Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.3.3.1 (citrate synthase)
4,488 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effects of aging on myocardial antioxidant enzyme activity, lipid peroxidation, and other related biochemical properties were investigated in male Wistar-Furth rats at 4, 26, and 31 mo of age at rest and after an acute exercise bout. The results showed that resting heart cytosolic superoxide dismutase (CuZn SOD) activity was significantly decreased in the heart with aging (66 +/- 6.5 U/mg protein at 4 mo vs. 49 +/- 3.8 U/mg protein at 31 mo) and was elevated in all age groups after exercise. Mitochondrial Mn SOD activity was almost doubled in both 26- and 31-mo-old rats compared with that at 4 mo. Myocardial catalase and cytosolic glutathione peroxidase (GPX) activities were significantly decreased with age, whereas mitochondrial GPX was 29% higher (P less than 0.05) in 31- than 4-mo-old rats. Glutathione S-transferase activity in the heart also declined with age (P less than 0.05 at 31 mo). Malondialdehyde contents in both heart homogenate and mitochondria were significantly increased at old age. Activity of several enzymes related to myocardial energy production, e.g., citrate synthase, malate dehydrogenase, and lactate dehydrogenase, as well as myocardial protein content showed an age-related decline. These data indicate that myocardial antioxidant capacity is weakened during aging and that the compensatory increases of mitochondrial SOD and GPX may be an important mechanism in coping with free radical damage in senescent heart. Findings in the present investigation seem to support the free radical theory of aging.
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PMID:Myocardial aging: antioxidant enzyme systems and related biochemical properties. 187 97

We investigated whether X-irradiation could induce the enzyme superoxide dismutase (SOD) in intestinal muscle. Groups of rats received abdominal irradiation and the time course and dose response for SOD activity determined. Jejunal smooth muscle homogenates were analyzed for the activities of copper/zinc (CuZn) and manganese (Mn) SOD activity and for a mitochondrial marker enzyme, citrate synthase. A progressive rise in Mn SOD activity occurred at 20, 46, and 72 h after 1500 R. No significant changes in Cu-Zn SOD activity occurred at any time after 1500 R. At 20 h after 250 R of X-irradiation, Mn SOD activity increased but no further increase occurred at higher irradiation exposures. At the same time, CuZn SOD activity at 20 h after irradiation was greater than controls only at an exposure of 1000 R (p less than 0.05). Using Western blotting, we were able to clearly demonstrate an increase in immunoreactive Mn SOD protein in muscle samples 20 h after 1500 R. The rise in Mn SOD is not simply due to increase in mitochondrial numbers or increase in all mitochondrial enzyme activities because activity of the mitochondrial marker enzyme citrate synthase was decreased after X-irradiation. Transmission electron microscopic studies demonstrated damage to mitochondria after a dose of 3000 R. The data yield evidence that free radicals play a role in irradiation-induced intestinal smooth muscle injury.
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PMID:Irradiation increases superoxide dismutase in rat intestinal smooth muscle. 274 76

Local X-irradiation of mouse heart caused a large increase in manganese superoxide dismutase activity (MnSOD) in this organ but not in copper and zinc containing superoxide dismutase (Cu-Zn SOD) activity. MnSOD induction was both dose and time dependent. Another mitochondrial enzyme, citrate synthase, was not induced by X-irradiation. The amount of immunoreactive MnSOD also increased after X-irradiation, showing that the amount of MnSOD protein increased after X-irradiation. The response to X-irradiation was found to be biphasic--with one large peak and one smaller peak of manganese superoxide dismutase activity. The effect of various inhibitors of cellular activities on these two peaks of MnSOD activity was examined. Cycloheximide, a cytosolic protein synthesis inhibitor, abolished both peaks of MnSOD activity, while chloramphenicol, a mitochondrial protein synthesis inhibitor, has no effect on either peak. Actinomycin D, a RNA-synthesis inhibitor, lowered both peaks, but had more of an effect on the second peak than on the first. In vivo protein synthesis studies using [3H]arginine showed that an increase in new protein synthesis occurred during the time period of the second peak, but did not occur during the first peak. These results are consistent with the hypothesis that MnSOD induction occurs in two peaks with the first peak due to a preformed MnSOD protein or mRNA for MnSOD and the second peak due to an increase in new protein synthesis.
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PMID:Increase in manganese superoxide dismutase activity in the mouse heart after X-irradiation. 357 7

The chemical nature of the inactivation of citrate synthase by S-(4-bromo-2,3-dioxobutyl)-CoA, an active site-directed irreversible inhibitor, has been investigated. Active site-directed inactivation leads to derivatization of either Lys22 by epsilon-amino Schiff base formation or Glu363 by apparent alkylation of the gamma-carboxyl group, respectively. Lys22 is labeled in the tight (catalytic) form of the enzyme while Glu363 is labeled in the open (product release) form. Glu363 and Lys22 are both located at or near the entrance to an active site in the crystal structure of citrate synthase (Remington, S., Wiegand, G., and Huber, R. (1982) J. Mol. Biol. 158, 111-152). Glu363 is in the sequence of the protomer forming the active site while Lys22 is in the sequence of the other polypeptide in the homodimer. Labeling in this region appears to inactivate the enzyme by preventing access of substrates to the active site. A distinct and separate labeling process involves derivatization of Asn192 in the tight (catalytic) form and Ser198 and/or Ser199 in the open (product release) form at a locus far removed from the active site. Labeling at the second site may simply identify chemically reactive residues, or it may identify the binding site for long chain acyl-CoA, which has been identified as a possible allosteric negative effector of citrate synthase (Caggiano, A. V., and Powell, G. L. (1979) J. Biol. Chem. 254, 2800-2806). This second labeling process apparently inactivates the enzyme by interfering with catalytically essential conformational changes.
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PMID:S-(4-bromo-2,3-dioxobutyl)-CoA labels two distinct sites on citrate synthase. 372 59

Rats weighing 45-50 g were fed 3 diets for 8 wk: a balanced control diet (CD) consisting of 4% fat (polyunsaturated/saturated fatty acids [P/S] ratio 2.9/1) and two fat-rich diets: polyunsaturated (UD)--P/S 7.6/1 and saturated (SD) P/S 0.3/1. After 8 wk feeding on the respective diets, rats were subjected to swimming for 90 min at 30 degrees C daily, 5 d/wk for 8 wk. At the end of this period, the rats were killed and the lymphoid organs (LO--thymus, spleen, and mesenteric lymph nodes) and muscles (soleus and gastrocnemius) removed for the measurement of TBARs (Thiobarbituric Acid Reactant Substances) content and of the activities of antioxidant enzymes (CuZn- and Mn-Superoxide dismutase--SOD--, catalase, and glutathione peroxidase). To evaluate the changes in the sites of generation of reducing equivalents involved in the formation of free radicals, the activities of citrate synthase and glucose-6-phosphate dehydrogenase were measured. The exercise-training clearly modified the enzyme activities and TBARs content of the lymphoid organs and skeletal muscles, but this effect was dependent upon the diet given to the rats. However, fatty acid rich diets had presented a more pronounced effect on the studied aspects than did physical activity. Although one could expect a summatory effect of polyunsaturated fatty acid-rich diet and exercise-training, swimming increased the activities of CuZn- and Mn-SOD in almost all tissues from the elevated level promoted by fat-rich diets.
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PMID:Antioxidant enzyme activities in the lymphoid organs and muscles of rats fed fatty acids-rich diets subjected to prolonged physical exercise-training. 782 70

This study examined the effect of experimental hyper- and hypothyroidism on the superoxide dismutase, catalase and glutathione peroxidase activities of rat lymphoid organs (mesenteric lymph nodes, spleen and thymus) and muscles (soleus and gastrocnemius-white portion) for comparison. The capacity for the generation of reducing equivalents was also investigated: activities of glucose-6-phosphate dehydrogenase (pentose-phosphate pathway) and citrate synthase (Krebs cycle). Hyperthyroidism tended to enhance lipid peroxide content in all tissues. This effect may result from (1) a high capacity for the generation of reducing equivalents in cytosol and mitochondria and (2) a reduced activity of catalase in the lymphoid organs and of glutathione peroxidase in the muscles. The process of lipid peroxidation in these tissues caused by hyperthyroidism was probably slowed down by the augmentation of CuZn- and Mn-superoxide dismutase (Mn-SOD) activities observed under this condition. Hypothyroidism tended to diminish lipid peroxidation and did not affect citrate synthase and glucose-6-phosphate dehydrogenase activities in the lymphoid organs and muscles. Low levels of thyroid hormones tended to diminish Mn-SOD and glutathione peroxidase activities. These findings show that the thyroid hormones might be able to regulate the activities of CuZn- and Mn-SOD, and catalase and glutathione peroxidase in the lymphoid organs and skeletal muscles.
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PMID:Control of superoxide dismutase, catalase and glutathione peroxidase activities in rat lymphoid organs by thyroid hormones. 813 54

The alterations of superoxide dismutase iso-enzyme (Cu,Zn-SOD and Mn-SOD) activities, contents, and mRNA expressions with aging were studied in rat soleus muscle (SO) and extensor digitorum longus muscle (EDL). The activity and content of Cu,Zn-SOD in both muscles were significantly higher in old rats (24 months old) than in young rats (4 months old), whereas those of Mn-SOD showed no difference between young and old rats. After normalization to citrate synthase (CS) activity, however Mn-SOD/CS ratio in SO also showed the age-related increase. Moreover, the activities of other major antioxidant enzymes, glutathione peroxidase (GPX) and catalase (CAT), indicated age-related increases only in SO. As for the expressions of mRNAs for SOD iso-enzymes, that of Cu,Zn-SOD in either muscle showed no significant change with aging, unlike its activity and content, although that of Mn-SOD was decreased with aging only in EDL. Thus, aging appeared to raise the level of antioxidant enzyme system in rat skeletal muscle. However, the resistance of Cu,Zn-SOD and Mn-SOD to oxidative stress accompanied by aging was different, the former being obviously greater than the latter. Such changes also differed in muscle fiber type suggesting that fast-twitch fibers are more susceptible to age-related oxidative stress than slow-twitch fibers.
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PMID:Alterations of superoxide dismutase iso-enzyme activity, content, and mRNA expression with aging in rat skeletal muscle. 871 78

Amyotrophic lateral sclerosis is a fatal paralytic disorder of unknown cause. Recent evidence implicated the role of free radicals in the death of motor neurons in this disease. To investigate this hypothesis further, we measured the activity of the main free radical scavenging enzymes copper/zinc superoxide dismutase, manganese superoxide dismutase, catalase, and glutathione peroxidase in postmortem brain samples from 9 patients with sporadic amyotrophic lateral sclerosis and from 9 control subjects. We examined samples from the precentral gyrus of the cerebral cortex, a region affected in amyotrophic lateral sclerosis, and from the cerebellar cortex, a region not affected. The two groups did not differ in age or postmortem delay. In the precentral gyrus from amyotrophic lateral sclerosis samples, glutathione peroxidase activity as measured by spectrophotometric assay (13.8 +/- 2.6 nmol/min/mg protein [mean +/- standard error of mean]) was reduced significantly compared to the activity in the precentral gyrus from control samples (22.7 +/- 0.5 nmol/min/mg protein). In contrast, glutathione peroxidase activity was not significantly altered in the cerebellar cortex from amyotrophic lateral sclerosis patients compared to controls. Copper/zinc superoxide dismutase, manganese superoxide dismutase (corrected or not corrected for citrate synthase), and catalase were not significantly altered in the precentral gyrus or cerebellar cortex in the patient samples. This study indicated that glutathione peroxidase activity is reduced in a brain region affected in amyotrophic lateral sclerosis, thus suggesting that free radicals may be implicated in the pathogenesis of the disease.
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PMID:Brain superoxide dismutase, catalase, and glutathione peroxidase activities in amyotrophic lateral sclerosis. 896 46

The effects of endurance training on gene expression of superoxide dismutase (SOD) and glutathione peroxidase (GPX) were investigated in type 2a and 2b skeletal muscles, as well as heart and liver, in the rat. Female Sprague-Dawley rats (4 months old, 300-320 g) were randomly divided into a trained (T, n = 11) and a control (C, n = 10) group and were pair fed a diet consisting of 66% cornstarch and 34% basal diet that contained all essential nutrients. Training was conducted on a treadmill at 25 m x min(-1), 10% grade for 2 h per day, 5 days per week for 10 weeks, resulting in a 79% (p < 0.01) increase in citrate synthase activity in the deep portion of vastus lateralis muscle (DVL, type 2a). Cu-Zn SOD activity was 35% higher (p < 0.01) in DVL of T versus C rats, and Cu-Zn SOD mRNA abundance showed a 125% increase with training (p < 0.05). Cu-Zn SOD protein content was not altered in DVL, but increased significantly (p < 0.05) in the superficial portion of vastus lateralis (type 2b) with training. Trained rats showed a 66% higher (p < 0.05) Mn SOD protein content in DVL, but Mn SOD activity and mRNA abundance were not affected. Training also significantly increased GPX activity by 62% (p < 0.05), without changing its mRNA abundance, in the DVL. Heart and liver showed a 112 and 58% increase (p < 0.01) in Cu-Zn SOD mRNA abundance with training, respectively, but no other training adaptation was detected. These data indicate that endurance training can promote gene expression of muscle antioxidant enzymes in a fiber-specific manner. Training appears to upregulate Cu-Zn SOD mRNA abundance in a number of aerobic tissues, whereas Mn SOD and GPX induction observed in DVL may occur at the post-transcriptional levels.
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PMID:Endurance training alters antioxidant enzyme gene expression in rat skeletal muscle. 1032 36

Oxygen, while being an obligate fuel for aerobic life, has been shown to be toxic through its deleterious reactive species, which can cause oxidative stress and lead ultimately to cell and organism death. In marine organisms, reactive oxygen species (ROS), such as the superoxide anion and hydrogen peroxide, are generated within respiring cells and tissues and also by photochemical processes in sea water. Considering both the reduced metabolic rate of nektonic organisms thriving in the deep sea and the physico-chemical conditions of this dark, poorly oxygenated environment, the meso- and bathypelagic waters of the oceans might be considered as refuges against oxidative dangers. This hypothesis prompted us to investigate the activities of the three essential enzymes (superoxide dismutase, SOD; catalase, CAT; glutathione peroxidase, GPX) constitutive of the antioxidative arsenal of cells in the tissues of 16 species of meso- and bathypelagic fishes occurring between the surface and a depth of 1300 m. While enzymatic activities were detected in all tissues from all species, the levels of SOD and GPX decreased in parallel with the exponential reduction in the metabolic activity as estimated by citrate synthase activity. In contrast, CAT was affected neither by the metabolic activity nor by the depth of occurrence of the fishes. High levels of metabolic and antioxidative enzymes were detected in the light organs of bioluminescent species. The adjustment of the activity of SOD and GPX to the decreased metabolic activity associated with deep-sea living suggests that these antioxidative defense mechanisms are used primarily against metabolically produced ROS, whereas the maintenance of CAT activity throughout all depths could be indicative of another role. The possible reasons for the occurrence of such a reduced antioxidative arsenal in deep-sea species are discussed.
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PMID:Reduced enzymatic antioxidative defense in deep-sea fish. 1107 35


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