene expression in broiler ceca.We then constructed a mouse colitis model to explore malic acid(MA)ability to allevi-ate intestinal inflammation.We further used controlled release technology to coat MA and investigated its effects on the intestinal redox status and FE in vivo.Finally,we examined the underlying mechanism by which MA modulated redox status using a porcine intestinal epithelial cell jejunum 2(IPEC-J2)cell model in vitro.Our results demonstrated that the MA/malic enzyme 3(ME3)pathway may play an important role in reducing oxidative stress in the broiler cecum.In addition,colon infusion of MA attenuated inflammatory phenotypes in the dextran sulfate sodium salt(DSS)induced mouse colitis model.Then,dietary supplementation with controlled-release MA pellet(MAP)reduced the feed to gain(F/G)ratio and promoted chicken growth,with reduced oxidative stress and increased bacterial diver-sity.Finally,the in vitro IPEC-J2 cell model revealed that ME3 mediated the effect of MA on cellular oxidative stress.Conclusion In summary,our study firstly revealed the important role of the MA/ME3 system in the hindgut of broiler chickens for improving intestinal health and FE,which may also be crucial for the implications of colon inflammation associated diseases.展开更多
A dimeric Y(III)-containing antimonotungstate[Y_(4)(H_(2)O)_(8)(mal)_(2)(OAc)O(Sb_(2)W_(2)^(V)W_(19)^(VI)O_(72))_(2)]^(21-)(Y_(4)mal_(2),H_(3)mal=DL-malic acid),resembling a“handshake”configuration,was synthesized a...A dimeric Y(III)-containing antimonotungstate[Y_(4)(H_(2)O)_(8)(mal)_(2)(OAc)O(Sb_(2)W_(2)^(V)W_(19)^(VI)O_(72))_(2)]^(21-)(Y_(4)mal_(2),H_(3)mal=DL-malic acid),resembling a“handshake”configuration,was synthesized and characterized.The polyanion of Y_(4)mal_(2)consists of two Dawson-derived{Y_(2)Sb_(2)W_(21)}moieties that are further linked by two mal ligands and oneμ_(2)-bridging acetate to form an asymmetric polyanion.Notably,the chiral configuration induced by the D-or L-configuration of the mal ligand results in both{Y_(2)Sb_(2)W_(21)}moieties within one polyanion exhibiting identical chirality,leading to the racemate crystallization of Y_(4)mal_(2).Moreover,Y_(4)mal_(2)exhibits excellent Lewis acid catalytic activity for environmentally friendly synthesis of imidazoles.展开更多
Extraction equilibrium features of succinic acid, malic acid,maleic acid and fumaric acid were investi- gated systematically withtrioctylamine (TOA) in chloroform, 4-methyl-2-pentanone (MIBK) and1-octanol. Fourier tra...Extraction equilibrium features of succinic acid, malic acid,maleic acid and fumaric acid were investi- gated systematically withtrioctylamine (TOA) in chloroform, 4-methyl-2-pentanone (MIBK) and1-octanol. Fourier transform-infrared (FTIR) spectroscopic analysisof organic samples loaded with the acid shows that amine forms 1:1complex of ion-pair association with succinic acid, malic acid andmaleic acid, and 1:1, 2:1 complex of ion-pair association withfumaric acid. It is proposed that the complex forms depend on thesecond dissociation constant of the dibasic acid, pK_a2.展开更多
Crystals of the chiral malic acid hydrate (C_4H_6O_5·H_2O) were unexpectedlyobtained from an ethanol/water solution containing racemic D, L-malic acid and L-asparagine. Thecrystal belongs to orthorhombic space gr...Crystals of the chiral malic acid hydrate (C_4H_6O_5·H_2O) were unexpectedlyobtained from an ethanol/water solution containing racemic D, L-malic acid and L-asparagine. Thecrystal belongs to orthorhombic space group P2_12_12_1 with cell dimensions of a = 0.5576(1), b =0.9818(2), c = 1.1793(2) nm, V = 0.6455(2) nm^3, Z = 4, μ(Mo K_a) =0.152 mm^(-1), F(000) = 320, D_c= 1.565 g·cm^(-3), R=0.051, wR = 0.136 for 657 observed reflections [ I > 2σ(I) ]. Thesignificant difference in bond distances for carboxyl groups suggests that the crystal consist ofmalate anion and protonized crystalline water. This is a report for direct separation of racemicmixture, i.e., without the formation of a molecular complex of raceme with a chiral separatingreagent.展开更多
The protein family of 14-3-3(s) has risen to a position of higher importance as an adaptor protein in cell biology. The seven highly conserved human 14-3-3 proteins coordinate diverse cellular processes including apop...The protein family of 14-3-3(s) has risen to a position of higher importance as an adaptor protein in cell biology. The seven highly conserved human 14-3-3 proteins coordinate diverse cellular processes including apoptosis, DNA damage response, protein trafficking, and others. In liver hepatocytes, 14-3-3β binds to Ser196-phosphorilated glucose-responsive carbohydrate response element-binding protein (ChREBP) to inhibit converting excess carbohydrate to fat by regulating the nuclear/cytosol trafficking of ChREBP. Here, we report X-ray crystal structures of homodimeric mammalian 14-3-3β in its apo, Malate-bound forms. The determined apo structure was captured with one monomer in the closed state, whereas the other one had an open conformation. Strikingly, 14-3-3β binds Malate dynamically with a double-closed state, which is distinct from all previously characterized 14-3-3(s) and target ligand-binding modes. Malate docks into a first-time observed cofactor pocket located at the concaved interface of 14-3-3β helices α2, α3, α4 through mainly electrostatic and hydrogen interactions. Such a Tricarboxylic Acid Cycle intermediate Malate bond model might offer a new approach to further analyze insulin-independent 14-3-3/ChREBP pathway of de novo fat synthesis in the liver.展开更多
为探究不同取代度(Degree of Substitution,DS)对苹果酸大米淀粉酯理化特性及对面条品质的影响,制备不同取代度(DS=0~0.603)苹果酸大米淀粉酯,考察了苹果酸大米淀粉酯溶解度、溶胀度、糊化特性和流变特性,以及对面条蒸煮特性、质构特性...为探究不同取代度(Degree of Substitution,DS)对苹果酸大米淀粉酯理化特性及对面条品质的影响,制备不同取代度(DS=0~0.603)苹果酸大米淀粉酯,考察了苹果酸大米淀粉酯溶解度、溶胀度、糊化特性和流变特性,以及对面条蒸煮特性、质构特性和感官特性的改善作用。结果表明,苹果酸淀粉酯的红外光谱分析显示在光谱波数约1720 cm-1处出现一个新的吸收峰。淀粉发生酯化反应后溶解度显著升高(P<0.05),但溶胀度有所下降。糊化和流变实验结果表明,低酯化淀粉(DS=0.141~0.442)的加入显著降低(P<0.05)了淀粉的峰值黏度,降低了苹果酸淀粉酯的储能模量G′和损耗模量G″,高酯化淀粉(DS=0.603)的添加不利于改善苹果酸淀粉酯的糊化和流变特性。利用相关性分析对苹果酸淀粉酯部分理化指标(溶解度、溶胀度和糊化特性)和面条的品质(蒸煮特性、质构特性和感官特性)进行了综合分析。苹果酸大米淀粉酯可以显著提升面条的整体品质,在本实验中,取代度为0.442时,小麦粉制备的面条品质较佳。展开更多
基金funded by the National Key Research and Development Program of China (2019YFD1001400)the National Natural Science Foundation of China (31601715)
文摘Organic acid content is one of the most important factors influencing fruit flavors.The predominant organic acid in most pear cultivars is malic acid,but the mechanism controlling its accumulation remains unclear.In this study,by comparing gene expression levels and organic acid contents,we found that the expression of PbPH5,which encodes a P_(3A)-ATPase,is highly correlated with malic acid accumulation in four different pear species,with correlation coefficients of 0.932**,0.656*,0.900**,and 0.518*(*,P<0.05;**,P<0.01)for Pyrus bretschneideri Rehd.,P.communis Linn.,P.pyrifolia Nakai.,and P.ussuriensis Maxim.,respectively.Moreover,the overexpression of PbPH5 in pear significantly increased the malic acid content.In contrast,silencing PbPH5 via RNA interference significantly decreased both its transcript level and the pear fruit malic acid content.A subcellular localization analysis indicated that PbPH5 is located in the tonoplast.Additionally,a phylogenetic analysis indicated that PbPH5 is a PH5 homolog gene that is clustered with the Petunia hybrida,Malus domestica,and Citrus reticulata genes.Considered together,these findings suggest that PbPH5 is a functionally conserved gene.Furthermore,the accumulation of malic acid in pear fruit is at least partly related to changes in the PbPH5 transcription levels.
基金the Project of International Cooperation between China and Ukraine(No.043-05)National Natural Science Foundation and Key Lab of Polymer Materials of Gansu Province for their financial supports.
文摘A novel kinetic method for determination of trace amounts of cobalt ion was proposed and validated. The method is based on adding malic acid into classical Belousov-Zhabotinskii （B-Z） oscillating chemical system to form a double substrate one. The results showed that when the concentration of cobalt ion was in the range of 5.27× 10^-8 to 5.37 × 10^-12 mol L^-1, the change of the oscillating period was directly proportional to the negative logarithm of cobalt ion concentration. The sensitivity and precision of the developed method were quite satisfactory. The limit of detection was down to 5.20 × 10^-13 mol L^-1 which was a highest sensitivity found for determination of metal ions using oscillating chemical reaction so far. Some factors influencing the determination were also examined. The method has been successfully used to determine cobalt ion in vitamin B12 injection.
基金supported by the Seoul Research and Business Development Program(No.10524).One of theauthors M.N.A.Khan is a recipient of Post-Doctoral fellowship from the post-BK2 1 program,Korea.
文摘A synthesis of methyl 2-hydroxy-4-oxo-4-（substituted phenyl）butanoates has been accomplished using Friedel-Crafts acylation of substituted benzenes with 2-acetoxybutanoyl chloride. The key feature of this strategy is that various 4-arylbutanoates can be obtained conveniently, which are important intermediates for the synthesis of biologically active compounds including ACE inhibitors.？2009 Yong Sup Lee. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.
文摘Ammonium tetramolybdate ( NH4 )4[(MoO2)4O3 (R-mal)2]·6H2O(mal= malic acid)and (NH4)4[(MoO2)4O3(S-mal)2)·6H2O have been prepared by the reaction of R and S-malic acid with ammonium heptamolybdate, respectively. The two complexes are enantiomeric and isomorphous. The complex of Risomer crystallizes in monoclinic space group C2 with unit cell parameters:a = 14. 591 (2 ), b = 10. 108(2), c=11. 464(2), β=121. 48(1)°, V=1441. 9(4),Z=2, Fω=1002. 13, Dc=2. 308, Dm=2. 3 g/cm3. F(000) = 988, MoKα radiation (λ=0. 71073 ), μ (MoKα) = 17. 7 cm-1. Final R=0. 027 for 1491 reflections with I>2. 5 σ(I). Analysis of molecular structure reveals that the complex anion contains a (Mo2O5)O(Mo2O5)core with the bridging oxo-group passing through two-fold axis. Each molybdenum is hexacoordinated , and the malate ligand is quadridentated to two molybdenum atoms by the deprotonated hydroxy-, α- and β-carboxylate groups. Principal dimensions are:[Mo=O(t)]av, 1. 705(6); [Mo-O(b)]av, 1. 920(6); Mo-O(hydroxy). 1. 925(6);Mo-O(α-carboxy), 2. 226 (6), and [Mo-O(β-carboxy)av, 2. 296 (5).Lattice water is distributed throughout the cell and together with various types of the anion oxygens, making H-bonding.
文摘Terpolymer of 1, 8-octanediol, adipic acid, and L-malic acid was synthesized via a lipase-catalyzed direct polycondensation. The products were characterized by GPC and 1H NMR. The results indicated that the molecular weight of the prepared polymers decreased with increasing L-malic acid content in the monomer feed ratio, and that change in the L-malic acid content from 0 to 20 mol % did not remarkably influenced on the molecular weight distribution Mw /Ma of the prepared samples. The 1H NMR spectra of the obtained copolymer samples showed that hydroxyl groups of L-malic acid did not take part in the polymerization reaction.
文摘In order to create a functionalized biodegradable polymer for vascular tissue engineering application,poly(DL- lactide-co-RS-β-malic acid)(PDLLMAc)was synthesized.PDLLMAc was obtained after hydrogenolysis of poly(DL- lactide-co-RS-β-benzyl malolactonate)(PDLLMA),which was from the ring-opening polymerization of DL-lactide(DLLA) and RS-β-benzyl malolactonate(MA)using stannous octoate as catalyst.The copolymers were characterized by ~1H-NMR, FTIR,GPC and DSC.The tensile strength and water uptake of the copoly...
文摘The effect of some phenolic compounds recurrent in wines on technological features of Oenococcus oeni was studied in order to individuate those strains to be utilized as starter in the deacidification of aged red wines. For this purpose, the growth and the L-malic acid metabolism of 100O. oeni strains, previously isolated from different wines, was assayed in a synthetic medium added with ethanol, malic acid and phenol carboxylic （gallic, caffeic, p-coumaric and ferulic） acids or flavonoids （catechin and quercetin） at different concentrations. Results evidenced a different sensitivity of strains to each assayed compound. All the compounds restrained or stimulated the growth of 57 and 11 strains respectively, while no effect was detected on 6 strains. The remaining 26 strains showed a different behaviour： all were restrained by ferulic acid and stimulated by gallic acid and catechin. As for caffeic acid, 17 out of 26 strains were restrained, while 9 strains were stimulated. The main result obtained in this study was the establishment of a relationship between the effect of phenolic compounds on the O. oeni growth and the behaviour of the malolactic fermentation. This study may enrich the selection criteria of strains for the deacidification of aged red wines.
基金the framework of budget project No.0303-2016-0006 for Boreskov Institute of Catalysis
文摘The catalyst preparation strategy was based on a strict introduction sequence of rhenium and platinum precursors and their strong interaction with carbon support resulted in the formation of 0.5 nm Pt-Re Ox species of atomic dispersion, where platinum is metallic, while monolayer rhenium is partially oxidized（Re2＋）. The reaction kinetics was studied taking into account the process of L-malic acid association leading to the formation of inactive cyclic oligomeric species. High TOFs（ca. 50 h-1）, selectivities（ca. 99%）and stability of Pt-Re Ox/C catalysts in aqueous-phase hydrogenation of L-malic acid, which are close to those of the homogeneous pincer type complexes, were revealed at mild conditions（T = 90–130 ℃）. Taking into account that（i） hydrogenation reaction occurred 2–3 orders of magnitude faster than its racemization and（ii） association of L-malic acid dominates at low temperatures and in a concentrated solution,special reaction conditions that allow obtaining chemically and optically（ee 〉 99%） pure（S）-3-hydroxy-γ-butyrolactone and（S）-1,2,4-butanetriol were found. Basing on HAADF-STEM, EDX, XPS, and kinetic studies, the structure of active species and basic reaction pathways are proposed.
基金supported by the local innovative and research teams project of Guangdong province(2019BT02N630)national key research and development program(2022YFD1300401)+2 种基金Double first-class discipline promoting project(2023B10564001)National Natural Science Foundation of China(32272954)Natural Science Foundation of Guangdong Province,China(2024A1515013131).
文摘Background Intestinal oxidative stress serves as an endogenous host defense against the gut microbiota by increas-ing energy expenditure and therefore decreasing feed efficiency(FE).Several systems coordinately regulate redox bal-ance,including the mitochondrial respiratory chain,nicotinamide adenine dinucleotide phosphate(NADPH)oxidase,and different antioxidants.However,it remains unclear which redox balance compartments in the intestine are crucial for determining FE.Results In this study,we first screened the key targets of different metabolites and redox balance-related gene expression in broiler ceca.We then constructed a mouse colitis model to explore malic acid(MA)ability to allevi-ate intestinal inflammation.We further used controlled release technology to coat MA and investigated its effects on the intestinal redox status and FE in vivo.Finally,we examined the underlying mechanism by which MA modulated redox status using a porcine intestinal epithelial cell jejunum 2(IPEC-J2)cell model in vitro.Our results demonstrated that the MA/malic enzyme 3(ME3)pathway may play an important role in reducing oxidative stress in the broiler cecum.In addition,colon infusion of MA attenuated inflammatory phenotypes in the dextran sulfate sodium salt(DSS)induced mouse colitis model.Then,dietary supplementation with controlled-release MA pellet(MAP)reduced the feed to gain(F/G)ratio and promoted chicken growth,with reduced oxidative stress and increased bacterial diver-sity.Finally,the in vitro IPEC-J2 cell model revealed that ME3 mediated the effect of MA on cellular oxidative stress.Conclusion In summary,our study firstly revealed the important role of the MA/ME3 system in the hindgut of broiler chickens for improving intestinal health and FE,which may also be crucial for the implications of colon inflammation associated diseases.
基金supported by the National Natural Science Foundation of China(Nos.22301034,22301033)the Jiangxi Provincial Natural Science Foundation(No.20232ACB213005)。
文摘A dimeric Y(III)-containing antimonotungstate[Y_(4)(H_(2)O)_(8)(mal)_(2)(OAc)O(Sb_(2)W_(2)^(V)W_(19)^(VI)O_(72))_(2)]^(21-)(Y_(4)mal_(2),H_(3)mal=DL-malic acid),resembling a“handshake”configuration,was synthesized and characterized.The polyanion of Y_(4)mal_(2)consists of two Dawson-derived{Y_(2)Sb_(2)W_(21)}moieties that are further linked by two mal ligands and oneμ_(2)-bridging acetate to form an asymmetric polyanion.Notably,the chiral configuration induced by the D-or L-configuration of the mal ligand results in both{Y_(2)Sb_(2)W_(21)}moieties within one polyanion exhibiting identical chirality,leading to the racemate crystallization of Y_(4)mal_(2).Moreover,Y_(4)mal_(2)exhibits excellent Lewis acid catalytic activity for environmentally friendly synthesis of imidazoles.
基金Supported by the National Natural Science Foundation of China (No. 29836130).
文摘Extraction equilibrium features of succinic acid, malic acid,maleic acid and fumaric acid were investi- gated systematically withtrioctylamine (TOA) in chloroform, 4-methyl-2-pentanone (MIBK) and1-octanol. Fourier transform-infrared (FTIR) spectroscopic analysisof organic samples loaded with the acid shows that amine forms 1:1complex of ion-pair association with succinic acid, malic acid andmaleic acid, and 1:1, 2:1 complex of ion-pair association withfumaric acid. It is proposed that the complex forms depend on thesecond dissociation constant of the dibasic acid, pK_a2.
文摘Crystals of the chiral malic acid hydrate (C_4H_6O_5·H_2O) were unexpectedlyobtained from an ethanol/water solution containing racemic D, L-malic acid and L-asparagine. Thecrystal belongs to orthorhombic space group P2_12_12_1 with cell dimensions of a = 0.5576(1), b =0.9818(2), c = 1.1793(2) nm, V = 0.6455(2) nm^3, Z = 4, μ(Mo K_a) =0.152 mm^(-1), F(000) = 320, D_c= 1.565 g·cm^(-3), R=0.051, wR = 0.136 for 657 observed reflections [ I > 2σ(I) ]. Thesignificant difference in bond distances for carboxyl groups suggests that the crystal consist ofmalate anion and protonized crystalline water. This is a report for direct separation of racemicmixture, i.e., without the formation of a molecular complex of raceme with a chiral separatingreagent.
文摘The protein family of 14-3-3(s) has risen to a position of higher importance as an adaptor protein in cell biology. The seven highly conserved human 14-3-3 proteins coordinate diverse cellular processes including apoptosis, DNA damage response, protein trafficking, and others. In liver hepatocytes, 14-3-3β binds to Ser196-phosphorilated glucose-responsive carbohydrate response element-binding protein (ChREBP) to inhibit converting excess carbohydrate to fat by regulating the nuclear/cytosol trafficking of ChREBP. Here, we report X-ray crystal structures of homodimeric mammalian 14-3-3β in its apo, Malate-bound forms. The determined apo structure was captured with one monomer in the closed state, whereas the other one had an open conformation. Strikingly, 14-3-3β binds Malate dynamically with a double-closed state, which is distinct from all previously characterized 14-3-3(s) and target ligand-binding modes. Malate docks into a first-time observed cofactor pocket located at the concaved interface of 14-3-3β helices α2, α3, α4 through mainly electrostatic and hydrogen interactions. Such a Tricarboxylic Acid Cycle intermediate Malate bond model might offer a new approach to further analyze insulin-independent 14-3-3/ChREBP pathway of de novo fat synthesis in the liver.
文摘为探究不同取代度(Degree of Substitution,DS)对苹果酸大米淀粉酯理化特性及对面条品质的影响,制备不同取代度(DS=0~0.603)苹果酸大米淀粉酯,考察了苹果酸大米淀粉酯溶解度、溶胀度、糊化特性和流变特性,以及对面条蒸煮特性、质构特性和感官特性的改善作用。结果表明,苹果酸淀粉酯的红外光谱分析显示在光谱波数约1720 cm-1处出现一个新的吸收峰。淀粉发生酯化反应后溶解度显著升高(P<0.05),但溶胀度有所下降。糊化和流变实验结果表明,低酯化淀粉(DS=0.141~0.442)的加入显著降低(P<0.05)了淀粉的峰值黏度,降低了苹果酸淀粉酯的储能模量G′和损耗模量G″,高酯化淀粉(DS=0.603)的添加不利于改善苹果酸淀粉酯的糊化和流变特性。利用相关性分析对苹果酸淀粉酯部分理化指标(溶解度、溶胀度和糊化特性)和面条的品质(蒸煮特性、质构特性和感官特性)进行了综合分析。苹果酸大米淀粉酯可以显著提升面条的整体品质,在本实验中,取代度为0.442时,小麦粉制备的面条品质较佳。
