Native Sod Research Articles

Native grass sod and plug production as an alternative technique to restore neotropical rupestrian grassland after mining

Despite the importance of grasses in the structure and functioning of tropical grasslands, there is still a lack of efficient and economically viable techniques to produce and introduce grasses in restoration projects. Here, we evaluated the sod and plug‐plant production and planting of a native grass from Brazilian rupestrian grasslands, Sporobolus metallicolus, in a post‐bauxite mining. To produce the sod, we used post‐mining substrate and its mixture with commercial substrate. Then, we sowed 270 seeds of S. metallicolus on a 4‐cm layer of substrate in 144‐cm2 trays. Eighty days after sowing, we subdivided the contents of each tray (substrate + plant) into 4 × 3–cm plug‐plants. Plug‐plants were planted in the degraded area with and without the incorporation of litter from an adjacent conserved rupestrian grassland. We also evaluated the cost of production of each plug‐plant. The mixture of substrates provided greater plant growth and rooting, obtaining plug‐plants with an average of 13 individuals, dry mass of 270 mg, and estimated cost of US$ 0.0045. In the degraded area, the addition of litter increased shoot biomass gain. Plant survival was 100% with and without litter addition and the plants started seed dispersal at 7 months after planting. The production of S. metallicolus plugs with the mixed substrate and the growth of plants in the post‐mined area showed promising results and reduced costs, indicating technical and financial feasibility. The presented techniques can be an option for introducing grasses in degraded areas and optimize the use of seeds.

Two versatile salicylatocopper(II) complexes: Structure, spectral, magnetic, electrochemical properties and SOD mimetic activity

Two new salicylatocopper(II) complexes of formula [Cu(3-Mesal)2(inia)2]21 and [Cu(4-MeOsal)2(H2O)]·H2O 2, (where 3-Mesal = 3-methylsalicylate, inia = isonicotinamide, 4-MeOsal = 4-methoxylsalicylate) have been studied in solid state or in solutions. The coordination environment of compound 1 differs from complex 2, but both compounds build up 2-D supramolecular framework. The spectral and magnetic properties are in good agreement to their structure. Moreover, the cyclic voltammetric study, as well as the superoxide dismutase activity of prepared complexes has been studied in solution by NBT assay, and compared with the activity of the parent ligand, copper acetate and native SOD enzyme. SOD mimetic activity of the prepared compounds exhibited rather different IC50 values for compound 1 and 2. The SOD activity together with the redox stability is related to the composition and structure of the complexes.

Preserving native grassland: Can Sodsaver reduce cropland conversion?

Native grassland or “native sod”—grassland that has never been tilled for crop production—can provide high-quality habitat for a number of species, including grassland birds, breeding waterfowl, and pollinators. Much of the grassland that once dominated the Midwest and Plains states between the Mississippi River and the Rocky Mountains has already been lost or severely fragmented, reducing its value as habitat (Connor et al. 2002). Once lost, these grasslands are difficult and costly to restore (Loesch et al. 2012). In recent years, attention to the loss of grassland in the northern Great Plains, particularly in the Prairie Pothole Region (PPR), has grown as a number of researchers have documented the conversion of grass to crop production (Wright and Wimberly 2013; Larkin et al. 2015; Doherty et al. 2013), although data used in these studies do not distinguish native sod from other grasslands.

Synthesis, spectral, magnetic properties, electrochemical evaluation and SOD mimetic activity of four mixed-ligand Cu(II) complexes

Four new methylsalicylato copper(II) complexes with formula [Cu(4-Mesal)2(2-Meim)2] (1), [Cu(4-Mesal)2(im)2] (2), [Cu(3-Mesal)2(bzim)2]·2H2O (3), [Cu(5-Mesal)2(im)2]n (4) (where 3-Mesal−=3-methylsalicylato, 4-Mesal−=4-methylsalicylato, 5-Mesal−=5-methylsalicylato anion, im=imidazole, 2-Meim=2-methylimidazole and bzim=benzimidazole) are reported. The solid state complexes were characterized by IR, UV–Vis, EPR, X-ray and magnetic measurements. Despite common coordination environment {CuO2N2O′2} different supramolecular structures were found for the compounds: 1 is a 1-D supramolecular chain, 2 and 3 form 2-D supramolecular networks and 4 is a 1D coordination polymer. The superoxide dismutase-like (SOD-like) activity of complexes 1–4 was studied in solution by NBT assay, compared with the activity of the parent ligand, copper acetate and native SOD enzyme and correlated to the redox stability determined by cyclic voltammetry. The exceptionally low SOD-like activity of 3, its lower redox reversibility and higher electron-withdrawing ability could be related to the lowest axial distortion of its coordination environment.

Tussock and sod tussock grasslands of the New England Tablelands Bioregion of eastern Australia

We surveyed temperate montane natural grasslands across the New England Tablelands Bioregion (NETB) and assessed the phytosociology, occurrence and threats to these assemblages. In total, 123 full floristic survey plots were placed within natural grasslands across the NETB. Mapping was undertaken within a subset of the NETB using ADS40 imagery. Analysis of the floristic data was performed using the Kulzynski association measure and UPGMA fusion strategy. Canonical correspondence analysis was performed with species data in association with 42 environmental variables. An estimated 25 000 ha of native tussock and sod tussock grasslands within six floristic assemblages were found within the NETB. The maximum extent of predicted high-quality stands may only be 2500 ha with most occurrences degraded and threatened by agricultural practices, exotic species and changes in above- and below-ground water resources. Native taxa were significantly associated with altitude, rock type and differential temperature tolerances. Altitude, eastness (longitude) and radiation of the wettest period were significant drivers of exotic species occurrence.

Nanoformulated copper/zinc superoxide dismutase attenuates vascular cell activation and aortic inflammation in obesity

ObjectiveEndothelial cell (EC) oxidative stress can lead to vascular dysfunction which is an underlying event in the development of cardiovascular disease (CVD). The lack of a potent and bioavailable anti-oxidant enzyme is a major challenge in studies on antioxidant therapy. The objective of this study is to determine whether copper/zinc superoxide dismutase (CuZnSOD or SOD1) after nanoformulation (nanoSOD) can effectively reduce EC oxidative stress and/or vascular inflammation in obesity. Methods. Human aortic endothelial cells (HAECs) were treated with native- or nanoSOD for 6 h followed by treatment with linoleic acid (LA), a free fatty acid, for 6–24 h. To determine the in vivo relevance, the effectiveness of nanoSOD in reducing vascular cell activation was studied in a mouse model of diet-induced obesity. Results. We noted that nanoSOD was more effectively taken up by ECs than native SOD. Western blot analysis further confirmed that the intracellular accumulation of SOD1 protein was greatly increased upon nanoSOD treatment. Importantly, nanoSOD pretreatment led to a significant decrease in LA-induced oxidative stress in ECs which was associated with a marked increase in SOD enzyme activity in ECs. In vivo studies showed a significant decrease in markers of EC/vascular cell activation and/or inflammation in visceral adipose tissue (VAT), thoracic aorta, and heart collected from nanoSOD-treated mice compared to obese control mice. Interestingly, the expression of metallothionein 2, an antioxidant gene was significantly increased in nanoSOD-treated mice. Conclusion. Our data show that nanoSOD is very effective in delivering active SOD to ECs and in reducing EC oxidative stress. Our data also demonstrate that nanoSOD will be a useful tool to reduce vascular cell activation in VAT and aorta in obesity which, in turn, can protect against obesity-associated CVD, in particular, hypertension.

NanoSOD reduces adipose tissue inflammation in obesity (1107.10)

Obesity‐linked hypertension is resistant to antihypertensive drugs and, adipose tissue (AT) inflammation is considered to mediate the pathological consequences of obesity. The objective of this study is to determine the effectiveness of nanoformulated copper/zinc superoxide dismutase (nanoSOD) in reducing AT inflammation in obesity. Wild type mice were fed a high fat (HF) diet (45% fat) for 8 or 13 wk followed by 2 wk treatment with native or nanoSOD. The drug uptake studies showed that nanoSOD was accumulated in the visceral AT to a greater extent than native SOD in obese mice. The mice fed a HF diet for 8 wk followed by 2 wk treatment with nanoSOD showed an increase in SOD content in stromal vascular cells (SVCs) collected from AT and in the plasma. These mice also showed a reduction in nitrotyrosine level, a marker of superoxide induced oxidative stress, in SVCs. The AT inflammatory markers showed a trend towards a decrease. The serum toxicity markers did not alter in nanoSOD compared to other groups suggesting that the nanoSOD is safe to use in vivo. After 13 wk on a HF diet followed by 2 wk treatment, the SVCs derived from AT of nanoSOD treated mice showed a decrease in the mRNA levels of MCP‐1 and MIP‐1α. Also, the MCP‐1 mRNA and protein levels in total AT was reduced to a greater extent in nanoSOD compared to native SOD treated mice. Our data suggest that nanoSOD may be a potential therapeutic agent to ameliorate obesity‐linked cardiovascular risk factors, in particular, systemic hypertention.Grant Funding Source: National Institutes of Health (NIH‐NIGMS)

Liposome-encapsulated superoxide dismutase mimetic: theranostic potential of an MR detectable and neuroprotective agent.

Endogenous manganese based superoxide dismutase (Mn-SOD) provides the primary defense against excess production of potentially toxic superoxide anion (O2 (-) ). M40401 is a synthetic enzyme mimetic that has a catalytic activity rate exceeding that of the native SOD enzymes. The presence of a paramagnetic Mn(II) cation in M40401 suggests that the delivery and spatial distribution of this enzyme mimetic in vivo may be directly detectible using magnetic resonance imaging (MRI); however, the cardiotoxicity of Mn(II) severely limits the use of free M40401 in living systems. To deliver M40401 in vivo in amounts sufficient for MRI detection and to limit potential cardiotoxicity, we encapsulated M40401 into 170 nm liposomes composed of phosphatidylcholine and PEGylated phosphatidylethanolamine to achieve extended circulation in the bloodstream. The obtained liposomes efficiently catalyzed superoxide dismutation in vitro. Using 3 T MRI we investigated the biokinetics of liposome-encapsulated M40401 in mice and found that, in addition to catalyzing superoxide dismutation in vitro, M40401 caused differential and region-specific enhancement of mouse brain after systemic administration. Thus, liposome encapsulated M40401 is an ideal candidate for development as a theranostic compound useful for simultaneous MRI-mediated tracking of delivery as well as for neuroprotective treatment of ischemic brain.

Greenhouse gas fluxes of grazed and hayed wetland catchments in the U.S. Prairie Pothole Ecoregion

Wetland catchments are major ecosystems in the Prairie Pothole Region (PPR) and play an important role in greenhouse gases (GHG) flux. However, there is limited information regarding effects of land-use on GHG fluxes from these wetland systems. We examined the effects of grazing and haying, two common land-use practices in the region, on GHG fluxes from wetland catchments during 2007 and 2008. Fluxes of methane (CH4), nitrous oxide (N2O), and carbon dioxide (CO2), along with soil water content and temperature, were measured along a topographic gradient every other week during the growing season near Ipswich, SD, USA. Closed, opaque chambers were used to measure fluxes of soil and plant respiration from native sod catchments that were grazed or left idle, and from recently restored catchments which were seeded with native plant species; half of these catchments were hayed once during the growing season. Catchments were adjacent to each other and had similar soils, soil nitrogen and organic carbon content, precipitation, and vegetation. When compared with idle catchments, grazing as a land-use had little effect on GHG fluxes. Likewise, haying had little effect on fluxes of CH4 and N2O compared with non-hayed catchments. Haying, however, did have a significant effect on combined soil and vegetative CO2 flux in restored wetland catchments owing to the immediate and comprehensive effect haying has on plant productivity. This study also examined soil conditions that affect GHG fluxes and provides cumulative annual estimates of GHG fluxes from wetland catchment in the PPR.

Evaluation of California Native Grass Species for Sod Development

The objective of this research was to develop and demonstrate native grass sod for sediment control from disturbed lands associated with California highways. The research evaluated native grass species for inclusion in sod and evaluated the sod at a California highway field site. Seed mixes, including rhizomatous and bunchgrass species, were evaluated in a greenhouse setting for six California ecoregions. Growth and sod development potential of each seed mix for each ecoregion were evaluated. Seed mixes for three California ecoregions were further evaluated with a reinforcement material, and for establishment and weed suppression. Establishment and weed suppression of select ecoregion seed mixes and reinforcement materials were evaluated. Results indicated that multispecies sod has potential for use in revegetation of disturbed lands associated with highways.

Using yeast models to probe the molecular basis of amyotrophic lateral sclerosis

ALS (amyotrophic lateral sclerosis) is a fatal neurodegenerative disease attributable to the death of motor neurons. Associated with ALS are mutations in the genes encoding SOD1 (superoxide dismutase 1), FUS (fused in Sarcoma) protein and TDP-43 (TAR DNA-binding protein-43) each of which leads to aggregation of the respective protein. For example, the ALS-associated mutations in the hSOD1 (human SOD1) gene typically destabilize the native SOD homodimer, leading to misfolding, aggregation and degradation of SOD1. The ALS-associated pathology is not a consequence of the functional inactivation of SOD1 itself, but is rather due to a toxic gain-of-function triggered by mutant SOD1. Recently, the molecular basis of a number of human neurodegenerative diseases resulting from protein misfolding and aggregation, including fALS (familial ALS), was probed by using the baker's yeast, Saccharomyces cerevisiae, as a highly tractable model. Such studies have, for example, identified novel mutant SOD1-specific interactions and demonstrated that mutant SOD1 disrupts mitochondrial homoeostasis. Features of ALS associated with TDP-43 aggregation have also been recapitulated in S. cerevisiae including the identification of modulators of the toxicity of TDP-43. In this paper, we review recent studies of ALS pathogenesis using S. cerevisiae as a model organism and summarize the potential mechanisms involved in ALS progression.

Construction of a Hyperbranched Supramolecular Polymer as a Bifunctional Antioxidative Enzyme Model

A HBSP has been designed as a novel bifunctional enzyme model with SOD and GPx activity by host/guest-directed self-assembly of MnTPyP-M-Ad and 6-Te-diCD. The structure of the host/guest complex was elucidated by (1) H NMR spectra, and the HBSP was characterized by SEM, DLS and measurement of catalytic properties. In the bifunctional enzyme model, the Mn(III) porphyrins act as efficient SOD active sites and the tellurol moieties endow GPx activity. The SOD-like activity (IC(50) ) of this new supramolecular catalyst was found to be 1.05 × 10(-7) M, which corresponds to 2.82% of the activity of the native SOD enzyme. Besides this, the hyperbranched supramolecular polymer also shows a higher GPx activity (ν(0 ) = 21.7 × 10(-6) M · min(-1) ) than other supramolecular enzyme models.

Developing Native Multispecies Sod: An Alternative Rehabilitation Method for Disturbed Lands

Natural and anthropogenic disturbance provides a mechanism for resetting the species assemblage within natural communities. Following anthropogenic disturbance particularly, there are generally more weedy species. Restoration of ecosystem structure and function in disturbed areas could aid in the control of these undesirable species. Attempts to re‐establish vegetation via direct sowing, hydroseeding, drill seeding, imprinting or plugging of either native or non‐native species can be effective, but can result in increased erosion and weed proliferation prior to desirable cover of the intended species. The use of native species for rehabilitation can be preferable because non‐native species are often less suited to the local environment and can pose a threat to the integrity of adjacent ecosystems. Native multispecies sod could become a useful rehabilitation tool, but research is needed to determine which species to use and the appropriate number of species to include. Mixtures of 4–7 native species were grown for 7 months, and clipped dry biomass, species percent abundance, and total ground cover were assessed over time in order to determine the suitability of 20 native species for sod production. Despite differences between mixtures at some harvests, all mixtures established and produced similar biomass by the end of the study. Final percent cover varied widely among species; 16 of the 20 species increased significantly over the course of production. Differences in total ground cover between mixtures were explained by the growth of the particular species rather than any synergistic effect of species diversity.

Planted Grasslands and Native Sod Prairie: Equivalent Habitat for Grassland Birds?

Little is known about how avian relationships to tracts of native sod prairie compare with avian relation- ships to single and multiple species of cool- and warm-season grassland plantings. We compared grassland bird species richness and density in 5 grassland cover types (n = 97) in the tallgrass prairie region of eastern South Dakota and west- ern Minnesota, 2001-2004. Grassland bird species richness was significantly higher in native sod prairies than it was in all planted cover types except warm-season mixes. Grasslands dominated by exotic species did not support as many grassland bird species or have species densities as high as grasslands containing native species. Intermediate wheatgrass monotypes and cool-season mixes comprised of exotic species contained 40%-60% fewer grassland bird species than native sod prairie. Bobolink (Dolichonyx oryzivorus) density was 68% and 51% lower in intermediate wheatgrass mono- types and cool-season mixes, respectively, than it was in switchgrass monotypes. Clay-colored Sparrow (Spizella pallida) density was 75%-91% higher in native sod prairies than it was in any other cover type. Savannah Sparrow (Passerculus sandwichensis) density was 72% higher in native prairie than it was in grasslands dominated by exotic species. We rec- ommend incorporating a diversity of native plant species into grassland plantings for biomass fuels or wildlife, rather than using monotypes or exotic species, to provide habitat for grassland birds. Although replacing croplands with planted grasslands would benefit grassland bird populations, we caution that replacing existing native sod tracts with planted grasslands would be detrimental to populations of several grassland bird species.

A novel conjugate of low-molecular-weight heparin and Cu,Zn-superoxide dismutase: Study on its mechanism in preventing brain reperfusion injury after ischemia in gerbils

Low-molecular-weight heparin (LMWH) and Cu,Zn-superoxide dismutase (SOD) were extensively investigated on preventing brain reperfusion injury after ischemia (BRII) in the past few years and both exhibited some advantages as well as limits in practice. To explore whether chemical modification for LMWH and SOD can lead to improved bioactivity, in our present study, we examined the efficacy of LMWH conjugated SOD (LMWH − SOD) in the model of BRII gerbils. Ischemia/reperfusion was performed for 5 min by clamping the bilateral common carotid arteries of gerbils. LMWH − SOD, SOD and the mixture of LMWH and SOD (LMWH + SOD) were administered intravenously to corresponding animals just before ischemia. 24 h after reperfusion, serum malondialdehyde (MDA) content and SOD activity were measured, the expression of intercellular adhesion molecule-1 (ICAM-1) was examined by immunohistochemistry, and the brain sections were processed for Nissl staining and terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end-labeling. The results showed that LMWH − SOD significantly lowered MDA content ( P < 0.001, versus SOD and LMWH + SOD) and elevated SOD activity ( P < 0.05, versus SOD and LMWH + SOD) in the serum of BRII gerbils. Immunohistochemical results indicated ICAM-1 positive staining was lighter, pyramidal cells of hippocampal CA 1 region were more regular and the changes in cell edema were minor, and apoptosis of hippocampal cells was milder in LMWH − SOD treated animals than in SOD or LMWH + SOD treated animals, untreated BRII animals and sham-operated animals. The results suggest that the novel LMWH − SOD conjugate can inhibit upregulation of ICAM-1 and prevent neuronal cell apoptosis in BRII gerbils, and the LMWH − SOD conjugate has better anti-inflammatory and neuroprotective effects in BRII than native SOD and the mixture of LMWH and SOD.

SOIL CARBON DYNAMICS DURING A LONG-TERM INCUBATION STUDY INVOLVING 13C AND 14C MEASUREMENTS

Soil organic matter is the earth's largest terrestrial reservoir of carbon (C). Thus, it serves as a major control on atmospheric carbon dioxide (CO2) levels. To better understand these controls, decreases in soil organic C (SOC), soil microbial biomass (SMB) C, and the role of SMB as a source of mineralizable C were measured during a long-term incubation (853 days) without added substrate. The 2 soils used were a Weld loam (fine montmorillonitic, mesic, Aridic Paleustoll) from near Akron, Colorado, and a Duroc loam (fine silty, mixed mesic Pachic Haplustoll) from near Sidney, Nebraska. The Akron soil was uniformly cropped to small grain crop-fallow rotations until 1989 when wheat (Triticum aestivum L.) in conventional (stubble mulch) till-fallow, reduced till-fallow, and no-till fallow treatments were adopted. On additional rotation plots, continuous corn (Zea mays L.) or no-till corn, fallow, wheat, and no-till corn in a 4-year rotation were grown. The Sidney soil was broken from native sod in 1970 and planted to wheat-fallow with no-till, plow-tillage, and sod-plot treatments. Moist soil samples were collected and refrigerated until plant material removal by sieving and picking. The SOC and SMB-C decreased during incubation and rates of loss measured. The results from this study allow insights into contributions of SMB and changes in soil isotope C ratios not previously available. Soil microbial biomass C contributed an average of 31% of the evolved CO2-C across all treatments between day 10 and day 79 of incubation and an average of about 20% during the more extended times between later measurements thereafter. Until day 160, evolution of 13CO2 during incubation indicated that evolved C came from plant residues and was soil derived thereafter, including from the native grassland SOC. Where corn was grown, evolution of evolved C is hypothesized to have had a less negative 13CO2 isotope signature from days 630 to 720 of the incubation because of the delayed microbial breakdown of the cob materials. After 853 days of incubation and across all plots, the SOC remaining averaged 67% and was similar to the amount of observed hydrolysis residue C. Acid hydrolysis and 14C dating were also used to characterize the resistant SOC fraction and showed increased 14C age with hydrolysis but not with long-term incubation.

Immobilizing Cu,Zn-superoxide dismutase in hydrogels of carboxymethylcellulose improves its stability and wound healing properties

Hydrogels of carboxymethylcellulose (CMC) with 50 and 90% cross-linking degree (CMC50% and CMC90%, respectively) were prepared and loaded with bovine erythrocyte Cu,Zn-superoxide dismutase (SOD) to obtain two drug delivery systems: SOD-CMC50% and SOD-CMC90%. Resistance of native SOD to inactivation by H2O2 and the effect of applying SOD-CMC hydrogels to open wounds of rats' back skin were examined and compared to that of SOD trapped into CMC50% and CMC90% hydrogels. Also, the effect of CMC50% and SOD-CMC90% on human fibroblasts proliferation was evaluated at different times. It was found that SOD in the hydrogel was more resistant to H2O2 inactivation than the native enzyme and at the same time it reduced the time necessary for wound healing. Furthermore, the highest cell proliferation value was found for the CMC50% hydrogels, which had a three-dimensional structure suitable for gas and nutrient exchanges and improving cell life conditions.

(52) Evaluation of California Native Grasses for Revegetation Sod

The California Department of Transportation (Caltrans) has used hydroseeding, imprinting, and drill seeding methods to revegetate highway construction sites, with varying degrees of success. Ecological concerns, particularly in areas with high erosion potential, have led Caltrans to search for more-reliable plant establishment methods. One possibility is native sod, which should reduce erosion potential, and, the species would also be better suited to local environments, require less maintenance, and pose no invasive threat to adjacent ecosystems. In addition, the use of native sod may also reduce or prevent weed establishment. Our project aims to evaluate different native grass species mixes to determine the best species combinations for sod. We selected 21 species of native grasses in order to determine their suitability for sod production in six Californian ecoregions. Grasses were grown in six growth chambers that mimic the climate of the six ecoregions. Mixtures of varying species included either one rhizomatous species with three bunch grasses, one rhizomatous species and five bunch grasses, two rhizomatous species with three bunch grasses, or two rhizomatous species with five bunch grasses for each ecoregion. The mixtures were grown and tested for yield, species composition, and percentage of cover over time. At the end of the 6-month production time, a final harvest evaluated root depth and biomass as well as sod strength. Rhizomatous grasses, if planted with Bromus sp., were quickly overwhelmed. At the first harvest ground coverage was between 10% and 15% for all species mixes. Ground coverage increased over the production cycle, but maximum ground coverage remained less than 80% overall.

Structure−Activity Relationship of Cyclic Nitroxides as SOD Mimics and Scavengers of Nitrogen Dioxide and Carbonate Radicals

Synthetic nitroxide antioxidants attenuate oxidative damage in various experimental models. Their protective effect reportedly depends on ring size and ring substituents and is greater for nitroxides having lower oxidation potential. The present study focuses on the kinetics and mechanisms of the reactions of piperidine, pyrrolidine and oxazolidine nitroxides with HO2*/O2*-, *NO2 and CO3*- radicals, which are key intermediates in many inflammatory and degenerative diseases. It is demonstrated that nitroxides are the most efficient scavengers of *NO2 at physiological pH (k = (3-9) x 10(8) M(-1) s(-1)) and among the most effective metal-independent scavengers of CO3*- radicals (k = (2 - 6) x 10(8) M(-1) s(-1)). Their reactivity toward HO2*, though not toward *NO2 and CO3*-, depends on the nature of the ring side-chain and particularly on the ring-size. All nitroxide derivatives react slowly with O2*- and are relatively inefficient SOD mimics at physiological pH. Even piperidine nitroxides, having the highest SOD-like activity, demonstrate a catalytic activity of about 1000-fold lower than that of native SOD at pH 7.4. The present results do not indicate any correlation between the kinetics of HO2*/O2*-, *NO2 and CO3*- removal by nitroxides and their protective activity against biological oxidative stress and emphasize the importance of target-oriented nitroxides, i.e., interaction between the biological target and specific nitroxides.

Purification and some properties of superoxide dismutase from Deinococcus radiophilus, the UV-resistant bacterium.

The superoxide dismutase (SOD, EC 1.15.1.1) of Deinococcus radiophilus, a bacterium extraordinarily resistant to UV, ionizing radiations, and oxidative stress, was purified 1,920-fold with a 58% recovery yield from the cell-free extract of stationary cells by steps of ammonium sulfate fractionation and Superdex G-75 gel-filtration chromatography. A specific activity of the purified enzyme preparation was ca. 31,300 U mg(-1) protein. D. radiophilus SOD is Mn/FeSOD, judging by metal analysis and its insensitivity to cyanide and a partial sensitivity to H2O2. The molecular weights of the purified enzyme estimated by gel chromatography and polyacrylamide gel electrophoresis are 51.5+/-1 and 47.1+/-5 kDa, respectively. The SOD seems to be a homodimeric protein with a molecular mass of 26 +/- 0.5 kDa per monomer. The purified native SOD showed very acidic pI of ca. 3.8. The enzyme was stable at pH 5.0-11.0, but quite unstable below pH 5.0. SOD was thermostable up to 40 degrees C, but a linear reduction in activity above 50 degrees C. Inhibition of the purified SOD activity by beta-naphthoquinone-4-sulfonic acid, rho-diazobenzene sulfonic acid, and iodine suggests that lysine, histidine, and tyrosine residues are important for the enzyme activity. The N-terminal peptide sequence of D. radiophilus Mn/FeSOD (MAFELPQLPYAYDALEPHIDA(> D) is strikingly similar to those of D. radiodurans MnSOD and Aerobacter aerogenes FeSOD.