Drought-Stress-Induced Changes in Activities of Superoxide Dismutase, Catalase, and Peroxidase in Wheat Species

Activities of superoxide dismutase (SOD), catalase (CAT), andperoxidase (POD), as well as malondialdehyde (MDA) contentsand solute potentials, were studied in seedlings of seven wheat(Triticum) species (nine genotypes representing three ploidylevels: hexaploid, tetraploid, diploid) subjected to water stressfor 4, 8, and 12 days by withholding water. Solute potentialsof all genotypes were lowered by water stress. In most species,SOD and CAT activities showed an increase or maintenance inthe early phase of drought and then a decrease with furtherincrease in magnitude of water stress. On the contrary, PODactivities and MDA contents greatly increased in response towater stress. Enzymatic activities partly recovered and MDAcontents decreased with rewatering. Under drought, hexaploidwheats had higher POD activities and MDA contents than tetraploidand diploid wheats; solute potentials and activities of SODand CAT, however, were similar among the three groups. Theseresults suggest that water stress alters the equilibrium betweenfree radical production and enzymatic defense reactions in wheatspecies and that hexaploid wheats have less efficient antioxidantsystems (e.g., the ascorbate-glutathione cycle and the nonenzymaticsystem) than tetraploid and diploid wheats. (Received February 9, 1994; Accepted April 22, 1994)     

Superoxide Dismutase, Catalase, and Glutathione Peroxidase Activities in Copper/Zinc-Superoxide Dismutase Transgenic Mice

Copper/zinc-superoxide dismutase (CuZn-SOD) transgenic mice overexpress the gene for human CuZn-SOD. To assess the effects of the overexpression of CuZn-SOD on the brain scavenging systems, we have measured the activities of manganese-SOD (Mn-SOD), catalase, and glutathione peroxidase (GSH-Px) in various regions of the mouse brain. In nontransgenic mice, cytosolic CuZn-SOD activity was highest in the caudate-putamen complex; this was followed by the brainstem and the hippocampus. The lowest activity was observed in the cerebellum. In transgenic mice, there were significant increases of cytosolic CuZn-SOD activity in all of these regions, with ratios varying from a twofold increase in the brainstem to 3.42-fold in the cerebellum in comparison with nontransgenic mice. Particulate Mn-SOD was similarly distributed in all brain regions, and its levels also were significantly increased in superoxide dismutase (SOD)-transgenic mice. In the brains of nontransgenic mice, cytosolic catalase activity was similar in all brain regions except the cortex, which showed less than 50% of the activity observed in the other regions. In transgenic mice, cytosolic catalase activity was significantly increased, with the cortex showing the greatest changes (133%) in comparison with nontransgenic mice. The smallest increases were observed in the hippocampus (34%). In contrast to what was observed for SOD and catalase, there were no significant changes in cytosolic GSH-Px activity in any of the brain regions examined. The present results indicate that, in addition to displaying marked increases in the levels of brain CuZn-SOD activity, SOD-transgenic mice also exhibit increases in other enzymes that scavenge oxygen-based radicals.(ABSTRACT TRUNCATED AT 250 WORDS)     

Structural Evidence for a Copper-Bound Carbonate Intermediate in the Peroxidase and Dismutase Activities of Superoxide Dismutase

Copper-zinc superoxide dismutase (SOD) is of fundamental importance to our understanding of oxidative damage. Its primary function is catalysing the dismutation of superoxide to O₂ and H₂O₂. SOD also reacts with H₂O₂, leading to the formation of a strong copper-bound oxidant species that can either inactivate the enzyme or oxidise other substrates. In the presence of bicarbonate (or CO₂) and H₂O₂, this peroxidase activity is enhanced and produces the carbonate radical. This freely diffusible reactive oxygen species is proposed as the agent for oxidation of large substrates that are too bulky to enter the active site. Here, we provide direct structural evidence, from a 2.15 Å resolution crystal structure, of (bi)carbonate captured at the active site of reduced SOD, consistent with the view that a bound carbonate intermediate could be formed, producing a diffusible carbonate radical upon reoxidation of copper. The bound carbonate blocks direct access of substrates to Cu(I), suggesting that an adjunct to the accepted mechanism of SOD catalysed dismutation of superoxide operates, with Cu(I) oxidation by superoxide being driven via a proton-coupled electron transfer mechanism involving the bound carbonate rather than the solvent. Carbonate is captured in a different site when SOD is oxidised, being located in the active site channel adjacent to the catalytically important Arg143. This is the probable route of diffusion from the active site following reoxidation of the copper. In this position, the carbonate is poised for re-entry into the active site and binding to the reduced copper.     

Ascorbic Acid-Dependent Regulation of Redox Levels of Chlorogenic Acid and its Isomers in the Apoplast of Leaves of Nicotiana tabacum L.

There is a question whether ascorbic acid (AA) can control redoxlevels of phenolics in the apoplast. The present study was designedto answer this question. AA, dehydroascorbic acid (DHA), chlorogenicacid (CGA) and its two structural isomers were present in theapoplast of leaves of tobacco (Nicotiana tabacum L. cv. BelW3).The levels of AA plus DHA (AA + DHA) and the ratios of AA to(AA + DHA) decreased while the levels of CGA plus its isomersincreased during leaf aging. o-Quinones of CGA plus its isomerswere found in the apoplast only in aged leaves of which apoplasticlevel of AA was nearly zero. In addition, activity of apoplasticperoxidase that could oxidize CGA and its isomers increasedduring leaf aging. From the observations, it is concluded thatAA can regulate the accumulation of the o-quinones of CGA andits isomers in the apoplast. Based on the conclusion, it isproposed that soluble peroxidase in the apoplast has two functions,namely, (i) scavenging of H₂O₂ and/or regulation of the levelof apoplastic H₂O₂ in the presence of AA, and (ii) accumulationof oxidation products of the phenolics in the absence of AA. (Received January 30, 1998; Accepted April 7, 1998)     

Coimmobilization of Superoxide Dismutase,Catalase, and Peroxidase

Various orders of sequential coimmobilization of superoxide dismutase (SOD), catalase, and horseradish peroxidase (HRP) were tested in order to prepare a multienzyme antioxidant complex of these enzymes. Simultaneous coimmobilization of catalase with a preliminarily cross-linked complex between SOD and HRP was found to be the optimum procedure. The catalytic enzyme activity and working stability of catalase was tested kinetically in the multienzyme complexes prepared by different methods. The effects of ascorbic acid, glutathione, and ethanol on the kinetic parameters of catalase were studied. A possible scheme of H₂O₂ degradation catalyzed by coimmobilized SOD, catalase, and HRP in the presence of reducing substrates is suggested.     

脱氧核糖核酸对机体内超氧化物岐化酶和过氧化物酶活性影响初步研究

超氧化物岐化酶（SOD）和过氧化物酶（POD）是机体内重要的抗氧化酶系之一,其作用在于消除体内的自由基,防止自由基对细胞结构的损伤。它们的活性随增龄而下降,因此自由基不断损伤细胞结构,累积最终导致细胞衰亡和动物机体衰老,老龄小鼠服用DNA一段时间后,其体内SOD和POD的活性均显著提高,因而其衰老速度可能得到一定程度的延缓。     

The Role of Indole-3-Acetic Acid in Peroxidase Oxidation of Ascorbic Acid Catalyzed by Horseradish Peroxidase

We studied stationary kinetics of ascorbic acid oxidation in the presence of indole-3-acetic acid catalyzed by horseradish peroxidase. The catalytic (k_cat and K_m) and inhibition (K_i) constants were determined for pH from 4.5 to 7.0. The auxin proved to competitively inhibit the enzyme when a single ascorbic acid molecule is bound, while a non-competitive inhibition by IAA is observed for peroxidase oxidation of two or more substrate molecules. A mechanism of ascorbic acid oxidation in the presence of indole-3-acetic acid is proposed.     

Enhancement of Peroxidase, Polyphenol Oxidase and Superoxide Dismutase Activities by Triadimefon in NaCl Stressed Raphanus Sativus L.

The activities of peroxidase, polyphenol oxidase and superoxide dismutase was significantly lower in roots and leaves of NaCl stressed radish (Raphanus sativus L.) plants. Addition of triadimefon to the NaCl stressed plants increased peroxidase, polyphenol oxidase and superoxide dismutase activities, and thereby ameliorated the negative effect of NaCl stress.     

Changes in Expression of Manganese Superoxide Dismutase,Copper and Zinc Superoxide Dismutase and Catalase in Brachionus calyciflorus during the Aging Process

Rotifers are useful model organisms for aging research, owing to their small body size (0.1–1 mm), short lifespan (6–14 days) and the relative easy in which aging and senescence phenotypes can be measured. Recent studies have shown that antioxidants can extend the lifespan of rotifers. In this paper, we analyzed changes in the mRNA expression level of genes encoding the antioxidants manganese superoxide dismutase (MnSOD), copper and zinc SOD (CuZnSOD) and catalase (CAT) during rotifer aging to clarify the function of these enzymes in this process. We also investigated the effects of common life-prolonging methods [dietary restriction (DR) and resveratrol] on the mRNA expression level of these genes. The results showed that the mRNA expression level of MnSOD decreased with aging, whereas that of CuZnSOD increased. The mRNA expression of CAT did not change significantly. This suggests that the ability to eliminate reactive oxygen species (ROS) in the mitochondria reduces with aging, thus aggravating the damaging effect of ROS on the mitochondria. DR significantly increased the mRNA expression level of MnSOD, CuZnSOD and CAT, which might explain why DR is able to extend rotifer lifespan. Although resveratrol also increased the mRNA expression level of MnSOD, it had significant inhibitory effects on the mRNA expression of CuZnSOD and CAT. In short, mRNA expression levels of CAT, MnSOD and CuZnSOD are likely to reflect the ability of mitochondria to eliminate ROS and delay the aging process.     

Parameters of Metabolic Syndrome and Its Relationship with Zincemia and Activities of Superoxide Dismutase and Glutathione Peroxidase in Obese Women

Alterations in antioxidant defense in obese people with metabolic syndrome can contribute to oxidative stress. This study assessed the relationship between the parameters of metabolic syndrome and the zincemia, activity of superoxide dismutase, and glutathione peroxidase enzymes in obese women. Seventy-three premenopausal women, aged between 20 and 50 years, were divided into two groups: case group, composed of obese (n = 37), and control group, composed of no obese (n = 36). Analyses of zinc intake, parameters of metabolic syndrome, plasma, and erythrocyte zinc, and activities of superoxide dismutase and glutathione peroxidase were carried out. The mean values of body mass index of obese women and control group were 34.5 ± 3.4 and 21.7 ± 1.9 kg/m², respectively (p < 0.05). In the study, body mass index, waist circumference, and zinc intake were higher in obese women than control group (p < 0.05). The plasma zinc and activity of superoxide dismutase did not show significant differences between obese and controls (p > 0.05). The values of erythrocyte zinc was 36.4 ± 15.0 μg/gHb and 45.4 ± 14.3 μg/gHb and of glutathione peroxidase was 46.4 ± 19.4 U/gHb and 36.7 ± 13.6 U/gHb in obese women and controls, respectively (p < 0.05). The study shows that there are alterations in biochemical parameters of zinc in obese women, with low zinc concentrations in erythrocytes. Regression analysis demonstrates that the erythrocyte zinc and activity of superoxide dismutase enzyme is influenced by components of the metabolic syndrome, and the plasmatic glucose, body mass index, and waist circumference have a negative correlation with this enzyme.     

Age-Dependent Resistance to the Toxic Effects of Paraquat in Relation to Superoxide Dismutase Activity in Rat Lung

Young rats are much more resistant to the toxic effects of orally-administered paraquat than are older rats. The possible relation of this phenomenon to the activity of superoxide dismutase in lung is discussed.     

CuZn-Superoxide Dismutase, Extracellular Superoxide Dismutase, and Glutathione Peroxidase in Blood from Individuals Homozygous for Asp90Ala CuZn-Superoxide Dismutase Mutation

Abstract: The Asp⁹⁰Ala CuZn-superoxide dismutase mutation is associated with amyotrophic lateral sclerosis (ALS) in both homo- and heterozygous form. We analyzed antioxidant enzymes in blood from 44 individuals homozygous and 114 individuals heterozygous for the Asp⁹⁰Ala mutation as well as 66 blood relatives carrying the wild-type allele only. Erythrocyte CuZn-superoxide dismutase activity was reduced by 9% in the homozygous individuals, confirming previous findings on a smaller cohort. The specific activity of Asp⁹⁰Ala mutant CuZn-superoxide dismutase in erythrocytes was equal to that of isolated mutant enzyme and slightly higher than that of isolated wild-type enzyme. There was no evidence for the presence of inactive mutant molecules in erythrocytes, and the lower activity is due to the occurrence of fewer active molecules. There were no significant differences between the groups in plasma extracellular superoxide dismutase content, and the erythrocyte glutathione peroxidase activities were virtually identical. Also, there were no differences in these parameters between homozygous individuals with or without ALS. There was no evidence for any association with ALS of a polymorphic extracellular superoxide dismutase mutation, Arg²¹³Gly. The absence of response of the blood antioxidant enzymes to the Asp⁹⁰Ala CuZn-superoxide dismutase mutation does not support the theory that the ALS-linked CuZn-superoxide dismutase mutations cause disease by increased oxidant stress.     

陆地棉超氧化物歧化酶基因的克隆与烟草转化

以陆地棉‘中棉所36’和烟草‘NC89’为材料,采用RT-PCR方法,从陆地棉中克隆到了Cu/Zn-SOD的cD-NA编码区,经植物表达载体pBI-SOD,导入根癌农杆菌LBA4404,对烟草叶片进行遗传转化,经卡那霉素筛选,获得正确的Cu/Zn-SOD的cDNA编码区,构建了转基因载体,并成功地获得2株转基因烟草;经PCR、Southern blotting和SOD酶活性等检测,证明Cu/Zn-SOD基因已经整合到烟草的基因组并表达。本试验结果为转基因棉花的进一步研究奠定了基础。     

A Possible Mechanism for the Oxidation of Sinapyl Alcohol by Peroxidase-Dependent Reactions in the Apoplast: Enhancement of the Oxidation by Hydroxycinnamic Acids and Components of the Apoplast

Apoplastic peroxidase isoenzymes from stems of Nicotiana tabacumrapidly oxidized sinapic acid and sinapyl alcohol, in additionto 4-coumaric acid, ferulic acid and coniferyl alcohol. By contrast,the peroxidase isoenzymes from stems of Vigna angularis oxidizedsinapic acid and sinapyl alcohol quite slowly but rapidly oxidizedcompounds with a 4-hydroxyphenyl or a guaiacyl group. However,the oxidation of sinapyl alcohol was greatly enhanced by 4-coumaricacid, ferulic acid and an ester of ferulic acid. Intercellularwashing fluid of V. angularis, which contained apoplastic components,also enhanced the oxidation of sinapyl alcohol. Based on theseresults, a possible mechanism for the oxidation of sinapyl alcoholis discussed on the assumption that the biosynthesis of ligninproceeds mainly via peroxidases which cannot oxidize sinapylalcohol in V. angularis. (Received October 23, 1995; Accepted April 3, 1996)     

Peroxide Levels and the Activities of Catalase, Peroxidase, and Indoleacetic Acid Oxidase during and after Chilling Cucumber Seedlings

The activities of catalase, peroxidase, indoleacetic acid (IAA) oxidase and peroxide levels in cucumber plants during and after chilling were determined. During 96 hours at 5 C and 85% relative humidity, catalase activity declined, IAA oxidase activity increased, and peroxide concentrations increased. Peroxidase activity was not affected by chilling. When chilled plants were returned to 25 C to recover, enzyme activities and peroxide concentration were restored to their prechilling levels. The increase in peroxide and IAA oxidase activity may inactivate or destroy IAA and thus retard growth.     

Activities of Antioxidant Scavenger Enzymes (Superoxide Dismutase and Glutathione Peroxidase) in Erythrocytes in Adult Women With and Without Type II Diabetes

It is widely believed that oxidative stress plays an important role in the pathogenesis of type II diabetes. The present study was undertaken to examine the functioning of two antioxidant scavenger enzymes, superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), in erythrocytes in a population of healthy aging adult women compared with a similar population with type II diabetes. Blood samples were examined from 42 female adult healthy subjects at different ages and from 59 female patients with type II diabetes. A significant increase in SOD activities was correlated with aging in erythrocytes of the healthy control subjects (r = .550, P = .001); however, this correlation was not found in subjects with type II diabetes (r = .250, P < .07). A trend showing a reduction in glutathione peroxidase activities was demonstrated with aging (r = −.331, P = .228); however, this trend was not found in diabetic subjects (r = .031, P < .820). The results indicate a possible imbalance in the antioxidant system in erythrocytes of aging adult women, which is even more pronounced in cases of type II diabetes. This study may indicate possible therapeutic treatment or preventive measures to limit oxidative damage and reduce complications of diabetes.     

Changes in Superoxide Dismutase Activity in Liver and Lung of Old Rats

Superoxide dismutase activity was measured in liver and lung from 3 and 24 month-old rats. Both total SOD and Mn-SOD activity decreased significantly in the liver of old rats. Recent results from our laboratory have indicated that during aging, the activity of Cu/Zn-SOD decreases in rat liver and that there is an accumulation of altered protein. It was also shown that the old Cu/Zn-SOD had one histidine fewer than the young one. In the present study, the immunoprecipitation experiments showed that the amount of immunoprecipitable Mn-SOD from liver of old rats was greater than from young ones, but when amino acid residues were measured in purified young and old Mn-SOD from liver, no change was observed. In lung, no significant age-related differences in total SOD, Cu/Zn-SOD and Mn-SOD activity were found, nor was there accumulation of altered protein during aging.