Superoxide Dismutase Type Research Articles

Role of manganese-containing superoxide dismutase in oxidative stress and virulence of Streptococcus pneumoniae.

Streptococcus pneumoniae was shown to contain two types of superoxide dismutase, MnSOD and FeSOD. Levels of MnSOD increased during growth in an aerobic environment. The sodA gene, encoding MnSOD, of virulent S. pneumoniae type 2 strain D39 was inactivated to give mutant D39HY1. Aerobically, D39HY1 had a lower growth rate than the wild type and exhibited susceptibility to the redox-active compound paraquat, but anaerobic growth of D39HY1 was identical to that of the wild type. Virulence studies showed that the median survival time of mice infected intranasally with D39HY1 was significantly longer than that of mice infected with the wild-type pneumococcus. In contrast to the wild type, D39HY1 did not multiply in lungs during the first 24 h but thereafter grew at the same rate as the wild type. Appearance in the bloodstream was also delayed, but growth in the blood was unimpaired by the sodA mutation. The pattern of inflammation in lungs infected with D39HY1 differed from that in wild-type-infected mice. After infection with D39HY1, neutrophils were densely packed around bronchioles, in contrast to the wild-type infection, where neutrophils were more diffusely localized.

Overexpression of copper/zinc superoxide dismutase does not prevent neonatal lethality in mutant mice that lack manganese superoxide dismutase

There are two types of intracellular superoxide dismutases: the mitochondrial manganese SOD (MnSOD) and the cytoplasmic copper/zinc SOD (CuZnSOD). Mutant mice that lack MnSOD die shortly after birth because of cardiomyopathy and mitochondrial injury. In order to verify if CuZnSOD could compensate for MnSOD deficiency, a new mutant mouse that overexpresses CuZnSOD but is deficient in MnSOD was generated by crossing MnSOD knockout mice with CuZnSOD transgenic mice. CuZnSOD activity was significantly increased in the blood, brain, liver, and heart of MnSOD knockout, CuZnSOD transgenic mice when compared with nontransgenic mice. However, overexpression of CuZnSOD did not prevent neonatal lethality in mice that lack MnSOD, nor did it prevent oxidative aconitase inactivation, nor did it rescue MnSOD-deficient astrocytes in culture. Based on our findings, which emphasize the strong enzymatic compartmentalization of CuZnSOD and MnSOD, therapeutic antioxidant strategies should consider the final intracellular localization of the antioxidant used, especially when those strategies are directed against mitochondrial diseases.

Cu/Zn- and Mn-superoxide dismutases are specifically up-regulated in neurons after focal brain injury.

In previous studies, we have demonstrated that damaged neurons within a boundary area around necrosis fall into delayed cell death due to the cytotoxic effect of microglial nitric oxide (NO), and are finally eliminated by activated microglia. In contrast, neurons in a narrow surrounding region nearby this boundary area remain alive even though they may encounter cytotoxic NO. To investigate the mechanism by which neurons tolerate this oxidative stress, we examined the in vitro and in vivo expression levels of superoxide dismutase (SOD) under pathological conditions. Results from our in situ hybridization and immunohistochemical studies showed up-regulation of Cu/Zn-SOD only in neurons outside the boundary area, whereas up-regulation of Mn-SOD was detected in both neurons and glial cells in the same region. In vitro experiments using rat PC12 pheochromocytoma and C6 glioma cell lines showed that induction of both Cu/Zn- and Mn-SOD mRNA could only be detected in PC12 cells after treatment with NO donors, while a slight induction of Mn-SOD mRNA alone could be seen in C6 glioma cells. The mechanism of resistance toward oxidative stress therefore appears to be quite different between neuronal and glial cells. It is assumed that these two types of SOD might play a critical role in protecting neurons from NO cytotoxicity in vivo, and the inability of SOD induction in damaged neurons seems to cause their selective elimination after focal brain injury.

Capillary gel electrophoretic separation of superoxide dismutases in leaf extracts of Triticum aestivum L.

Capillary gel electrophoretic (CGE) separation of metal superoxide dismutase (SOD; EC 1.15.1.1) types is described. A mixture of standard SOD types was fully denatured into SDS–SOD complexes in the presence of excess sodium dodecylsulphate (SDS). The SDS–SOD complexes were separated using an uncoated fused silica capillary filled with a polymer running buffer and detected spectrophotometrically at 200 nm. Three types of SOD were separated, namely, Cu/ZnSOD (32 kDa), FeSOD (38 kDa) and MnSOD (40 kDa). Calibration curves were linear in the concentration range of 0.1–5.0 mg/mL with a detection limit in the order of 0.05 mg/mL. The reproducibility of the migration time was high with a relative standard deviation of less than 1.50%. The proposed method was demonstrated to be applicable to the separation of SOD types in leaf extracts of wheat. Copyright © 2000 John Wiley & Sons, Ltd.

Superoxide dismutase expression in the human corpus luteum during the menstrual cycle and in early pregnancy

To investigate the possible role of the superoxide radical and its scavenging system in the human corpus luteum, superoxide dismutase (SOD) values and lipid peroxide concentrations were analysed in the corpora lutea during the menstrual cycle and in early pregnancy. Copper-zinc SOD (Cu,Zn-SOD) activities increased from the early to mid-luteal phase, and gradually decreased thereafter and were the lowest in the regression phase. In pregnant corpus luteum, Cu,Zn-SOD activities were significantly higher than those in the mid-luteal phase. In contrast, manganese SOD (Mn-SOD) activities were low in the mid-luteal phase and increased toward the regression phase. Changes in mRNA expression of both types of SOD were similar to changes in their activities. Lipid peroxide concentrations were the highest in the regression phase whereas they were remarkably low in pregnant corpus luteum. The effects of human chorionic gonadotrophin (HCG) on luteal SOD were studied in vitro. HCG significantly increased Cu,Zn-SOD expression in mid-luteal phase corpora lutea, but not in late luteal phase corpora lutea. In conclusion, the present study suggests that the superoxide radical and its scavenging system, especially Cu,Zn-SOD, play important roles in the regulation of human luteal function. The stimulation of luteal Cu, Zn-SOD expression by HCG may be important in maintaining luteal cell integrity when pregnancy occurs.

Pharmacological modifications of endogenous antioxidant enzymes with special reference to the effects of deprenyl: a possible antioxidant strategy

Limited information is available on the upregulation of endogenous antioxidant enzymes by means of administering various pharmaceuticals and/or chemicals. It has been reported that ursodeoxycholic acid (UDCA), a bile acid originally identified from black bear bile (a Chinese medicine, Yutan) increased glutathione S-transferase (GST) activities in mouse livers, resulting in a decrease in systemic lethal toxicity of orally challenged 1-2-dichloro-4-nitrobenzene (DCNB). Also, ursolic acid found in herbal medicines (e.g. leaves of loquat) was reported to increase catalase (CAT) activities in mouse liver. Interestingly, the chemical structures of these two compounds are surprisingly similar to each other, despite the difference in their original sources. These results suggest that in the future, more and more compounds will be found to have effects on increasing endogenous antioxidant enzyme activities. Deprenyl is a monoamine oxidase B inhibitor but also possesses many other different pharmacological activities. Among these various pharmacological effects of deprenyl, a possible causal relationship between two effects of deprenyl, namely the prolongation of the survival of animals and upregulation of antioxidant enzymes in selective brain regions, has been postulated by the authors. In at least four different animal species (rats, mice, hamsters and dogs), a significant prolongation of survival by chronic administration of the drug has been reported by different groups including that of the authors. This group has reported that repeated administration of the drug for 2–3 weeks can significantly increase activities of both types of superoxide dismutase (SODs) (Cu, Zn-, and Mn-SODs) as well as of CAT selectively in brain dopaminergic regions. Both effects are dose dependent but excessive dosages become less effective and even cause an adverse effect (i.e. a decrease in enzyme activities and shortening of life span). The parallelism of the dose-effect relationship between the two phenomena suggests that modification of SOD and CAT levels is one possible mechanism for deprenyl’s ability to prolong the life span of animals.

Characterization of superoxide dismutase activity in Chironomus riparius Mg. (Diptera, Chironomidae) larvae — a potential biomarker

The activities of superoxide dismutase (SOD) isoenzymes were measured in fourth instar larvae of Chironomus riparius Mg. Three types of superoxide dismutase were identified: Cu,Zn-SOD in hemolymph and postmitochondrial fraction; Mn-SOD in mitochondrial fraction and presumably Fe-SOD in postmitochondrial fraction. The latter could have an endosymbiotic or a parasitic origin. Extracellular and cytosolic SOD activities, especially Cu,Zn-SOD, tended to increase in the last phase of larval development, independently of protein or hemoglobin contents. This supposes that SOD activity in Ch. riparius larvae is probably activated at the end of fourth instar stage. Cu,Zn-SOD and Mn-SOD activities showed a significant increase under severe hypoxia and slight hyperoxia. Oxygen radical scavengers such as SOD may play a role in the increased tolerance of Ch. riparius to oxidative stress. These results suggest that the specific induction of some SOD isoenzymes could be used as a biomarker of environmental disturbance such as oxidative stress initiated by xenobiotics.

Duplicate genes for Fe-containing superoxide dismutase in Streptomyces coelicolor A3(2).

Streptomyces coelicolor Müller contains two types of superoxide dismutase (SOD) containing Ni (encoded by sodN) or Fe (encoded by sodF). Unlike a single species of Fe-containing SOD in Müller strain, multiple forms of FeSODs were detected in S. coelicolor A3(2) strain by activity staining and Western blot analysis. Genomic Southern hybridization suggested the presence of at least two copies of the sodF-like gene in A3(2). Two different genes for FeSOD (sodF1 and sodF2) were isolated from the phage library of A3(2) genome. The nucleotide sequence of the sodF1 coding region was identical with the unique sodF gene from Müller while that of sodF2 shared 88% identity. The gene products of sodF1 and sodF2 were identified by activity staining and immunoblot analysis. Expression from the sodF1 gene was repressed by nickel as sensitively as Müller sodF, suggesting the presence of Ni-responsive regulatory site within the region shared by the two genes. Among 12 other Streptomyces species examined, only S. fradiae contained two FeSOD-like polypeptides. We postulate that the additional copy of the sodF gene (sodF2) was provided by the horizontal transfer from remotely related bacteria.

Lack of involvement of neuronal nitric oxide synthase in the pathogenesis of a transgenic mouse model of familial amyotrophic lateral sclerosis

A subset of familial cases of amyotrophic lateral sclerosis are linked to missense mutations in copper/zinc superoxide dismutase type 1. Patients with missense mutations in copper/zinc superoxide dismutase type 1 develop a paralytic disease indistinguishable from sporadic amyotrophic lateral sclerosis through an unknown toxic gain of function. Nitric oxide reacts with the superoxide anion to form the strong oxidant, peroxynitrite, which participates in neuronal injury in a variety of model systems. Peroxynitrite is an alternate substrate for copper/zinc superoxide dismutase type 1, causing catalytic nitration of tyrosine residues in other proteins. Mutations in copper/zinc superoxide dismutase type 1 may disrupt the active site of the enzyme and permit greater access of peroxynitrite to copper, leading to increased nitration by peroxynitrite of critical cellular targets. To investigate whether neuronal-derived nitric oxide plays a role in the pathogenesis of familial amyotrophic lateral sclerosis, we examined the effects of three different nitric oxide synthase inhibitors: a non-selective nitric oxide synthase inhibitor, nitro- l-arginine methyl ester; a relatively selective inhibitor of neuronal nitric oxide synthase, 7-nitroindazole; and a novel highly selective neuronal nitric oxide synthase inhibitor, AR-R 17,477, in transgenic mice expressing a familial amyotrophic lateral sclerosis-linked mutant human copper/zinc superoxide dismutase type 1 (Gly→Ala at position 93; G93A) containing a high transgene copy number and a low transgene copy number. AR-R 17,477, but not nitro- l-arginine methyl ester or 7-nitroindazole, significantly prolonged survival in both the high and low transgene transgenic mice. To determine whether neuronal nitric oxide synthase is involved in the pathogenesis resulting from the familial amyotrophic lateral sclerosis copper/zinc superoxide dismutase type 1 mutation, we produced mice with the copper/zinc superoxide dismutase type 1 mutation which lack the neuronal nitric oxide synthase gene. The transgenic mice expressing a familial amyotrophic lateral sclerosis-linked mutant human copper/zinc superoxide dismutase type 1 on neuronal nitric oxide synthase null background do not live significantly longer than transgenic mice expressing a familial amyotrophic lateral sclerosis-linked mutant human copper/zinc superoxide dismutase type 1. Western blot analysis indicates the presence of two neuronal nitric oxide synthase-like immunoreactive bands in spinal cord homogenates of the neuronal nitric oxide synthase null mice, and residual neuronal nitric oxide synthase catalytic activity (>7%) is detected in the spinal cord of the transgenic mice expressing a familial amyotrophic lateral sclerosis-linked mutant human copper/zinc superoxide dismutase type 1 on neuronal nitric oxide synthase null background. This amount of residual activity probably does not account for lack of protection afforded by the disrupted neuronal nitric oxide synthase gene in the familial amyotrophic lateral sclerosis-linked mutant human copper/zinc superoxide dismutase type 1 mice. Immunological nitric oxide synthase is not detected in the copper/zinc superoxide dismutase type 1 mutant mice at several different ages, thus excluding immunological nitric oxide synthase as a contributor to the pathogenesis of familial amyotrophic lateral sclerosis. Levels of neuronal nitric oxide synthase as well as Ca 2+-dependent nitric oxide synthase catalytic activity in the copper/zinc superoxide dismutase type 1 mutant mice do not differ from wild type mice. Endothelial nitric oxide synthase levels may be decreased in the copper/zinc superoxide dismutase type 1 mutant mice. Together, these results do not support a significant role for neuronal-derived nitric oxide in the pathogenesis of familial amyotrophic lateral sclerosis transgenic mice.

Different Types of ROS-Scavenging Enzymes Are Expressed during Cutaneous Wound Repair

Injury to the skin initiates a series of events including inflammation, new tissue formation, and matrix remodeling. During the early inflammatory phase, polymorphonuclear leukocytes and macrophages infiltrate the wounded tissue. Once activated, they produce large amounts of reactive oxygen species (ROS) as part of their defense mechanism. Although this process is beneficial, increased levels of ROS can inhibit cell migration and proliferation and can even cause severe tissue damage. Therefore, cells must develop strategies for the detoxification of these molecules. To gain insight into the mechanisms which underlie this process, we analyzed the temporal and spatial expression pattern of various ROS-scavenging enzymes during the healing process of full-thickness excisional wounds in mice. Here we demonstrate a strong mRNA expression of two types of superoxide dismutase (SOD), as well as of catalase, and the selenoenzymes glutathione peroxidase (SeGPx) and phospholipid hydroperoxide glutathione peroxidase in normal and wounded skin. Most importantly, mRNA levels of the SODs and of SeGPx increased strongly after skin injury.In situhybridization and immunofluorescence studies revealed the presence of these transcripts at multiple places in the wound, whereby particularly high expression levels were detected in the hyperproliferative epithelium and the hair follicles at the wound edge. These data suggest an important role of ROS-scavenging enzymes in the detoxification of ROS during cutaneous wound repair.

Purification and identification of the type of superoxide dismutase fromGlœocapsa sp.

Superoxide dismutase purified from the photoautotrophic cyanobacteriumGlœocapsa sp. has a molar mass of 38 kDa, as estimated by gel filtration. Inhibition pattern indicated limited resistance to H2O2 under conditions which entirely inhibited FeSOD. The enzyme is insensitive to cyanide and is inhibited by azide. This suggested the presence of a hybrid of two isozymes, FeSOD and a minor constituent of MnSOD. Amino acid composition of the purified SOD showed structural homology to FeSOD and MnSOD apoenzymes.

Scavenging of superoxide and hydrogen peroxide in blue‐green algae (cyanobacteria)

Blue‐green algae (cyanobacteria) have evolved as the most primitive, oxygenic, plant‐type photosynthetic organisms. Within a single prokaryotic cell, they have uniquely accommodated both oxygenic photosynthesis and aerobic respiration, which are known to produce superoxide and hydrogen peroxide as inevitable byproducts. Two types of superoxide dismutase have been characterized in both N2‐fixing and non‐N2‐fixing cyanobacteria, namely cytosolic iron‐containing superoxide dismutase and thylakoid‐bound manganese‐containing superoxide dismutase. No qualitative differences between various cell types (vegetative cells, heterocysts) were found. In contrast to chloroplasts, most of the cyanobacterial species show catalatic activity. From two species the corresponding enzymes have been characterized as typical prokaryotic (bifunctional) catalase‐peroxidases with homologies to cytochrome c peroxidases and ascorbate peroxidases. In addition to catalatic activity, some strains exhibit ascorbate peroxidase activity, but to date there are no reports detailing purification and characterization.Cyanobacteria were found to contain low intracellular ascorbate concentrations (30‐100 µM) and 2‐5 mM glutathione. Both monodehydroascorbate and glutathione reductase activities were detected in most species examined, whereas dehydroascorbate reductase activity was absent. The question as to whether a glutathione‐ascorbate cycle exists in cyanobacteria cannot be answered at present.

Cyclin-dependent kinase-5 is associated with lipofuscin in motor neurones in amyotrophic lateral sclerosis

We have studied the distribution of cyclin dependent kinase-5 (cdk-5) within spinal cord in sporadic and two superoxide dismutase type 1 (SOD1) familial cases of amyotrophic lateral sclerosis (ALS). Although most neurofilament accumulations in ALS motor neurones did not appear to contain high levels of cdk-5, intense cdk-5 immunoreactivity was observed in perikarya of degenerating neurones in many ALS cases. Here, cdk-5 co-localised with lipofuscin. Co-localisation of cdk-5 with lipofuscin was also observed in some aged non-affected controls although this labelling was less intense than the ALS cases. The biogenesis of lipofuscin is believed to be linked to oxidative stress and oxidative stress and free radical damage have been suggested to be part of the pathogenic process of ALS, possibly involving apoptotic mechanisms. cdk-5 has recently been associated with apoptosis. These observations suggest a role for cdk-5 in the pathogenesis of ALS.

Copper–zinc superoxide dismutase is a constituent enzyme of the matrix of peroxisomes in the cotyledons of oilseed plants

The number and type of isoforms of superoxide dismutase (SOD) and their activities were compared in mitochondria and peroxisomes isolated from cotyledons of three different oilseed seedlings. Mitochondrial and peroxisomal isoforms of SOD could be distinguished in nondenaturing polyacrylamide gels by their differential sensitivities to KCN and/or H2 O2 . The type of SOD was not the same for each organelle in each of the three oilseed species. For example, a single Mn-SOD was found in cotton and cucumber mitochondria, whereas four CuZn-SODs were present in mitochondria from sunflower. At least one CuZn-SOD isoform was found in the peroxisomes of all three species. Cucumber peroxisomes contained both a CuZn-SOD and a Mn-SOD, cotton peroxisomes contained a single CuZn-SOD, whilst four separate CuZn-SODs, but no Mn-SOD were found in sunflower peroxisomes. Using antibodies against CuZn-SOD from watermelon peroxisomes or from chloroplasts of Equisetum, a single polypeptide of c. 16·5 kDa was detected on immunoblots of peroxisomal fractions from the three species. Post-embedment, electron-microscopic double immunogold-labelling showed that CuZn-SOD, with malate synthase used as marker enzyme of peroxisomes, was localized in the matrix of these organelles of all three species. These results suggest that CuZn-SOD is a characteristic matrix enzyme of peroxisomes in oilseed cotyledons.

Studies of the Cellular Distribution of Superoxide Disrnutases in Adult and Fetal Rat Tissues

Activities of three types of superoxide dismutase in tissue fractions were significantly lower in fetal and adult brain and fetal limb preparations than in fetal and adult heart preparations. An exception was the cyto-plasmic fraction of adult brain that had levels of Cu, Zn-superoxide dismutase activity comparable to those in cytoplasmic fractions of heart. In addition, Mn superoxide dismutase activity appeared to be very low in all fetal mitochondrial matrix fractions and cytoplasmic fractions as well as in adult brain. Finally, the results of these studies emphasize the importance of two antioxidant defense systems in the tissues studied, one associated with the mitochondrial electron transport system and the other, the cytosolic Cu, Zn enzyme.

Transcriptional and post-transcriptional regulation by nickel of sodN gene encoding nickel-containing superoxide dismutase from Streptomyces coelicolor Müller.

A novel type of superoxide dismutase containing nickel as a cofactor (NiSOD) has been discovered in several Streptomyces spp. The gene for NiSOD (sodN) was cloned from S. coelicolor Müller using degenerate oligonucleotide probes designed from the N-terminal peptide sequence of the purified enzyme. It encodes a polypeptide of 131 amino acids (14703 Da), without any apparent sequence similarity to other known proteins. The N-terminus of the purified NiSOD was located 14 amino acids downstream from the initiation codon of the deduced open reading frame (ORF), indicating the involvement of protein processing. The molecular mass of the processed polypeptide was predicted to be 13201 Da, in close agreement with that of the purified NiSOD (13.4 kDa). The transcription start site of the sodN gene was determined by S1 mapping and primer extension analysis. Ni2+ regulates the synthesis of NiSOD polypeptide. S1 mapping of both 5' and 3' ends of sodN mRNA revealed that Ni2+ increased the level of monocistronic sodN mRNA by more than ninefold without changing its half-life, thus demonstrating that Ni2+ regulates transcription. Both precursor and processed NiSOD polypeptides with little SOD activity were produced from the cloned sodN gene in S. lividans in the absence of sufficient Ni2+; however, on addition of Ni2+, active NiSOD consisting of only processed polypeptide was formed. Expression of the full-length sodN gene in E. coli produced NiSOD polypeptide without any SOD activity even in the presence of Ni2+. However, deletion of nucleotides encoding the N-terminal 14 amino acids from the sodN gene allowed the production of active NiSOD in E. coli, indicating that N-terminal processing is required to produce active NiSOD. These results reveal the unique role of nickel as a multifaceted regulator in S. coelicolor controlling sodN transcription and protein processing, as well as acting as a catalytic cofactor.

Contribution to subcellular localization of superoxide dismutase isoforms of spruce needles and oak leaves

Summary The aim of this work was to determine the number and the types of superoxide dismutase (EC 1.15.1.1) from spruce needles and oak leaves as well as to examine their localization at the subcellular level. The obtained results show that spruce needles contain one mitochondrial, matricial Mn-SOD form and four Cu,Zn-SOD isozymes. One of these forms, SOD 4, was located in the chloroplast where it seemed to be bound to the thylakoids. Concerning oak leaves, five SOD forms were detected, all belonging to the Cu,Zn-SOD type. SOD 1 was found in the mitochondria whereas SOD 5 was a chloroplastic, stromatal form.

Effect of high temperature treatment of Vicia faba roots on the oxidative stress enzymes in leaves.

The following types of superoxide dismutase (SOD) have been found in the leaves of Vicia faba: one isoenzyme of Mn-SOD and four isoenzymes of Cu/Zn-SOD. The treatments of roots with boiling water caused an increase of SOD activity in the leaves. The highest increase was measured after 5 s of the treatment. It was accompanied by a significant increase in catalase activity. Analysis of cell fractions' revealed an increase of SOD activity in the plastids and mitochondria isolated from the leaves of those plants whose roots were heat-treated. However, there was no distinct change of SOD activity in the cytosolic fraction. The possibility of an electric wave intervention inducing oxidative stress in the leaves is discussed.

Differential expression of superoxide dismutases containing Ni and Fe/Zn in Streptomyces coelicolor.

Streptomyces coelicolor contains two distinct superoxide dismutase (SOD) activities detected on native PAGE. The level of each changed differently depending on growth media and scarcely responded to paraquat, a superoxide-generating agent. The total SOD activity doubled in late exponential phase compared with that in mid-exponential phase and less than double upon treatment with plumbagin, another superoxide-generating agent. The two SODs from S. coelicolor ATCC 10147 (Müller) strain were purified to near homogeneity. SOD1, a tetramer of 13.4-kDa subunits, was found to be a novel type of SOD containing 0.74 mol nickel/mol subunit as determined by atomic absorption spectroscopy. SOD2, a tetramer of 22.2-kDa subunits, was found to contain 0.36 mol iron and 0.26 mol zinc/mol subunit. The N-terminal amino acid sequences of both SODs were determined. SOD2 is similar to manganese-containing superoxide dismutases (MnSODs) and iron-containing superoxide dismutases (FeSODs) from other organisms, whereas SOD1 is less similar to known SODs but still contains a few conserved amino acids. The effects of metals and chelating agents on the expression of these two SODs were examined. The presence of nickel at micromolar concentrations in growth media induced the expression of SOD1 (nickel-containing superoxide dismutase; NiSOD), whereas the expression of SOD2 (iron/zinc-containing superoxide dismutase; FeZnSOD) was repressed. The changes in SOD activities were positively correlated with the amount of each enzyme as determined by immunoblotting, suggesting that metals do not modulate the activity per se but the amount of each protein.

Effects of lecithinized superoxide dismutase on rat spinal cord injury.

Although superoxide dismutase (SOD) has been reported to promote functional recovery in ischemic spinal cord injury, it presents many difficulties in practical use primarily due to its short half-life in vivo and low tissue affinity. In this study, we investigated the effects of a new type of SOD, a lecithinized superoxide dismutase (PC-SOD), on motor disturbances, spinal cord edema, levels of myeloperoxidase (MPO), and spinal cord blood flow (SCBF) after spinal cord injury (SCI) in rats. PC-SOD is reported to show a delayed plasma disappearance in vivo in rats and has a higher affinity for vascular endothelium cells, neutrophils, and other cells than unmodified SOD. PC-SOD (4000 units/kg), unmodified SOD (4000 units/kg), or vehicle was injected intravenously 30 min after SCI. Four hours after SCI, SOD activities in spinal cord tissue and plasma were significantly higher in the PC-SOD group than in the unmodified SOD group. In the PC-SOD-treated rats, motor function was significantly better than in the other 2 groups of rats. PC-SOD significantly suppressed MPO activity, an indicator of neutrophils infiltration, in the spinal cord, at 4, 8, and 24 h after SCI, and spinal cord edema at 24 h after SCI. Moreover, the decrease of SCBF after SCI was less marked in the PC-SOD group. The present results suggest that lecithinization can improve the drug delivery of SOD to the spinal cord and PC-SOD may be an alternative pharmacological treatment for SCI.