Peroxiredoxin evolution and the regulation of hydrogen peroxide signaling

Eukaryotic 2-Cys peroxiredoxins (2-Cys Prxs) not only act as antioxidants, but also appear to regulate hydrogen peroxide-mediated signal transduction. We show that bacterial 2-Cys Prxs are much less sensitive to oxidative inactivation than are eukaryotic 2-Cys Prxs. By identifying two sequence motifs unique to the sensitive 2-Cys Prxs and comparing the crystal structure of a bacterial 2-Cys Prx at 2.2 angstrom resolution with other Prx structures, we define the structural origins of sensitivity. We suggest this adaptation allows 2-Cys Prxs to act as floodgates, keeping resting levels of hydrogen peroxide low, while permitting higher levels during signal transduction.     

施氮量对烤烟烟叶抗氧化系统及质量的影响

[目的]研究施氮量对烤烟烟叶抗氧化系统及质量的影响。[方法]以K326为试验材料,对不同施氮水平烤烟生长成熟期间烟叶活性氧含量、SOD活性、GR活性、APX活性、抗氧化剂含量、化学成分进行了研究。[结果]随着烟叶在田间的生长成熟,烟叶内超氧阴离子产生速率、过氧化氢的含量呈增加趋势;抗氧化酶活性整体呈先上升后下降的趋势;抗氧化剂GSH逐渐下降;As A含量在生长前期逐渐增加,但生长后期逐渐下降。不同施氮水平对烤烟烟叶生长成熟期间抗氧化系统有显著影响。在高氮水平下,烟叶内活性氧清除系统中的自由基清除剂(GSH、As A)和相关酶活性(SOD、GR、APX)均显著或极显著高于低氮水平处理。随着施氮量的增加,烤后烟叶含氮化合物显著增高,蛋白质、淀粉、叶绿素和类胡萝卜素等大分子物质降解量减少,石油醚提取物显著减少,但对钾和氯影响不显著,烟叶质量降低。[结论]烤烟大田管理中适量施氮(45.0 kg/hm2)有利于烟叶生长前期保持较高抗氧化活性,抵御胁迫,在成熟期确保适时成熟,提高烟叶质量。     

Growth,photosynthetic efficiency and metabolic alterations associated with exogenous hydrogen peroxide in <Emphasis Type="Italic">Artemisia annua</Emphasis>: Overproduction of artemisinin

Artemisinin, a sesquiterpene lactone with a peroxide linkage, has been held responsible for antimalarial activity of the Artemisia annua L. Recently, it was reported that reactive oxygen species (ROS) play important role in the biosynthesis of artemisinin by catalyzing some important intermediate steps. The effect of exogenously supplied hydrogen peroxide (1.00 mM and 2.00 mM H₂O₂), in two ways, foliar and as soil drench, was worked out in terms of growth, alteration in photosynthesis, oxidative damage, antioxidant defense enzymes and artemisinin level in exposed plants. Application of H₂O₂ positively affect the growth of the treated plants; and increment in net photo synthetic rate, stomatal conductance, internal CO₂ and chlorophyll content in the H₂O₂ exposed A. annua plants was noted. A significant upregulation in antioxidant enzymes viz. catalase (CAT), peroxidase (POX) and superoxide dismutase (SOD) was observed as a result of exogenous H₂O₂ treatment when applied foliarly or as soil drench. H₂O₂application either by 1.00 mM or 2.00 mM stimulated artemisinin levels, however, 2.00 mM H₂O₂ applied as soil drench elicited artemisinin production more rapidly compared to other treatments. Therefore, results suggest that exogenous H₂O₂ may stimulate growth by inducing antioxidant defense system and increase the artemisinin levels in Artemisia annua plants.     

植物乳杆菌C88对H2O2诱导氧化损伤的 Caco-2细胞的保护作用

【目的】文章旨在研究植物乳杆菌（Lactobacillus plantarum）C88的抗氧化作用。【方法】采用0.1 mmol•L-1 和0.2 mmol•L-1浓度H2O2连续处理Caco-2细胞12—48 h造成氧化损伤,通过测定细胞培养液上清和细胞裂解液的自由基清除能力及抗氧化物酶活性,评价植物乳杆菌C88对Caco-2细胞抗氧化损伤的保护作用。【结果】与氧化损伤模型组相比,植物乳杆菌C88在1011CFU/mL浓度下,能显著提高细胞裂解液的谷胱甘肽过氧化物酶（GSH-Px）活性(P＜0.05)和总抗氧化（T-AOC）能力(P＜0.05);以及细胞裂解液的羟自由基清除率(P＜0.05)、谷胱甘肽过氧化物酶（GSH-Px）(P＜0.05)和超氧化歧化酶（SOD）活性。细胞裂解液的羟自由基清除率低于氧化应激对照组。【结论】植物乳杆菌（L. plantarum）C88通过提高Caco-2细胞的自由基清除能力和抗氧化酶活性,表现出了较强的抗氧化活性。     

稻纵卷叶螟为害对水稻防御化合物及信号分子含量的影响

    测定稻纵卷叶螟Cnaphalocrocis medinalis(Guenee)为害后水稻体内过氧化氢、水杨酸、茉莉酸3种信号分子以及防御相关化合物含量的变化.结果表明,稻纵卷叶螟为害后0.5、24 h能显著提高水稻体内过氧化氢浓度,为害后0.5、1、24 h显著增加水杨酸浓度,但不影响茉莉酸浓度.稻纵卷叶螟为害能导致水稻叶片中胰蛋白酶抑制剂和6种未知防御化合物含量上升,在叶鞘中只引起6种未知物中的3种含量上升,其他的3种未知物与胰蛋白酶抑制剂没有明显变化.外用水杨酸或过氧化氢处理水稻只在叶鞘中增加6种未知物中1种化舍物的含量.说明稻纵卷叶螟为害诱导的防御化合物的变化部分是系统性的,而另一部分则是局部性的;并且稻纵卷叶螟为害诱导的防御反应是多种信号分子相互作用的结果.     

Transgenic Arabidopsis thaliana expressing a wheat oxalate oxidase exhibits hydrogen peroxide related defense response

Oxalic acid(OA) is considered as an important pathogenetic factor of some destructive diseases caused by some fungal pathogens such as Sclerotinia sclerotiorum. Oxalate degradation is important for plant health, and plants that contain oxalate oxidase(OXO) enzymes could breakdown oxalate into CO_2 and H_2O_2, which subsequently evokes defense responses. However, some species, such as Arabidopsis thaliana, have no oxalate oxidase activity identified to date. The present study aims to develop transgenic Arabidopsis expressing a wheat oxalate oxidase, to test for the response to OA exposure and fungal infection by S. sclerotiorum. The results showed that the transgenic Arabidopsis lines that expressed the wheat OXO exhibited enhanced resistance to OA exposure and S. sclerotiorum infection in the tolerance assays. In the same manner, it could convert OA to CO_2 and H_2O_2 to a higher extent than the wild-type. Intensive osmotic adjustments were also detected in the transgenic Arabidopsis lines. The higher level of produced H_2O_2 subsequently induced an elevated activity of antioxidant enzymes including superoxide dismutase(SOD) and peroxidase(POD) in the transgenic Arabidopsis plants. The present study indicated that the expression of a gene encoding wheat OXO could induce intensive osmotic adjustments and hydrogen peroxide related defense response, and subsequently increased tolerance to S. sclerotiorum in transgenic A. thaliana.     

参薯多糖检测及其体外抗氧化能力研究

以参薯(Dioscorea alata L.)块茎为研究材料,采用热水浸提、Savage法除蛋白、乙醇沉淀及有机溶剂纯化的方法,获得参薯粗多糖.通过蒽酮-硫酸显色法测定参薯的多糖含量,研究了参薯粗多糖体外对羟自由基(·OH)和过氧化氢(H2O2)的清除能力.结果表明:参薯多糖含量高达19.17％,参薯粗多糖对羟自由基(...     

山楂多酚类物质的提取及其抗氧化活性研究

[目的]研究山楂中多酚类物质的提取和体外抗氧化作用,为山楂作为抗氧化、抗衰老的保健食品的开发提供理论依据。[方法]通过70%乙醇提取与D101大孔吸附树脂纯化制备山楂多酚;采用铁离子还原/抗氧化能力测定法、邻苯三酚自氧化法、二苯代苦味酰基自由基(DPPH.)分析法及油脂过氧化值测定法,测定山楂多酚的体外抗氧化能力。[结果]纯化制备的山楂多酚含量为60.24%;山楂多酚对羟自由基(.OH)的50%清除率(IC50)为53.4μg/ml;对O2-.的50%清除率(IC50)为42.3μg/ml;对DPPH.的50%清除率(IC50)为63.3μg/ml;山楂多酚有较强的抗猪油氧化作用,能显著抑制猪油POV的增加。[结论]山楂多酚的提取工艺比较简单,有较强的体外抗氧化能力。     

Systemic signaling and acclimation in response to excess excitation energy in Arabidopsis

Land plants are sessile and have developed sophisticated mechanisms that allow for both immediate and acclimatory responses to changing environments. Partial exposure of low light-adapted Arabidopsis plants to excess light results in a systemic acclimation to excess excitation energy and consequent photooxidative stress in unexposed leaves. Thus, plants possess a mechanism to communicate excess excitation energy systemically, allowing them to mount a defense against further episodes of such stress. Systemic redox changes in the proximity of photosystem II, hydrogen peroxide, and the induction of antioxidant defenses are key determinants of this mechanism of systemic acquired acclimation.     

低温胁迫对菜用大豆生长、叶片活性氧及多胺代谢的影响

选用两种耐低温性不同的菜用大豆品种——‘沪宁95-1’(耐低温)和‘台湾75’(低温敏感),对低温胁迫下两者的生长、叶片活性氧及多胺代谢进行了比较。结果表明,低温胁迫后两者生物量积累显著受到抑制,但‘沪宁95-1’受抑制程度显著小于‘台湾75’;低温胁迫下两者叶片抗氧化酶活性、O·-2生成速率、H2O2和MDA含量均显著升高,但‘沪宁95-1’叶片抗氧化酶活性显著高于‘台湾75’,O·-2生成速率、H2O2和MDA含量则显著低于‘台湾75’;低温胁迫后‘沪宁95-1’叶片不同形态腐胺、亚精胺和精胺含量均显著上升,‘台湾75’叶片不同形态腐胺含量显著下降,游离态、结合态亚精胺和精胺含量显著上升,束缚态亚精胺和精胺含量变化不显著。以上结果表明,低温胁迫下不同形态腐胺、束缚态亚精胺和精胺与‘沪宁95-1’较低的生长抑制、较低的氧化损伤以及较高的保护酶活性有关,可能在菜用大豆耐寒性方面发挥重要作用。     

2个柽柳Prx基因的克隆及表达分析

过氧化还原蛋白（Prxs）是植物体内重要的抗氧化酶。为深入研究Prx基因在柽柳非生物胁迫中的作用,从柽柳cDNA文库中获得了2条Prx的单一序列ThPrx1与ThPrx2,其中ThPrx1为部分序列,ThPrx2为全长序列。生物信息学分析表明,2条ThPrx与植物Prx同源基因的氨基酸序列具有较高的同源性,并且ThPrx1和ThPrx2分别属于Prx的PrxⅡ和2-Cys Prxs亚家族。通过实时定量PCR对这2个ThPrx基因在不同非生物胁迫（NaCl、PEG、CdCl2、低温及ABA）处理的柽柳根和叶中的表达模式分析显示, 2个ThPrx基因在胁迫下的表达模式不同:NaCl、PEG和ABA均能够诱导ThPrx1基因在根中的表达,而CdCl2和低温胁迫则抑制了该基因在根和叶中的表达;ThPrx2基因在低温处理的柽柳中的表达量下降,其他胁迫处理不同程度上影响了ThPrx2基因的表达。结果表明,ThPrx1与ThPrx2是2个新的Prx基因,推测其可能参与植物的逆境胁迫过程。      

不同生长期藏药独一味酶促抗氧化功能的研究

独一味[Lamiophlomis rotata(Benth.)Kudo]是一种常用藏药.通过测定其药用器官内源抗氧化酶类活性和脂质过氧化产物含量和速率,研究了不同采收期独一味各药用器官的酶促抗氧化功能.结果表明,独一味植株各药用器官中SOD酶活性均较高且稳定,平均达到150.87 U/g,H2O2清除酶类活性协同作用强,尤其POD活性强,平均达到236.76μmol/g,同时还具有高效AsA-GSH自由基清除循环体系,丙二醛(MDA)积累量很少,平均只有1.22μmol/g,因此认为独一味植株具有高效抗氧化功能和较优越的抗逆能力.     

Coordinate induction of antioxidant defense and glyoxalase system by exogenous proline and glycinebetaine is correlated with salt tolerance in mung bean

The purpose of this study was to assess the synergistic effects of exogenously applied proline and glycinebetaine (betaine) in antioxidant defense and methylglyoxal (MG) detoxification system in mung bean seedlings subjected to salt stress (200 mmol·L⁻¹ NaCl, 48 h). Seven-day-old mung bean seedlings were exposed to salt stress after pre-treatment with proline or betaine. Salt stress caused a sharp increase in reduced glutathione (GSH) and oxidized glutathione (GSSG) content in leaves, while the GSH/GSSG ratio and ascorbate (AsA) content decreased significantly. The glutathione reductase (GR), glutathione peroxidase (GPX), glutathione S-transferase (GST) and glyoxalase II (Gly II) activities were increased in response to salt stress, while the monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), catalase (CAT) and glyoxalase I (Gly I) activities sharply decreased with an associated increase in hydrogen peroxide (H₂O₂) and lipid peroxidation level (MDA). Proline or betaine pre-treatment had little influence on nonenzymatic and enzymatic components as compared to those of the untreated control. However, proline or betaine pre-treated salt-stressed seedlings showed an increase in AsA, GSH content, GSH/GSSG ratio and maintained higher activities of APX, DHAR, GR, GST, GPX, CAT, Gly I and Gly II involved in ROS and MG detoxification system as compared to those of the untreated control and mostly also salt-stressed plants with a simultaneous decrease in GSSG content, H₂O₂ and MDA level. These results together with our previous results suggest that coordinate induction of antioxidant defense and glyoxalase system by proline and betaine rendered the plants tolerant to salinity-induced oxidative stress in a synergistic fashion.     

H2O2和ABA对干旱高温复合胁迫诱导的玉米叶片抗氧化防护基因表达的影响

为确定H2O2和脱落酸(ABA)对干旱高温复合胁迫诱导的苗期玉米(Zea mays L.)叶片抗氧化防护系统的影响,利用玉米ABA缺失突变体vp5及其野生型Vp5为试验材料,在不同胁迫下使用H2O2清除剂KI,ABA抑制剂钨酸钠(T)预处理后,测定了体内4个抗氧化防护基因SOD4,GR1,CAT1和cAPX的表达.结果...     

猕猴桃根提取物体外抗氧化活性研究

[目的]探讨猕猴桃根提取物的体外抗氧化作用。[方法]采用DPPH自由基、超氧阴离子、羟基自由基、过氧化氢和还原力反应体系,测定猕猴桃根提取物的体外抗氧化作用,并用维生素C进行对照试验。[结果]试验条件下,ERHM对DPPH自由基、超氧阴离子（O2-.）、羟基自由基（.OH）、过氧化氢（H2O2）等均有较强的清除或抑制作用,且显示较好的量效关系,同时具有一定的还原力。其消除DPPH自由基的EC50为8.03μg/ml,清除超氧阴离子（O 2-.）的EC50为1.28 mg/ml,抑制羟基自由基（.OH）能力可达69.4%,浓度为100μg/ml时,对过氧化氢（H2O2）的清除率为42%。[结论]猕猴桃根提取物具有较强的还原力,能有效清除DPPH和超氧阴离子自由基,并抑制羟基自由基的产生。所以,ERHM有效成分具有较为显著的抗氧化作用。     

七种植物提取物对猪油的抗氧化性研究

为了研究甘草、花生壳等天然提取物的抗氧化活性，采用查理烘箱法高温诱导猪油发生过氧化反应。测定其过氧化值作为评价抗氧化性能的依据。结果表明：七种天然提取物皆可有效地延缓猪油的过氧化反应，且在0．05％～0．2％浓度范围内其抗氧化能力随添加量的增加而增强。甘草、花生壳、核桃叶提取物的抗氧化活性较强，甘草添加量为0．2％以下时与0．2％茶多酚及n位相当，当甘草添加量为0．2％时抗氧化性已超过了0．2％的茶多酚。为更深入的研究和开发本地区天然抗氧化剂提供参考依据。     

TiO2纳米颗粒增强的过氧化氢生物传感器

采用TiO2纳米颗粒与聚乙烯醇缩丁醛（PVB）作为固酶基质,用凝胶-溶胶法固定辣根过氧化物酶（HRP）,构成的过氧化氢生物传感器,研究了该修饰电极在磷酸缓冲液中对H2O2的催化作用及实验条件的影响,实验结果表明,纳米TiO2颗粒的引入可以明显的提高HRP对H2O2响应电流。     

Characteristics of NaCl-induced oxidative stress and dynamics of antioxidant enzyme activity in winter triticale organs

The characteristics of development of oxidative stress and change in activity of antioxidant enzymes in winter triticale shoots and roots under the effect of 120 mM NaCl are investigated. It is shown that the salinity stress response of plants has a diphasic character. The stress response phase (12?C24 h) is characterized by a 2.5-fold increase in the amount of hydrogen peroxide and, accordingly, in the intensity of lipid peroxidation, diagnosed by the increase in the amount of malondialdehyde by 2?C3 times in the plant shoots and roots. Both the H₂O₂ level and intensity of oxidative processes stabilized in the next phase of specific adaptation (24?C96 h). A general tendency of a change in the activity of guaiacol peroxidase and catalase, enzymes decomposing hydrogen peroxide in roots and shoots, is not found.     

Reversible reduction of oxygen to peroxide facilitated by molecular recognition

Generation of soluble sources of peroxide dianion (O(2)(2-)) is a challenge in dioxygen chemistry. The oxidizing nature of this anion renders its stabilization in organic media difficult. This Report describes the chemically reversible reduction of oxygen (O(2)) to cryptand-encapsulated O(2)(2-). The dianion is stabilized by strong hydrogen bonds to N-H groups from the hexacarboxamide cryptand. Analogous stabilization of peroxide by hydrogen bonding has been invoked recently in crystalline saccharide and protein systems. The present peroxide adducts are stable at room temperature in dimethyl sulfoxide (DMSO) and N,N'-dimethylformamide (DMF). These adducts can be obtained in gram quantities from the cryptand-driven disproportionation reaction of potassium superoxide (KO(2)) at room temperature.     

Substitution of the thioredoxin system for glutathione reductase in Drosophila melanogaster

The disulfide reducing enzymes glutathione reductase and thioredoxin reductase are highly conserved among bacteria, fungi, worms, and mammals. These proteins maintain intracellular redox homeostasis to protect the organism from oxidative damage. Here we demonstrate the absence of glutathione reductase in Drosophila melanogaster, identify a new type of thioredoxin reductase, and provide evidence that a thioredoxin system supports GSSG reduction. Our data suggest that antioxidant defense in Drosophila, and probably in related insects, differs fundamentally from that in other organisms.