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)

Non-synaptosomal and synaptosomal mitochondrial membrane-linked enzymatic activities, NADH-cytochrome c reductase rotenone insensitive (marker of the outer membrane) and cytochrome oxidase (marker of the inner membrane), were measured in rat brain hippocampus and striatum immediately after and 1, 4 and 7 days following the induction of complete transient ischemia (15 min) by the four vessel occlusion method. Furthermore citrate synthetase activity was measured with and without Triton X-100 in order to qualitatively evaluate the membrane permeability. Non-synaptosomal mitochondrial membranes showed reduction of both activities only in the late reperfusion phase: NADH-CCRRi decreased in striatal mitochondria after 4-7 days and only after 7 days in the hippocampus. COX activity decreased only in striatal mitochondria 7 days after ischemia. Non-synaptosomal mitochondrial membrane permeability did not show changes. Synaptosomal mitochondria showed a decrease of NADH-CCRRi only at 7 days of reperfusion both in hippocampus and striatum, while COX activity decreased only during ischemia and returned to normal levels in the following days in the two areas considered. In summary, free mitochondria showed insensitiveness to ischemia but they resulted damaged in the late reperfusion phase, while mitochondria from the synaptic terminal showed ischemic damage, partially restored during reperfusion. The striatal mitochondria showed a major susceptibility to ischemia/reperfusion damage, showing changes earlier than the hippocampal ones.
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PMID:Changes in non-synaptosomal and synaptosomal mitochondrial membrane-linked enzymatic activities after transient cerebral ischemia. 787 28

The purpose of this research is to determine possible causes and mechanisms involved in the age-associated decline in mitochondrial activity. We have focused on cytochrome c oxidase because it is comprised of both nuclear and mitochondrial-encoded subunits and may provide some insight into the coordination of the two genomes. In agreement with previous reports, we show an approximate 30% decrease in cardiac cytochrome c oxidase activity at 24 months compared to 6 months with no change in the activity of the nuclear encoded citrate synthase of the mitochondrial matrix. The rate of the mitochondrial protein synthesis as shown by [35S]methionine incorporation decreased approximately 35% in the 24-month-old rat compared to the 6-month-old rat. The decrease in protein synthesis was associated with a 30-50% reduction in the levels of most individually radiolabeled translation products including the COX subunits and specifically, a 23% decrease in COX1 protein steady-state levels according to Western analysis. Similarly, there was a decrease in the mRNA steady-state levels of both nuclear and mitochondrial-encoded subunits of cytochrome c oxidase. These results suggest that a number of different mechanisms are involved in the age-associated decrease in heart mitochondrial activity and these are discussed.
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PMID:Age-associated changes in mitochondrial mRNA expression and translation in the Wistar rat heart. 970 70

We examined whether the relationships between mitochondrial enzyme activity, mitochondrial DNA (mtDNA) and mitochondrial RNA (mtRNA) were conserved in rainbow trout (Oncorhynchus mykiss) tissues that differ widely in their metabolic and molecular organization. The activity of citrate synthase (CS), expressed either per gram of tissue or per milligram of total DNA, indicated that these tissues (blood, brain, kidney, liver, cardiac, red and white muscles) varied more than 100-fold in mitochondrial content. Several-fold differences in the levels of CS mRNA per milligram of DNA and CS activity per CS mRNA were also observed, suggesting that fundamental differences exist in the regulation of CS levels across tissues. Although tissues varied 14-fold in RNA g-1, poly(A+) RNA (mRNA) was approximately 2 % of total RNA in all tissues. DNA g-1 also varied 14-fold across tissues, but RNA:DNA ratios varied only 2.5-fold. The relationship between two mitochondrial mRNA species (COX I, ATPase VI) and one mitochondrial rRNA (16S) species was constant across tissues. The ratio of mtRNA to mtDNA was also preserved across most tissues; red and white muscle had 10- to 20-fold lower levels of mtDNA g-1 but 7- to 10-fold higher mtRNA:mtDNA ratios, respectively. Collectively, these data suggest that the relationship between mitochondrial parameters is highly conserved across most tissues, but that skeletal muscles differ in a number of important aspects of respiratory gene expression ('respiratory genes' include genes located on mtDNA and genes located in the nucleus that encode mitochondrial protein) and mtDNA transcriptional regulation.
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PMID:Inter-tissue differences in mitochondrial enzyme activity, RNA and DNA in rainbow trout (Oncorhynchus mykiss) 981 34

The oxidative capacity of the liver, the heart and skeletal muscles for fatty acids were investigated in preruminant calves fed for 19 d on a milk-replacer containing either coconut oil (CO, rich in 12:0) or tallow (rich in 16:0 and 18:1). Weights of the total body and tissues did not differ significantly between the two groups of animals but plasma glucose and insulin concentrations were lower in the CO group. Feeding on the CO diet induced an 18-fold increase in the hepatic concentration of triacylglycerols. Rates of total and peroxisomal oxidation of [1-14C]laurate, [1-14C]palmitate and [1-14C]oleate were measured in fresh tissue homogenates. Higher rates of total oxidation in liver homogenate and of peroxisomal oxidation in liver, heart and rectus abdominis muscle homogenates were observed with laurate used as substrate. Furthermore, the relative contribution of peroxisomes to total oxidation was 1.9-fold higher in the liver and in the heart with laurate than with oleate or palmitate. Finally, the peroxisomal oxidation rate of oleate was 1.5-fold higher in the hearts of calves fed on the CO diet. Whatever the tissue, citrate synthase (CS, EC 4.1.3.7) and cytochrome c oxidase (COX, EC 1.9.3.1) activities were similar between the two groups of calves but the COX: CS activity ratio was lower in the liver of the CO group. In conclusion, laurate is better catabolized by peroxisomes than long-chain fatty acids, especially in the liver. Elongation of lauric acid after partial oxidation might explain the hepatic triacylglycerol accumulation in calves fed on the CO diet.
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PMID:Effects of dietary coconut oil on fatty acid oxidation capacity of the liver, the heart and skeletal muscles in the preruminant calf. 1065 79

To assess mitochondrial function and test the hypothesis of an underlying oxidative phosphorylation defect in Alzheimer disease (AD), we evaluated the activities of mitochondrial respiratory chain enzyme complexes I+III, complexes II+III, complex IV (cytochrome c oxidase, COX), succinate dehydrogenase, and citrate synthase in the frontal cortex, temporal cortex, hippocampus, and cerebellum of 23 AD patients and 13 normal human brains. The major finding was a significant decrease in COX activity in AD temporal cortex and hippocampus, both whether activities were expressed per noncollagen protein content (49 +/-4.6 versus 78+/-10.8 nmol/min/mg NCP, P = 0.006; 23+/-1.9 versus 48.6+/-8.1 nmol/min/mg NCP, p = 0.003) or corrected for citrate synthase activity (1.6+/-0.2 versus 3+/-0.4, P = 0.001; 0.76+/-0.1 versus 1.76+/-0.26, P = 0.0009). There were no significant differences in the activities of complexes I+III, II+III, and of succinate dehydrogenase in any of the brain regions examined. Our results suggest a specific defect of COX in the AD brain versus the normal human brain, which may contribute to impaired energy generation. Biochemically, the defect is confined to selected brain regions, suggesting anatomic specificity.
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PMID:A selective defect of cytochrome c oxidase is present in brain of Alzheimer disease patients. 1085 95

Previous studies in our laboratory demonstrated significant changes in bovine heart mitochondrial bioenergetics during fetal growth and development. To further understand mitochondrial biogenesis in early human development, the activity and subunit content levels of specific mitochondrial enzymes in fetal and neonatal heart were determined. Comparing early gestation (EG, 45-65 day) later gestation (LG, 85-110 day) and neonate (birth-1 month), specific activity of citrate synthase (CS), a Krebs cycle enzyme showed a 2 fold increase from EG to LG and a 2 fold increase from LG to neonate. Specific activities of complex IV and complex V increased similarly 1.8-2 fold from EG to LG. However during the later fetal period from LG to neonate, complex IV activity increased only 1.3 fold and complex V showed no significant increase. Peptide content of COX-II subunit increased 2 fold from EG to LG and by 3.5 fold from LG to neonate. Levels of COX-IV and ATP synthase alpha subunits were undetectable in EG hearts, clearly detectable in LG heart and 3 fold increased from LG to neonate. Unexpectedly, mitochondrial transcription factor A (mt-TFA) levels were not significantly different during these developmental stages. Mitochondrial DNA (mtDNA) levels increased 1.8 fold from EG to LG, and 3.8 fold increase from EG to neonate and correlated with CS activity levels. In conclusion, these data indicate coordinated regulation of some nuclear-encoded (COX-IV and CS activity) and mitochondrial components (COX-II and mtDNA), and strongly suggest that mitochondrial content increases particularly during the early fetal cardiac development and reveal a distinct pattern of regulation for mt-TFA.
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PMID:Heart mitochondrial DNA and enzyme changes during early human development. 1097 57

Triiodothyronine (T(3)) increases O(2) and nutrient flux through mitochondria (Mito) of many tissues, but it is unclear whether ATP synthesis is increased, particularly in different types of skeletal muscle, because variable changes in uncoupling proteins (UCP) and enzymes have been reported. Thus Mito ATP production was measured in oxidative and glycolytic muscles, as well as in liver and heart, in rats administered T(3) for 14 days. Relative to saline-treated controls, T(3) rats had 80, 168, and 62% higher ATP production in soleus muscle, liver, and heart, respectively, as well as higher activities of citrate synthase (CS; 63, 90, 25%) and cytochrome c oxidase (COX; 119, 225, 52%) in the same tissues (all P < 0.01). In plantaris muscle of T(3) rats, CS was only slightly higher (17%, P < 0.05) than in controls, and ATP production and COX were unaffected. mRNA levels of COX I and III were 33 and 47% higher in soleus of T(3) rats (P < 0.01), but there were no differences in plantaris. In contrast, UCP2 and -3 mRNAs were 2.5- to 14-fold higher, and protein levels were 3- to 10-fold higher in both plantaris and soleus of the T(3) group. We conclude that T(3) increases oxidative enzymes and Mito ATP production and Mito-encoded transcripts in oxidative but not glycolytic rodent tissues. Despite large increases in UCP expression, ATP production was enhanced in oxidative tissues and maintained in glycolytic muscle of hyperthyroid rats.
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PMID:T(3) increases mitochondrial ATP production in oxidative muscle despite increased expression of UCP2 and -3. 1128 59

Gender differences in substrate selection have been reported during endurance exercise. To date, no studies have looked at muscle enzyme adaptations following endurance exercise training in both genders. We investigated the effect of a 7-week endurance exercise training program on the activity of beta-oxidation, tricarboxylic acid cycle and electron transport chain enzymes, and fiber type distribution in males and females. Training resulted in an increase in VO2peak, for both males and females of 17% and 22%, respectively (P < 0.001). The following muscle enzyme activities increased similarly in both genders: 3-beta-hydroxyacyl CoA dehydrogenase (38%), citrate synthase (41%), succinate-cytochrome c oxidoreductase (41%), and cytochrome c oxidase (COX; 26%). The increase in COX activity was correlated (R2 = 0.52, P < 0.05) with the increase in VO2peak/fat free mass. Fiber area, size, and % area were not affected by training for either gender, however, males had larger Type II fibers (P < 0.05) and females had a greater Type I fiber % area (P < 0.05). Endurance training resulted in similar increases in skeletal muscle oxidative potential for both males and females. Training did not affect fiber type distribution or size in either gender.
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PMID:Changes in skeletal muscle in males and females following endurance training. 1140 41

Protein levels of mitochondrial transcription factor A (Tfam) and nuclear- and mitochondrial-encoded subunits of respiratory chain complex IV (COX I and COX IV) as well as citrate synthase activity were analysed in muscle biopsy samples of vastus lateralis in six healthy male subjects before and after 4 weeks of one-legged cycle training. One leg was trained with restricted blood flow. The other leg was trained with the same power profile but with non-restricted blood flow. Tfam, COX I and COX IV levels all increased with training, with no differences observed between the legs. The training-induced increase in citrate synthase activity was greater in the leg trained with restricted blood flow. These findings indicate that changed expression of Tfam protein could be one mechanism of exercise-induced mitochondrial biogenesis. The increases of COX I and COX IV indicate a concurrent increase of nuclear- and mitochondrial-encoded subunits of respiratory enzyme complex IV at the protein level in skeletal muscle in response to increased muscle activity. In this study, it was not possible to demonstrate that the greater energy disturbance induced by reduced blood flow further stimulates the expression of mitochondrial proteins, even though it did cause a greater enhancement of citrate synthase activity in concordance with earlier studies.
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PMID:Mitochondrial transcription factor A and respiratory complex IV increase in response to exercise training in humans. 1169 67

We compared responses of the fast extensor digitorum longus (EDL) and tibialis anterior (TA) muscles in young (15-week) and aging (101-week) male Brown Norwegian rats to 50 days of chronic low-frequency stimulation (CLFS, 10 Hz, 10 hours/day). After 50 days of CLFS, the EDL muscles of the young (22-week) and aging (108-week) rats displayed similar increases in type IIA fibers, relative concentration of myosin heavy chain MHCIIa, elevations in mitochondrial citrate synthase and 3-hydroxyacyl-CoA dehydrogenase activities, and similar decreases in glycolytic enzyme activities (glyceraldehydephosphate dehydrogenase, lactate dehydrogenase). TA muscle in young rats contained a few cytochrome c oxidase negative (COX-) type I fibers. Their number was approximately 2-fold elevated by CLFS. Conversely, aging muscle, which contained a slightly higher amount of COX- fibers than young TA muscle, responded to CLFS with a significant decrease in COX- fibers. The appearance of small COX-positive type I fibers in stimulated aging muscle indicated that regenerating type I fibers "diluted" the COX-deficient fiber population.
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PMID:Adaptive potentials of skeletal muscle in young and aging rats. 1191 26


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