Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.3.3.1 (citrate synthase)
 4,488 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. The effect of administration of fish oil by gavage on key enzyme activities of glucose metabolism of the thymus, spleen, and mesenteric lymph nodes was investigated. 2. The activities of hexokinase, glucose-6-phosphate dehydrogenase, and citrate synthase in the lymphoid organs were markedly raised due to a daily administration of fish oil by gavage (0.4% of body weight). 3. These findings indicate that the therapeutic utilization of fish oil does affect the metabolism of the lymphoid organs, and possibly immune function; however, the mechanism involved remains to be investigated.
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PMID:Administration of fish oil by gavage increases the activities of hexokinase, glucose-6-phosphate dehydrogenase, and citrate synthase in rat lymphoid organs. 890 80

We measured enzyme activities along a heterothermic tissue, the visceral retia mirabilia of the bluefin tuna, to test current theories of enzyme temperature adaptation. The heterothermic tissue model is ideal for the study of fundamental temperature adaptation because it eliminates confounding effects of whole animal acclimation. Enzymes were measured at six positions along the rete at four temperatures (15, 20, 25, and 30 degrees C). Five enzymes (aspartate aminotransferase, citrate synthase, glucose-6-phosphate dehydrogenase, glutamate dehydrogenase, and pyruvate kinase) exhibited a significant positive compensatory effect, with activity at the cold end of the rete 1.2-3.1 times higher than at the warm end. Two enzymes (alanine aminotransferase and lactate dehydrogenase) exhibited no significant compensation. On the basis of activation energies of enzymes along the rete, differences in activity were due to differences in enzyme concentration and not isozymes or enzyme modification. Analysis of the compensatory responses of the enzymes in light of their thermal sensitivities leads us to conclude that the pentose phosphate shunt is especially enhanced at the cold end of the rete.
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PMID:Enzyme adaptation along a heterothermic tissue: the visceral retia mirabilia of the bluefin tuna. 922 97

The effect of gonadectomy on lymphocyte proliferation and macrophage function (hydrogen peroxide production and phagocytosis capacity) of male and female rats was examined and the results correlated with the activities of hexokinase, glucose-6-phosphate dehydrogenase, citrate synthase and phosphate-dependent glutaminase. Also, the reversion of the changes by the treatment with oestrogen or progesterone or a combination of both was addressed. Taken as a whole, ovariectomy reduced hydrogen peroxide production and phagocytosis capacity by macrophages and also lymphocyte proliferation. Castration of male rats reduced the proliferation of lymphocytes and raised macrophage phagocytosis capacity. The effects on macrophage function were correlated with changes in glucose metabolism, particularly, in the activity of glucose-6-phosphate dehydrogenase.
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PMID:Gonadectomy impairs lymphocyte proliferation and macrophage function in male and female rats. Correlation with key enzyme activities of glucose and glutamine metabolism. 941 77

A study was undertaken to estimate the activities of the key enzymes of glycolysis, the pentose phosphate pathway and the tricarboxylic acid (TCA) cycle in purified rat spermatocytes and spermatids, which have been shown to die in glucose-containing medium and require lactate/pyruvate for maintaining normal ATP concentrations. The aim was to elucidate the changes in the glycolytic and oxidative potential of germ cells undergoing meiosis. Pachytene spermatocytes and round spermatids from adult rat testis were purified to approximately 90% purity by trypsin digestion followed by a combination of centrifugal elutriation and Percoll density gradient centrifugation. After the purity and viability of these cells had been established, their contents of hexokinase, phosphofructokinase, lactate dehydrogenase (LDH) and LDH-X of glycolysis, glucose 6-phosphate dehydrogenase of the pentose phosphate pathway and citrate synthase, aconitase, malate dehydrogenase and 2-oxoglutarate dehydrogenase of the TCA cycle were estimated. These enzymes were also estimated in epididymal spermatozoa for comparison with the testicular germ cells. The results indicate greater activity of glycolytic and pentose phosphate pathway enzymes in spermatocytes than in spermatids, which exhibited greater activity of TCA cycle enzymes than the former. The difference in activity was statistically significant for most of the enzymes studied. In contrast, spermatozoa exhibited markedly greater activity of glycolytic enzymes and significantly lower activity of pentose phosphate pathway and TCA cycle enzymes than did the testicular germ cells. We conclude that the unusual dependence of spermatids exclusively on lactate may be due to their lower glycolytic potential, whereas spermatocytes with comparatively greater glycolytic activity have an intermediate dependence on lactate and are therefore able to utilise lactate, pyruvate, or both, while retaining a better ability to utilise glucose. Spermatozoa with the greatest glycolytic potential and the lowest TCA cycle activity appear to be 'programmed' to utilise exclusively glucose/fructose for energy.
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PMID:Changes in carbohydrate metabolism of testicular germ cells during meiosis in the rat. 953 8

Thiobarbituric acid reactant substances (TBARs) content, and the activities of glucose-6-phosphate dehydrogenase (G6PDh), citrate synthase (CS), Cu/Zn- and Mn-superoxide dismutase (SOD), catalase, and glutathione peroxidase (GPX) were measured in the lymphoid organs (thymus, spleen, and mesenteric lymph nodes (MLN)) and skeletal muscles (gastrocnemius and soleus) of adrenodemedullated (ADM) rats. The results were compared with those obtained for sham-operated rats. TBARs content was reduced by adrenodemedullation in the lymphoid organs (MLN) (28%), thymus (40%) and spleen (42%)) and gastrocnemius muscle (67%). G6PDh activity was enhanced in the MLN (69%) and reduced in the spleen (28%) and soleus muscle (75%). CS activity was reduced in all tissues (MLN (75%), spleen (71%), gastrocnemius (61%) and soleus (43%)), except in the thymus which displayed an increment of 56%. Cu/Zn-SOD activity was increased in the MLN (126%), thymus (223%), spleen (80%) and gastrocnemius muscle (360%) and was reduced in the soleus muscle (31%). Mn-SOD activity was decreased in the MLN (67%) and spleen (26%) and increased in the thymus (142%), whereas catalase activity was reduced in the MLN (76%), thymus (54%) and soleus muscle (47%). It is particularly noteworthy that in ADM rats the activity of glutathione peroxidase was not detectable by the method used. These data are consistent with the possibility that epinephrine might play a role in the oxidative stress of the lymphoid organs. Whether this fact represents an important mechanism for the establishment of impaired immune function during stress remains to be elucidated.
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PMID:Changes in the TBARs content and superoxide dismutase, catalase and glutathione peroxidase activities in the lymphoid organs and skeletal muscles of adrenodemedullated rats. 969 30

The elevated rate of oxygen consumption and high amount of polyunsaturated fatty acids make the central nervous system vulnerable to oxidative stress. The effect of Walker-256 tumor growth on oxi-reduction indexes in the hypothalamus (HT), cortex (CT), hippocampus (HC) and cerebellum (CB) of male Wistar rats was investigated. The presence of the tumor caused an increase in thiobarbituric acid reactant substances (TBARs) in the HT, CB and HC. Due to tumor growth, the activity of glucose-6-phosphate dehydrogenase increased in the HT and CB, whereas citrate synthase activity was reduced in the HT, CT and CB. Therefore, the potential for generation of reducing power is increased in the cytosol and decreased in the mitochondria of various brain regions of Walker-256 tumor-bearing rats. These changes occurred concomitantly with an unbalance in the brain enzymatic antioxidant system. The tumor decreased the activities of catalase in the HT and CB and of glutathione peroxidase in the HT, CB and HC, and raised the CuZn-superoxide dismutase activity in the HT, CB and HC. These combined findings indicate that Walker-256 tumor growth causes oxidative stress in the brain.
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PMID:Walker-256 tumor growth causes oxidative stress in rat brain. 1129 28

The effects of iron deficiency and iron resupply on the metabolism of leaf organic acids have been investigated in hydroponically grown sugar beet. Organic acid concentrations and activities in leaf extracts of several enzymes related to organic acid metabolism were measured. Enzymes assayed included phosphoenol pyruvate carboxylase (PEPC; EC 4.1.1.31), different Krebs cycle enzymes: malate dehydrogenase (MDH; EC 1.1.1.37), aconitase (EC 4.2.1.3), fumarase (EC 4.2.1.2), citrate synthase (CS; EC 4.1.3.7) and isocitrate dehydrogenase (ICDH; EC 1.1.1.42), glucose-6-phosphate dehydrogenase (G6PDH; EC 1.1.1.49) and two enzymes related to anaerobic metabolism (lactate dehydrogenase [LDH]; EC 1.1.1.27, and pyruvate decarboxylase [PDC]; EC 4.1.1.1). Iron concentration in leaves was severely decreased by iron deficiency. Iron resupply caused an increase in iron concentrations, reaching levels similar to the controls in 96 h. Iron deficiency induced a 2.3-fold (from 16 to 37 mmol m-2) increase in leaf total organic acid concentration. Organic anion concentrations were still 4-fold higher than the controls 24 h after resupply and decreased to values similar to those found in the controls after 96 h. All measured enzymes had increased activities in extracts of iron-deficient leaves when compared to the controls and generally decreased to control values 24 h after iron addition. These data provide evidence that organic acid accumulation in iron-deficient leaves is likely not due to an enhancement in leaf carbon fixation. Instead, this accumulation could be associated with organic acid export from the roots to the leaves via xylem.
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PMID:Changes induced by Fe deficiency and Fe resupply in the organic acid metabolism of sugar beet (Beta vulgaris) leaves. 1131 12

The effect of Walker 256 tumour growth on the metabolism of glucose and glutamine in the small intestine of rats was examined. Walker 256 tumour has been extensively used as an experimental model to induce cancer cachexia in rats. Walker 256 tumour growth decreased body weight and small intestine weight and length. The activities of glucose-6-phosphate dehydrogenase and phosphate-dependent glutaminase were reduced in the proximal, median and distal portions of the intestine. Glutamine oxidation was reduced in the proximal portion only. The decrease in glutaminase activity was not due to a low synthesis of the protein as indicated by Western blotting analysis. Hexokinase and citrate synthase activities were not changed by the tumour. These findings led us to postulate that tumour growth impairs glutamine metabolism of small intestine but the mechanism involved remains to be elucidated.
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PMID:Walker 256 tumour growth causes marked changes of glutamine metabolism in rat small intestine. 1197 6

An enhanced susceptibility to infections is well known to occur in a poorly controlled diabetic state. Since glucose and glutamine are essential for lymphocyte function, we investigated whether their metabolism is changed in lymphocytes obtained from mesenteric lymph nodes of alloxan-induced diabetic rats (40 mg/kg body weight). The activities of hexokinase, phosphofructokinase, glucose-6-phosphate dehydrogenase (G6PDH), citrate synthase and phosphate-dependent glutaminase were determined. Decarboxylation of metabolites [U-14C]-, [1-14C]- and [6-14C]-glucose, [1-14C]- and [2-14C]-pyruvic acid, [U-14C]-palmitic acid and [U-14C]-glutamine was evaluated in incubated lymphocytes isolated from mesenteric lymph nodes. The measurements were carried out in cells following three experimental protocols: (1) lymphocytes freshly obtained from control and alloxan-induced diabetic rats, (2) lymphocytes from insulin-treated (2 U/rat per day) diabetic rats and (3) lymphocytes obtained from control and diabetic rats and cultured in the presence of insulin (1 mU/ml) for 6 h. The activities of hexokinase, G6PDH and citrate synthase were decreased by the diabetic state, whereas that of phosphofructokinase was raised. Decarboxylation of [U-14C]- and [6-14C]-glucose, [1-14C]- and [2-14C]-pyruvate and [U-14C]-glutamine were also decreased in lymphocytes from diabetic rats, whereas [U-14C]-palmitic acid decarboxylation was increased. Insulin administration in vivo or added to the culture medium reversed the changes observed in freshly obtained lymphocytes. Alloxan-induced diabetes did change lymphocyte metabolism and this may be an important mechanism leading to impairment of lymphocyte function.
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PMID:Diabetes causes marked changes in lymphocyte metabolism. 1209 63

Nucleated cells are more resistant to complement-mediated cell death than anucleated cells such as erythrocytes. There are few reports concerning the metabolic response of nucleated cells subjected to sub-lethal complement attack. It is possible that the rate of utilization of specific metabolic fuels by the cell is increased to enhance cell defence. We have measured the maximum activity of hexokinase, citrate synthase, glucose 6-phosphate dehydrogenase and glutaminase in rat mesenteric lymphocytes exposed to sub-lethal concentrations of activated complement (present in zymosan-activated serum, ZAS). These enzymes were carefully selected as they indicate changes of flux in glycolysis, TCA cycle, pentose phosphate pathway and glutaminolysis, respectively. The only enzyme activity to change on exposure of lymphocytes to ZAS was glutaminase, which was enhanced approximately by two-fold. Although rates of both glutamine and glucose utilization were enhanced by exposure to ZAS, only the rate of oxidation of glutamine was increased. Complement kills anucleated cells by simple osmotic lysis. However, it is likely that some nucleated cells will display characteristics of an ordered death mechanism and we have demonstrated that the concentration of lymphocyte ATP is dramatically decreased by activated complement. Nevertheless, the extent of cell death could be significantly reduced by the addition of inhibitors of the nuclear enzyme poly (ADP-ribose) polymerase (PARP). We conclude that glutamine metabolism is not only important for lymphocyte proliferative responses but is also important for cell defence from sub-lethal concentrations of activated complement. The rapid rate of complement-induced lymphocyte death reported here is suggested to be a consequence of over-activation of the nuclear enzyme PARP and ATP depletion.
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PMID:Sub-lethal concentrations of activated complement increase rat lymphocyte glutamine utilization and oxidation while lethal concentrations cause death by a mechanism involving ATP depletion. 1212 93


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