新型兼具GPX,SOD, CAT活性的水杨醛Schiff碱衍生物的合成

以5-磺基水杨醛为母体, 经氯甲基化和硒化反应引入催化基团-SeH, 此化合物经空气氧化、Schiff碱反应以及锰螯合反应, 最终得到一种新型的水杨醛Schiff碱类谷胱甘肽过氧化物酶(GPX)模拟物. 测定了该模拟物的红外光谱、核磁共振谱、质谱和抗氧化能力. 此模拟物同时兼具超氧化物歧化酶(SOD)和过氧化氢酶(CAT)活性, 水溶性好, 保护线粒体免遭氧化损伤能力强, 具有作为药物前体的潜力.     

New Insight into the Mode of Action of Nickel Superoxide Dismutase by Investigating Metallopeptide Substrate Models

For the first time, the existence of a substrate adduct of a nickel superoxide dismutase (NiSOD) model, based on the first nine residues from the N terminus of the active form of Streptomyces coelicolor NiSOD, has been proven and the adduct has been isolated. This adduct is based on the cyanide anion (CN^?), as a substrate analogue of the superoxide anion (O₂^.?), and the nickel metallopeptide H‐HCDLPCGVY‐NH₂‐Ni. Spectroscopic studies, including IR, UV/Vis, and liquid‐ and solid‐state NMR spectroscopy, show a single nickel‐bound cyanide anion, which is embedded in the metallopeptide structure. This complex sheds new light on the question of whether the mode of action of the NiSOD enzyme is an inner‐ or outer‐sphere mechanism. Whereas discussion was previously biased in favor of an outer‐sphere electron‐transfer mechanism due to the fact that binding of cyanide or azide moieties to the nickel active site had never been observed, our results are a clear indication in favor of the inner‐sphere electron‐transfer mechanism for the disproportionation of the O₂^.? ion, whereby the substrate is attached to the Ni atom in the active site of the NiSOD.     

SOD及其电子迁移促进剂L-半胱氨酸的Raman光谱

在以电化学方法证实了L－半胱氨酸对铜锌－超氧化物歧化酶在金丝电极上的电子传递过程起有效促进作用的基础上,应用共焦显微激光拉曼光谱测试技术对固体的L－半胱氨酸和铜锌－超氧化物歧化酶进行了测定和光谱分析,并对以电化学和浸渍两种不同方法修饰在金电极上的L－半胱氨酸,也作了相应的拉曼光谱测试研究。     

Purification and Characterization of Superoxide Dismutase （SOD） from Camellia Pollen

A superoxide dismutase（ SOD ） was purified to homogeneity from fresh camellia pollen by means of ammonium sulfate precipitation and column chromatography with DEAE-cellulose（ DE52 ）, Sephadex G-100 and phenyl sepharose^TM 6 Fast Flow columns. Its specific activity could reach to 4034 U/mg protein and it was determined to be Cu/ Zn-SOD according to its different sensitivities to different inhibitors. The molecular weight of the SOD and its subunit were 69500 and 34700, respectively, based on sodium dodecyl sulfate-polyacrylamide gel electrophoresis （SDS- PAGE）, which implicates that the SOD in camellia pollen is a dimmer composed of two identical subunits. The isoelectric point of the enzyme was determined to be 4. 1 by isoelectric focusing electrophoresis and the N-terminal amino acid was identified to be Gly by the DNS-Cl method. Its α-Helix was also calculated to be approximately 21.8% according to the circular dichroism（CD） spectra.     

电化学原位拉曼光谱技术对金电极表面生物分子吸附行为研究

报道腺嘌呤在裸金电极及其修饰的金电极上的电化学原位拉曼光谱图 ,着重分析了不同电位下腺嘌呤和超氧化物歧化酶在金电极上的吸附及其相互作用 ,初步讨论了腺嘌呤对促进超氧化物歧化酶电子传递过程的作用机制 .     

Copper(II) complexes of hydroxyflavone derivatives as potential bioactive molecule to combat antioxidants: synthesis,characterization and pharmacological activities

A variety of novel copper complexes were synthesized and characterized of the formulae [Cu(L¹)(OAc)], [CuL²(H₂O)], [CuL³(H₂O)], [CuL⁴(OAc)], [CuL⁵(H₂O)] [CuL⁶], [CuL⁷], [CuL⁸](OAc) and [CuL⁹], where L¹ L⁹ represents Schiff base ligands [derived by the condensation of 5‐hydroxyflavone with 4‐aminoantipyrine (L¹), o‐aminophenol (L²), o‐aminobenzoic acid (L³), o‐aminothiazole (L⁴), thiosemicarbazide (L⁵), 4‐aminoantipyrine‐o‐aminophenol (L⁶), 4‐aminoantipyrine‐o‐aminobenzoic acid (L⁷), 4‐aminoantipyrine‐o‐aminothiazole(L⁸) and 4‐aminoantipyrine‐thiosemicarbazide (L⁹)]. The spectral and magnetic results of the Cu(II) complexes exhibit square planar geometry. The DNA binding properties of copper complexes were studied by using electronic absorption spectra, viscosity and thermal denaturation experiments. The results show that the complexes were interacting with calf thymus (CT DNA). The in vitro antimicrobial activities of the investigated compounds were tested against the bacterial species and fungal species. Superoxide dismutase and antioxidant activities of the copper complexes have also been studied. Copyright © 2011 John Wiley & Sons, Ltd.     

La-O小团簇上超氧物种与过氧物种间的连接途径

采用密度泛函理论方法考察了La-O团簇上超氧物种与过氧物种间转化的连接途径. 单重态下, 团簇上单个超氧物种可通过一系列臭氧物种转化为过氧物种, 且转化能垒较高;三重态下, 单个超氧物种则并无与过氧物种间连接的途径. 然而, La-O团簇上两超氧物种间的相互作用及其转化也具单重态和三重态两条途径. 三重态下, 超氧物种可很容易地转化为过氧物种(O₂^- + O₂^-↔O₂^2- + O₂), 超氧物种与过氧物种处于快速的交换状态之中;单重态下, 超氧物种转化为过氧物种则需较高的活化能垒, 表明在单重态下这些氧物种具有较高的稳定性.     

Cytochrome c‐Based Amperometric Sensors for Superoxide Detection: Where Their Signal Comes From?

In a popular amperometric superoxide sensor, cytochrome c (Cyt c) is covalently immobilized onto a gold electrode previously covered with a self‐assembled monolayer (SAM) of carboxyl‐terminated alkanethiols. Therefore, a study was carried out to reveal the origins of the current response of such sensors. SAMs made of either 3,3′‐dithiodipropionic acid or 11‐mercaptoundecanoic acid and 11‐mercaptoundecanol were used to immobilize either Cyt c or an inert protein onto gold electrodes. The resulting modified electrodes were comparatively investigated by cyclic voltammetry and calibrated for superoxide detection. The obtained results bring evidence that significant part (>70 %) of the current response of the Cyt c‐modified electrodes to superoxide comes from direct oxidation of superoxide on gold (i.e. does not involve Cyt c).     

A theoretical study on the reaction pathways of peroxynitrite formation and decay at nonheme iron centers

A computational study based on density functional theory was undertaken to identify possible reaction pathways for the formation and decomposition of peroxynitrite at models of the active sites of the nonheme superoxide scavenging enzymes superoxide reductase (SOR) and iron superoxide dismutase (FeSOD). Two peroxynitrite isomers and their possible protonated states were investigated, namely Fe? OONO^?, Fe? N(O)OO^?, Fe? OONOH, and Fe? N(O)OOH. Peroxynitrite formation at the active sites was assumed by either the interaction of a peroxynitrite cis/trans anion with the pentacoordinated iron active site or the interaction between a nitric oxide bound adduct and superoxide; both scenarios were found to be facile for all models investigated. The ferrous adducts of the Fe? OONO^?isomer were found to undergo instant heterolytic cleavage of the O? ONO bond to yield nitrite, whereas for the ferric adducts, the homolytic cleavage of the O? ONO bond to yield nitrogen dioxide was found to be energetically facile. For the Fe? N(O)OO^? isomer, the active site models of FeSOD and SOR were only able to accommodate the cis isomer of peroxynitrite. Ferric adducts of the cis Fe? OONO^? isomer were found to be energetically more stable than their trans counterparts and were also more stable than the cis adducts of the Fe? N(O)OO^? isomer; conversely, the protonated forms of all adducts of the Fe? OONOH isomer were found to be lower in energy than their equivalent Fe? N(O)OOH adducts. Multiple reaction pathways for the decomposition of the formed peroxynitrite adducts (whether the anions or the protonated forms) were proposed and explored. The energy requirements for the decomposition processes ranged from exothermic to highly demanding depending on the peroxynitrite isomer, the type of model (whether an SOR or FeSOD active site), and the oxidation state of iron. © 2014 Wiley Periodicals, Inc.     

Synthesis and structural characterization of an anti-inflammatory principle purified from Lindera aggregata

Linderaggrine A (1) was characterized from the roots of Lindera aggregata and its chemical structure was established by the spectral analysis and chemical transformation. The chemical preparation of 1 and its isomer 2 provide unambiguous evidences for the structural determination of the naturally isolated compound. In addition, the inhibition of superoxide anion generation and elastase release by human neutrophils in response to FMLP/cytochalasin B of these synthetic products had been examined and among the tested compounds, linderaggrine A (1) displayed significant potential against the superoxide anion generation.