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1.
植物谷胱甘肽过氧化物酶研究进展   总被引:2,自引:0,他引:2       下载免费PDF全文
苗雨晨  白玲  苗琛  陈珈  宋纯鹏 《植物学报》2005,22(3):350-356
氧化胁迫可诱导植物多种防御酶的产生, 其中包括超氧化物歧化酶(SOD, EC1.15.1.1)、抗坏血酸过氧化物酶(APX, EC1.11.1.11)、过氧化氢酶(CAT, E.C.1.11.1.6 )和谷胱甘肽过氧化物酶(GPXs,EC1.11.1.9)。它们在清除活性氧过程中起着不同的作用。GPXs是动物体内清除氧自由基的主要酶类,但它在植物中的功能报道甚少。最近几年研究表明, 植物体内也存在类似于哺乳动物的GPXs家族, 并对其功能研究已初见端倪。本文综述了有关GPXs的结构以及植物GPXs功能的研究进展。  相似文献   

2.
植物抗坏血酸过氧化物酶的作用机制、酶学及分子特性   总被引:51,自引:1,他引:50  
介绍叶绿体中H2O2的产生和清除,抗坏血酸过氧化物酶(APX)的酶学和分子特性,APX同工酶在植物体内的分布和功能及其相互之间的区别,APX与细胞色素C过氧化酶(CPX)和谷胱苷肽过氧化物酶(GPX)等一些在不同生物中的H2O2清除酶的异同之处,以及有关APX基因工程的研究进展.  相似文献   

3.
草鱼胞浆谷胱甘肽过氧化物酶cDNA全长的克隆与分析   总被引:2,自引:1,他引:1  
谷胱甘肽过氧化物酶(glutathione peroxidases,GPXs,EC1.11.19)是生物体内抗氧化防御系统的重要组成部分。本文从草鱼(Ctenopharyngodon idellus)克隆到胞浆谷胱甘肽过氧化物酶基因(GPX1)cDNA全长序列。该序列全长890bp(GenBank accession No.EU828796),包括完全开放阅读框(ORF)576bp、5'非编码区(5'-UTR)17bp和3'-UTR297bp。其ORF编码191个氨基酸残基,包含一个由"UGA"(通常为终止密码子)编码的硒代半胱氨酸(selenocysteine,Sec40)残基,并与另2个残基(Glu75和Trp153)构成酶活性中心。同时,草鱼GPX1cDNA的3'-UTR中具有保守的硒代半胱氨酸插入序列(selenocysteine insertion sequence,SECIS)元件。氨基酸序列相似性比较显示,草鱼GPX1cDNA的推测氨基酸序列(GenBank accession No.ACF39780)与斑马鱼GPX1(GenBank accession No.NP_001007282)的相似性为95.8%,与鳗鲡GPX1(GenBank acces-sion No.ACN78878)的为84.8%,与哺乳类的为59%~72%。采用实时荧光定量PCR(Q-PCR)检测草鱼GPX1的组织表达特征。结果表明,草鱼GPX1的mRNA在所检测的11种组织器官中均有表达,其中在肝、鳃和肾表达水平较高,在红肌、脂肪和肠道中表达水平较低。本研究结果将有助于进一步探讨鱼类GPX1基因的结构与功能,并为研究其抗氧化分子机理奠定基础。  相似文献   

4.
植物过氧化物酶研究进展   总被引:128,自引:0,他引:128  
过氧化物酶 [peroxidase,POD,EC1 .1 1 .1 .7(X) ]是广泛存在于各种动物、植物和微生物体内的一类氧化酶。催化由过氧化氢参与的各种还原剂的氧化反应 :RH2 H2 O2 →2 H2 O R。植物过氧化物酶的研究可追溯到 1 80 9年用愈创树脂为底物进行的颜色反应。但直到一个世纪之后才开展此酶的分离和命名。已知的催化反应底物超过 2 0 0种 ,以及多种过氧化物和辅助因子。迄今被研究最深入的应首推辣根过氧化物酶 (horseradish pero-xidase,HRP)。早在 1 94 0年 ,Thorell即用电泳方法从部分纯化的辣根组织中区分出 2种不同的 HRP,之后此酶…  相似文献   

5.
目的 探索新的抗氧化剂.方法 研究萝卜过氧化物酶(POD)对小鼠肝、脾和肾脏超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GSH-Px)、丙二醛(MDA)的影响.结果 用不同剂量的POD处理后,可以提高肝、脾和肾的SOD、GSH-Px的活性,减低丙二醛的含量.结论 萝卜过氧化物酶可以提高机体的抗氧化能力.  相似文献   

6.
过氧化物酶广泛存在于各种有机体中,根据其结构和功能可分为不同的类型,其中ClassⅢ过氧化物酶是植物体内特有的一个多基因家族.ClassⅢ过氧化物酶的功能多样,能够参与生长素的代谢、细胞壁的延伸和加厚、活性氧和活性氮的代谢以及植物的抗病作用等各种生理活动.目前对ClassⅢ过氧化物酶的940个物种中的6 000条序列都已经进行了注释,包括其存在的物种、组织类型以及细胞中的定位等.该文对国内外近年来有关ClassⅢ过氧化物酶的结构特征及其在植物体内的功能等进行综述.  相似文献   

7.
动物抗氧化系统中主要抗氧化酶基因的研究进展   总被引:32,自引:0,他引:32  
抗氧化系统是机体清除体内多余的活性氧、保护自身免受氧化损伤的重要体系,其中超氧化物歧化酶、过氧化氢酶、谷胱甘肽过氧化物酶等起主要作用。本文将对动物抗氧化系统中,超氧化物歧化酶、过氧化氢酶和谷胱甘肽过氧化物酶基因的种类、分布、结构及表达进行综述。  相似文献   

8.
植物谷胱甘肽过氧化物酶(glutathione peroxidase,GPX)是清除体内活性氧的一种关键酶,在植物抗逆反应中发挥重要作用.本研究从水稻中克隆到2个GPX基因,分别为OsGPX3和OsGPX4.OsGPX3和OsGPX4分别编码238和234个氨基酸组成的蛋白质,预测分子量分别是25.84 kD和25.07 kD.两个基因都包含5个内含子,但是两个基因所对应的内含子长度具有较大变异.组织表达谱分析发现这2个基因在根、茎、叶和叶鞘中均表达,是组成型表达基因.在大肠杆菌中表达并纯化了这2个基因的重组蛋白,酶活性分析显示OsGPX3和OsGPX4蛋白对底物H2O2、tBOOH和COOH具有较高活性,但是OsGPX3对3种底物的活性均高于OsGPX4,蛋白质酶活性的差异预示着这2个基因可能存在功能上的分化.  相似文献   

9.
谷胱甘肽过氧化物酶(glutathione peroxidase, GPX)是动植物体内一种重要的抗氧化酶,它能够清除机体逆境胁迫而产生的过氧化氢和脂质过氧化物,使机体进行正常生长发育,因此解析丹参GPX的氨基酸序列,并与其它植物进行比较,为丹参GPX基因的后续研究提供重要参考。采用生物信息学的方法,在丹参基因组库中找到8个GPX基因,并对其进行生物信息学分析。8个GPX基因有不同的等电点和相对分子量,而二级结构存在相似特征;序列比对与系统发生分析表明,8个基因都具有3个保守结构域以及3个保守的催化残基;除Sm GPX4、At GPX4和Zm GPX02,Sm GPX8与At GPX8处于系统进化树的同一分支外,其它基因与玉米和拟南芥GPX基因的亲缘关系较远;Sm GPX1-2、Sm GPX6-1、Sm GPX6-2、Sm GPX8主要在叶片中表达,而Sm GPX1-1主要在花中表达,具有组织特异性。本研究为进一步了解丹参谷胱甘肽过氧化物酶的基本功能奠定了基础,为开展植物抵御氧化胁迫研究提供了理论依据。  相似文献   

10.
谷胱甘肽过氧化物酶(glutathione peroxidases,GPXs)是抗氧化酶系的重要成员之一,这些酶促进过氧化氢代谢,保护细胞膜结构和功能免受氧化损伤。其中,GPX8是最新发现的家族成员,它位于内质网中,是一种非特异性的抗氧化酶。GPX8的基因突变以及对DNA甲基化的影响都与肿瘤的发生密切相关。GPX8在多种肿瘤组织中异常表达,影响肿瘤的免疫微环境,在肿瘤的迁移和侵袭等方面具有重要的调节作用。但到目前为止GPX8在肿瘤中作用机制的研究甚少,为了更加全面地了解GPX8在肿瘤中的作用,本文对GPX8在胶质细胞瘤、胃癌和浸润性乳腺癌等多种肿瘤中的调控机制,以及其在临床患者治疗和预后评估中的作用进行了详细地综述。同时,本文阐述了GPX8在肾透明细胞癌、肝细胞癌和胰腺癌中近几年的最新研究进展。本文不仅概括了GPX8的研究现状,也总结了研究的不足,旨在为进一步深入研究GPX8在肿瘤中的调节机制以及临床寻找新的靶向治疗方法提供有利的理论基础。  相似文献   

11.
Plant glutathione peroxidases   总被引:22,自引:0,他引:22  
Oxidative stress in plants causes the induction of several enzymes, including superoxide dismutase (EC 1.15.1.1), ascorbate peroxidase (EC 1.11.1.11) and glutathione reductase (EC 1.6.4.2). The first two are responsible for converting superoxide to H2O2 and its subsequent reduction to H2O, and the third is involved in recycling of ascorbate. Glutathione peroxidases (GPXs, EC 1.11.1.9) are a family of key enzymes involved in scavenging oxyradicals in animals. Only recently, indications for the existence of this enzyme in plants were reported. Genes with significant sequence homology to one member of the animal GPX family, namely phospholipid hydroperoxide glutathione peroxidase (PHGPX), were isolated from several plants. Cit-SAP, the protein product encoded by the citrus csa gene, which is induced by salt-stress, is so far the only plant PHGPX that has been isolated and characterized. This protein differs from the animal PHGPX in its rate of enzymatic activity and in containing a Cys instead of selenocysteine (Sec) as its presumed catalytic residue. The physiological role of Cit-SAP and its homologs in other plants is not yet known.  相似文献   

12.
Abstract

The present investigation was carried out with the objectives to understand the effect of paclobutrazol, gibberellic acid and Pseudomonas fluorescens on the enzymatic antioxidants like Ascorbate peroxidase (APX, EC: 1.11.1.11), Superoxide dismutase (SOD, EC: 1.15.1.1), Catalase (CAT, EC: 1.11.1.6), Peroxidase (POX, EC 1.11.1.7) and polyphenol oxidase (PPO, Ec 1.10.3.1) activities of Catharanthus roseus plants under field conditions. 10 mg l?1 paclobutrazol, 5 µM gibberellic acid and 1 mg P. fluorescens concentrations were used for the treatments, and control plants were irrigated with well water. The treatments were given 38, 53, 68 and 83 days after planting (DAP) by soil drenching. The plants were taken randomly 45, 60, 75 and 90 DAP and separated into root, stem, leaves and flowers and used for estimating the antioxidant enzymes. The results showed that these plant growth regulators have significant effects on antioxidant enzymes of C. roseus.  相似文献   

13.
In order to examine whether polyamines (PAs) modify the functioning of the scavenging system and oxidative stress levels in water-stressed plants, cucumber (Cucumis sativus L.) seedlings were treated with spermidine (Spd) prior to dehydration, and stress-evoked changes in superoxide dismutase (SOD) (EC 1.15.1.1), catalase (EC 1.11.1.6), guaiacol peroxidase (EC 1.11.1.7) activities, H(2)O(2) and superoxide radical levels were determined. Free PA content during Spd treatment and during the stress period were also determined. Exogenous application of Spd differentially influenced enzymes of the antioxidative system under stress conditions; we observed an increase of guaiacol peroxidase activity, and, to a lesser degree, a reduction of SOD and catalase activities in Spd-treated plants in comparison to untreated stressed plants. Hydrogen peroxide and superoxide radical contents were also reduced in stressed plants after Spd pretreatment. These positive effects were observed in the case of 1mM Spd concentration. A higher concentration (3mM) influenced negative, more significant stress-induced changes, but a lower concentration (0.1mM) had a very limited effect. In summary, PAs are able to moderate the activities of scavenging system enzymes and to influence oxidative stress intensity.  相似文献   

14.
Ascorbate peroxidase,a haem protein (EC 1.11.1.11),efficiently scavenges hydrogen peroxide (H2O2) in cytosol and chloroplasts of plants.In this study,a fulllength coding sequence of thylakoid-bound ascorbate peroxidase cDNA (TatAPX) was cloned from a drought tolerant wheat cultivar C306.Homology modeling of the TatAPX protein was performed by using the template crystal structure of chloroplastic ascorbate peroxidase from tobacco plant (PDB: 1IYN).The model structure was further refined by molecular mechanic...  相似文献   

15.
A number of plant species are thought to possess a glutathione S-transferase enzyme (GST: EC 2.5.1.18) that will conjugate glutathione (GSH) to trans -cinnamic acid (CA) and para -coumaric acid (4-CA). However, we present evidence that this activity is mediated by peroxidase enzymes and not GSTs. The N-terminal amino acid sequence of the GSH-conjugating enzyme purified from etiolated corn shoots exhibited a strong degree of homology to cytosolic ascorbate peroxidase enzymes (APX: EC 1.11.1.11) from a number of plant species. The GSH-conjugating and APX activities of corn could not be separated during chromatography on hydrophobic-interaction. anion-exchange, and gel filtration columns. Spectral analysis of the enzyme revealed that the protein had a Soret band at 405 nm. When the enzyme was reduced with dithionite, the peak was shifted to 423 nm with an additional peak at 554 nm. The spectrum of the dithionite-reduced enzyme in the presence of 0.1 m M KCN exhibited peaks at 430, 534 and 563 nm. These spectra are consistent with the presence of a heme moiety. The GSH-conjugating and APX activities of the enzyme were both inhibited by KCN. NaN3, p -chloromercuribenzoate ( p CMB), and iodoacetate. The APX specific activity of the enzyme was 1.5-fold greater than the GSH-conjugating specific activity with 4-CA. In addition to the corn enzyme, a pea recombinant APX (rAPX) and horseradish peroxidase (HRP; EC 1.11.1.7) were also able to conjugate GSH to CA and 4-CA. The peroxidase enzymes may generate thiyl free radicals of GSH that react with the alkyl double bond of CA and 4-CA resulting in the formation of a GSH conjugate.  相似文献   

16.
Glutathione peroxidases (GPXs) are a group of enzymes that protect cells against oxidative damage generated by reactive oxygen species (ROS). The presence of GPXs in plants has been reported by several groups, but the roles of individual members of this family in a single plant species have not been studied. A family of seven related proteins named AtGPX1- AtGPX7 in Arabidopsis was identified, and the genomic organization of this family was reported. The putative subcellular localizations of the encoded proteins are the cytosol, chloroplast, mitochondria, and endoplasmic reticulum. Expressed sequence tags (ESTs) for all the genes except AtGPX7 were identified. Expression analysis of AtGPX genes in Arabidopsis tissues was performed, and different patterns were detected. Interestingly, several genes were up-regulated coordinately in response to abiotic stresses. AtGPX6, like human phospholipid hydroperoxide GPX (PHGPX), possibly encodes mitochondrial and cytosolic isoforms by alternative initiation. In addition, this gene showed the strongest responses under most abiotic stresses tested. AtGPX6::GUS analysis in transgenic Arabidopsis showed that AtGPX6 is highly expressed throughout development in most tissues, thus supporting an important role for this gene in protection against oxidative damage. The different effects of salicylic acid (SA), jasmonic acid (JA), abscisic acid (ABA), and auxin on the expression of the genes indicate that the AtGPX family is regulated by multiple signaling pathways. Analysis of the upstream region of the AtGPX genes revealed the presence of multiple conserved motifs, and some of them resembled antioxidant-responsive elements found in plant and human promoters. The potential regulatory role of specific sequences is discussed.  相似文献   

17.
The effect of leaf rust (Puccinia triticina) infection on intercellular chitinase (EC 3.2.1.14) and peroxidase (EC 1.11.1.7) activities was studied in resistant [RL 6082 (Thatcher/Lr35)] and susceptible (Thatcher) near isogenic wheat (Triticum aestivum L.) lines at seedling, stem elongation and flag leaf stages of plant growth. The levels of activity of these enzymes were low during the seedling and stem elongation stages. Resistant plants at the flag leaf stage, during which the Lr35 resistance gene was maximally expressed, exhibited high constitutive levels of chitinase and peroxidase activities, in contrast to the lower constitutive levels of susceptible plants. The results suggest that chitinase and peroxidase, constitutively present in the intercellular spaces of Thatcher/Lr35 wheat leaves, may play a role in Lr35 mediated resistance to leaf rust.  相似文献   

18.
Glutathione peroxidases (GPXs) are a group of enzymes that regulate the levels of reactive oxygen species in cells and tissues, and protect them against oxidative damage. Contrary to most of their counterparts in animal cells, the higher plant GPX homologues identified so far possess cysteine instead of selenocysteine in their active site. Interestingly, the plant GPXs are not dependent on glutathione but rather on thioredoxin as their in vitro electron donor. We have determined the crystal structures of the reduced and oxidized form of Populus trichocarpaxdeltoides GPX5 (PtGPX5), using a selenomethionine derivative. PtGPX5 exhibits an overall structure similar to that of the known animal GPXs. PtGPX5 crystallized in the assumed physiological dimeric form, displaying a pseudo ten-stranded beta sheet core. Comparison of both redox structures indicates that a drastic conformational change is necessary to bring the two distant cysteine residues together to form an intramolecular disulfide bond. In addition, a computer model of a complex of PtGPX5 and its in vitro recycling partner thioredoxin h1 is proposed on the basis of the crystal packing of the oxidized form enzyme. A possible role of PtGPX5 as a heavy-metal sink is also discussed.  相似文献   

19.
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