By using polyacrylamide gel electrophoresis and biochemical straining method, malic enzyme isozyme in 10 organs of male or female Varicorhinus macrolepis were analyzed. The results showed that malic enzyme exists in h...By using polyacrylamide gel electrophoresis and biochemical straining method, malic enzyme isozyme in 10 organs of male or female Varicorhinus macrolepis were analyzed. The results showed that malic enzyme exists in heart, gonads, eyes and gills tissues in both female and male V. macrolepis. There was only one ME-2 in heart and ME-1 in eye of female fish, while there were ME-1 and ME-2 in heart and ME-2 in eyes of male fish. Ovary contained ME-1 and ME-2, while spermary only contained ME-1. In kidney and spleen tissues, malic enzyme was found only in female fish, while in muscle, malic enzyme existed only in male fish. The phenotypic of malic enzyme had obvious differences no matter in the same organ of different sexes in V. macrolepis or different organs in the same sex. But there were no differences among different individuals of the same sex. The results will provide basic data for developmental genetics, breed improvement and directed breeding of V. macrolepis, and lay a foundation for its development and protection.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
Objective: α-ketoglutarate(α-KG) is the substrate to hydroxylate collagen and hypoxia-inducible factor-1α(HIF-1α), which are important for cancer metastasis. Previous studies have shown that the upregulation of co...Objective: α-ketoglutarate(α-KG) is the substrate to hydroxylate collagen and hypoxia-inducible factor-1α(HIF-1α), which are important for cancer metastasis. Previous studies have shown that the upregulation of collagen prolyl 4-hydroxylase in breast cancer cells stabilizes the expression of HIF-1α by depleting α-KG levels. We hypothesized that mitochondrial malic enzyme 2(ME2) might also affect HIF-1α expression via modulating α-KG levels in breast cancer cells.Methods: We evaluated ME2 protein expression in 100 breast cancer patients using immunohistochemistry and correlated with clinicopathological indicators. The effect of ME2 knockout on cancer metastasis was evaluated using an orthotopic breast cancer model. The effect of ME2 knockout or knockdown on the levels of α-KG and HIF-1α proteins in breast cancer cell lines was determined both in vitro and in vivo.Results: ME2 was found to be upregulated in the human breast cancerous tissues compared with the matched precancerous tissues(P<0.001). The elevated expression of ME2 was associated with a poor prognosis(P=0.019).ME2 upregulation was also related to lymph node metastasis(P=0.016), pathological staging(P=0.033), and vascular cancer embolus(P=0.014). Also, ME2 knockout significantly inhibited lung metastasis in vivo. In the tumors formed by ME2 knockout cells, the levels of α-KG were significantly increased and collagen hydroxylation level did not change significantly but HIF-1α protein expression was significantly decreased, compared to the control samples. In cell culture, cells with ME2 knockout or knockdown demonstrated significantly higher α-KG levels but significantly lower HIF-1α protein expression than control cells under hypoxia. Exogenous malate and α-KG exerted similar effect on HIF-1α in breast cancer cells to ME2 knockout or knockdown. Additionally,treatment with malate significantly decreased 4 T1 breast cancer lung metastasis. ME2 expression was associated with HIF-1α levels in human breast cancer samples(P=0.008).Conclusions: Our results provide evidence that upregulation of ME2 is associated with a poor prognosis of breast cancer patients and propose a mechanistic understanding of a link between ME2 and breast cancer metastasis.展开更多
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 new Belousov-Zhabotinskii oscillator in the malic acid-NaBrO3-H2SO4-[CuL](CIO4) 2 system, where L is 5. 7, 12, 14-tetraethyl-7, 14-dimethyl-1, 4, 8, 11-tetraazacyclotetradeca-4,11-diene, is reported
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
[ Objective] To investigate the relationship between muscular malic enzyme （ME） activity and meat quality in pigs. [ Method] Three pig breeds, Exi pigs, Changye x Exi hybrid pigs and Landrace xYorkshire pigs were se...[ Objective] To investigate the relationship between muscular malic enzyme （ME） activity and meat quality in pigs. [ Method] Three pig breeds, Exi pigs, Changye x Exi hybrid pigs and Landrace xYorkshire pigs were selected. Then the ME activity and meat traits were detected, and the relationship between ME activity and meat quality were analyzed with SAS software. [ Result] The Exi pigs had the highest ME activity and intra- muscular fat （IMF） content （ P 〈 0.05）. The pH2 value, drip loss and muscle shear force of Landrace xYorkshire pigs were higher than that of Exi pigs significantly （P 〈 0.05）. [ Conclusion] The ME activity has a certain correlation with meat quality of pigs. The muscular ME activity has signifi- cantly positive correlation with IMF content and significantly negative correlation with drip loss and muscle shear force.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
A large amount of nicotinamide adenine dinucleotide phosphate(NADPH) is required for fatty acid synthesis and maintenance of the redox state in cancer cells.Malic enzyme 1(ME1)-dependent NADPH production is one of the...A large amount of nicotinamide adenine dinucleotide phosphate(NADPH) is required for fatty acid synthesis and maintenance of the redox state in cancer cells.Malic enzyme 1(ME1)-dependent NADPH production is one of the three pathways that contribute to the formation of the cytosolic NADPH pool.ME1 is generally considered to be overexpressed in cancer cells to meet the high demand for increased de novo fatty acid synthesis.In the present study,we found that glucose induced higher ME1 activity and that repressing ME1 had a profound impact on glucose metabolism of nasopharyngeal carcinoma(NPC) cells.High incorporation of glucose and an enhancement of the pentose phosphate pathway were observed in ME1-repressed cells.However,there were no obvious changes in the other two pathways for glucose metabolism:glycolysis and oxidative phosphorylation.Interestingly,NADPH was decreased under low-glucose condition in ME1-repressed cells relative to wild-type cells,whereas no significant difference was observed under high-glucose condition.ME1-repressed cells had significantly decreased tolerance to low-glucose condition.Moreover,NADPH produced by ME1 was not only important for fatty acid synthesis but also essential for maintenance of the intracellular redox state and the protection of cells from oxidative stress.Furthermore,diminished migration and invasion were observed in ME1-repressed cells due to a reduced level of Snail protein.Collectively,these results suggest an essential role for ME1 in the production of cytosolic NADPH and maintenance of migratory and invasive abilities of NPC cells.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
In order to remove phosphorus element from steelmaking slag and decrease iron loss,malic acid was selected as the leaching agent to dissolve steelmaking slag.Firstly,the influences of different factors,such as malic a...In order to remove phosphorus element from steelmaking slag and decrease iron loss,malic acid was selected as the leaching agent to dissolve steelmaking slag.Firstly,the influences of different factors,such as malic acid concentration,slag particle size,temperature,liquid/solid ratio and stirring speed,on the leaching ratios of phosphorus and iron were studied.Then,the kinetics for the leaching process of phosphorus was analyzed.The results showed that the leaching ratios of phosphorus and iron increase significantly with increasing the malic acid solution concentration and liquid/solid ratio.When the concentration of malic acid solution increases up to 0.01492 mol/L,about 80%phosphorus can be dissolved,and iron leaching ratio is less than 17%.In addition,decreasing slag particle size can obviously increase the leaching ratio of phosphorus.However,temperature and stirring speed have no significant effect on the dissolution of phosphorus and iron.The leaching kinetics of phosphorus follows the unreacted shrinking core model.Diffusion through product layer is the rate-limiting step of the leaching process,and the corresponding apparent activation energy is determined to be 3.32 kJ/mol.Finally,a semi-empirical kinetic equation was established.展开更多
基金Supported by the National Natural Science Foundation of China(39770091)~~
文摘By using polyacrylamide gel electrophoresis and biochemical straining method, malic enzyme isozyme in 10 organs of male or female Varicorhinus macrolepis were analyzed. The results showed that malic enzyme exists in heart, gonads, eyes and gills tissues in both female and male V. macrolepis. There was only one ME-2 in heart and ME-1 in eye of female fish, while there were ME-1 and ME-2 in heart and ME-2 in eyes of male fish. Ovary contained ME-1 and ME-2, while spermary only contained ME-1. In kidney and spleen tissues, malic enzyme was found only in female fish, while in muscle, malic enzyme existed only in male fish. The phenotypic of malic enzyme had obvious differences no matter in the same organ of different sexes in V. macrolepis or different organs in the same sex. But there were no differences among different individuals of the same sex. The results will provide basic data for developmental genetics, breed improvement and directed breeding of V. macrolepis, and lay a foundation for its development and protection.
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.
基金supported in part by the China Natural Sciences Foundation projects (No. 81772947)。
文摘Objective: α-ketoglutarate(α-KG) is the substrate to hydroxylate collagen and hypoxia-inducible factor-1α(HIF-1α), which are important for cancer metastasis. Previous studies have shown that the upregulation of collagen prolyl 4-hydroxylase in breast cancer cells stabilizes the expression of HIF-1α by depleting α-KG levels. We hypothesized that mitochondrial malic enzyme 2(ME2) might also affect HIF-1α expression via modulating α-KG levels in breast cancer cells.Methods: We evaluated ME2 protein expression in 100 breast cancer patients using immunohistochemistry and correlated with clinicopathological indicators. The effect of ME2 knockout on cancer metastasis was evaluated using an orthotopic breast cancer model. The effect of ME2 knockout or knockdown on the levels of α-KG and HIF-1α proteins in breast cancer cell lines was determined both in vitro and in vivo.Results: ME2 was found to be upregulated in the human breast cancerous tissues compared with the matched precancerous tissues(P<0.001). The elevated expression of ME2 was associated with a poor prognosis(P=0.019).ME2 upregulation was also related to lymph node metastasis(P=0.016), pathological staging(P=0.033), and vascular cancer embolus(P=0.014). Also, ME2 knockout significantly inhibited lung metastasis in vivo. In the tumors formed by ME2 knockout cells, the levels of α-KG were significantly increased and collagen hydroxylation level did not change significantly but HIF-1α protein expression was significantly decreased, compared to the control samples. In cell culture, cells with ME2 knockout or knockdown demonstrated significantly higher α-KG levels but significantly lower HIF-1α protein expression than control cells under hypoxia. Exogenous malate and α-KG exerted similar effect on HIF-1α in breast cancer cells to ME2 knockout or knockdown. Additionally,treatment with malate significantly decreased 4 T1 breast cancer lung metastasis. ME2 expression was associated with HIF-1α levels in human breast cancer samples(P=0.008).Conclusions: Our results provide evidence that upregulation of ME2 is associated with a poor prognosis of breast cancer patients and propose a mechanistic understanding of a link between ME2 and breast cancer metastasis.
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.
文摘A new Belousov-Zhabotinskii oscillator in the malic acid-NaBrO3-H2SO4-[CuL](CIO4) 2 system, where L is 5. 7, 12, 14-tetraethyl-7, 14-dimethyl-1, 4, 8, 11-tetraazacyclotetradeca-4,11-diene, is reported
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.
基金supported by the Natural Science Funds of Hubei Province(2008CDZ083)Youth Funds of the Education Department of Hubei Province(Q20091202)Innovation Projects of Yangtze University(0916)
文摘[ Objective] To investigate the relationship between muscular malic enzyme （ME） activity and meat quality in pigs. [ Method] Three pig breeds, Exi pigs, Changye x Exi hybrid pigs and Landrace xYorkshire pigs were selected. Then the ME activity and meat traits were detected, and the relationship between ME activity and meat quality were analyzed with SAS software. [ Result] The Exi pigs had the highest ME activity and intra- muscular fat （IMF） content （ P 〈 0.05）. The pH2 value, drip loss and muscle shear force of Landrace xYorkshire pigs were higher than that of Exi pigs significantly （P 〈 0.05）. [ Conclusion] The ME activity has a certain correlation with meat quality of pigs. The muscular ME activity has signifi- cantly positive correlation with IMF content and significantly negative correlation with drip loss and muscle shear force.
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 grants from the Major State Basic Research Program (973 Project) of China(No.2006CB910104 and 2010CB912201)the National High Technology Research and Development Program of China (863 Program) (No.20060102A4002)+1 种基金the State Key Program of National Natural Science Foundation of China (No.81030043)the Guangdong Province-National Natural Science Foundation of China Cooperation Program (No.u0732005)
文摘A large amount of nicotinamide adenine dinucleotide phosphate(NADPH) is required for fatty acid synthesis and maintenance of the redox state in cancer cells.Malic enzyme 1(ME1)-dependent NADPH production is one of the three pathways that contribute to the formation of the cytosolic NADPH pool.ME1 is generally considered to be overexpressed in cancer cells to meet the high demand for increased de novo fatty acid synthesis.In the present study,we found that glucose induced higher ME1 activity and that repressing ME1 had a profound impact on glucose metabolism of nasopharyngeal carcinoma(NPC) cells.High incorporation of glucose and an enhancement of the pentose phosphate pathway were observed in ME1-repressed cells.However,there were no obvious changes in the other two pathways for glucose metabolism:glycolysis and oxidative phosphorylation.Interestingly,NADPH was decreased under low-glucose condition in ME1-repressed cells relative to wild-type cells,whereas no significant difference was observed under high-glucose condition.ME1-repressed cells had significantly decreased tolerance to low-glucose condition.Moreover,NADPH produced by ME1 was not only important for fatty acid synthesis but also essential for maintenance of the intracellular redox state and the protection of cells from oxidative stress.Furthermore,diminished migration and invasion were observed in ME1-repressed cells due to a reduced level of Snail protein.Collectively,these results suggest an essential role for ME1 in the production of cytosolic NADPH and maintenance of migratory and invasive abilities of NPC cells.
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This work was financially supported by the National Natural Science Foundation of China(52074004 and 51604003)Director Fund of Anhui Province Key Laboratory of Metallurgical Engineering and Resources Recycling(Anhui University of Technology)and Anhui Special Support Plan(T000609).
文摘In order to remove phosphorus element from steelmaking slag and decrease iron loss,malic acid was selected as the leaching agent to dissolve steelmaking slag.Firstly,the influences of different factors,such as malic acid concentration,slag particle size,temperature,liquid/solid ratio and stirring speed,on the leaching ratios of phosphorus and iron were studied.Then,the kinetics for the leaching process of phosphorus was analyzed.The results showed that the leaching ratios of phosphorus and iron increase significantly with increasing the malic acid solution concentration and liquid/solid ratio.When the concentration of malic acid solution increases up to 0.01492 mol/L,about 80%phosphorus can be dissolved,and iron leaching ratio is less than 17%.In addition,decreasing slag particle size can obviously increase the leaching ratio of phosphorus.However,temperature and stirring speed have no significant effect on the dissolution of phosphorus and iron.The leaching kinetics of phosphorus follows the unreacted shrinking core model.Diffusion through product layer is the rate-limiting step of the leaching process,and the corresponding apparent activation energy is determined to be 3.32 kJ/mol.Finally,a semi-empirical kinetic equation was established.
