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)

The maximal rate of some cerebral enzymatic activities related to energy transduction (hexokinase; phosphofructokinase; lactate dehydrogenase; citrate synthase; malate dehydrogenase; total NADH-cytochrome c reductase; cytochrome oxidase), amino acid metabolism (glutamate decarboxylase; glutamate dehydrogenase) and cholinergic metabolism (acetylcholine esterase) were tested in the cerebral cortex and in sub-cortical area of rats. The evaluations were performed both in the homogenate in toto and in the crude mitochondrial fraction, before and after a postdecapitative normothermic ischemia of 5, 10, 20, and 40 min duration. The results are discussed also with respect to the pharmacological pretreatment with two biological substances which may modulate amino acid (L-alanine) and phospholipid metabolism (CDP-choline). The analysis of the present data suggests the occurrence in brain tissue of a variety of interrelated factors implicated in the ischemia-induced changes of the maximal rate of the enzymatic activities related to the energy transduction. These include: (a) rearrangement of the enzymatic activities because of the changed metabolic and chemico-physical condition; (b) decrease in the activity of enzymes related to the electron transfer chain and glycolysis; (c) changes in enzymes related to mitochondrial membranes. The effects of in vivo administration of alanine or CDP-choline, even if significant, are not consistent throughout the time period studied.
 ...
PMID:Changes induced by ischemia on some cerebral enzymatic activities related to energy transduction and amino acid metabolism. 685 30

Commonly the TCA cycle fulfils an anabolic and a catabolic function in case of aerobic chemoorganoheterotrophic nutrition. In methylotrophic growth the TCA cycle is dispensable as a bioenergetic pathway. This is reflected by properties of citrate synthase in facultative methylotrophic bacteria. Two citrate synthases, a "chemoorganoheterotrophic" one, which is inhibited by NADH (or ATP in Acetobacter MB 58), and a "methylotrophic" one, which is not or less affected by energy indicators, were found in Pseudomonas oleovorans, Pseudomonas MS, Pseudomonas MA, and Acetobacter MB 58. The concentration of these citrate synthases depends on the manner of nutrition. Bacteria with ICL-negative-variant of the serine pathway and with ribulosebisphosphate pathway seem to possess only a "chemoorganoheterotrophic" citrate synthase. Possibly the anabolic function of this citrate synthase can be realized by metabolites.
 ...
PMID:[Regulation of citrate synthase in facultative methylotrophic bacteria]. 688 Feb 50

The activity of 22 enzymes of energy metabolism was determined in m. vastus lateralis quadricipitis of 14 adolescents aged 13-15 years (7 girls) and 14 adults aged 22 to 42 years (7 female subjects). The measurements were performed kinetically, at 37 degrees C, using optimal or near-to-optimal procedures. With the exception of one enzyme, enolase, no differences between sexes were observed in the two age groups. Glycolytic enzymes, including fructose-6-phosphate kinase, showed no significant differences in their activity in adults as compared to adolescents. The activity of enolase was lower in females of both age groups, but no difference due to age was found in this respect. Of the oxidative enzymes studied, only citrate synthase showed no significant difference in adults vs adolescents, whereas the activities of lipoamide dehydrogenase (+ 40%), NADP-isocitrate dehydrogenase (+ 44%), fumarase (+ 24.5%), total malate dehydrogenase (+ 42.2%) and NADH-dehydrogenase (+ 39%) were all significantly higher in the latter group. Aspartate aminotransferase was also 44% higher in adolescents. The possible physiological importance of these observations is discussed with regard to the functional capacity of the skeletal muscle. The hypothesis was considered that adolescents of this age may have a glycolytic capacity comparable to adults, but that they may oxidize pyruvate at a rate higher than adults.
 ...
PMID:Enzyme activities in skeletal muscle of 13-15 years old adolescents. 705 78

Kinetic studies of the individual reaction of pig heart pyruvate dehydrogenase complex (pyruvate dehydrogenase (pyruvate:lipoamide oxidoreductase (decarboxylating and acceptor-acetylating), EC 1.2.4.1); dihydrolipoamide reductase(NAD+) (NADH:lipoamide oxidoreductase, EC 1.6.4.3); dihydrolipoamide acetyltransferase (acetyl-CoA:dihydrolipoamide S-acetyltransferase, EC 2.3.1.12)), citrate synthase (citrate oxaloacetate-lyase (pro-3S-CH2COO- leads to acetyl-CoA), EC 4.1.3.7) and the pyruvate dehydrogenase complex-citrate synthase coupled system show that the KmCoA value of pyruvate dehydrogenase complex and KmCoASAc value of citrate synthase decrease in the coupled system when compared to those in the individual enzyme reactions. The explanation for this interaction may be an association between the two enzymes. When it was centrifuged with 150 000 x g for 140 min, 30% of the citrate synthase sedimented in the presence of the pyruvate dehydrogenase complex, while no sedimentation was observed in the absence of the pyruvate dehydrogenase complex. Sedimentation of cytoplasmic malate dehydrogenase, phosphotransacetylase, hemoglobin and Blue albumin were negligible under the same condition. In gel chromatography experiments a significant peak of citrate synthase activity co-migrated with the pyruvate dehydrogenase complex peak. This observation also suggests the possible association of two enzymes.
 ...
PMID:Interaction between the pyruvate dehydrogenase complex and citrate synthase. 721 36

The effect of the chronic intramuscular administration of some agents related to the S-adenosyl-L-methionine system on the hyperammonemia syndrome was evaluated. This experimental syndrome was induced in the rat by intraperitoneal administration of high doses of ammonium acetate (33, 100 and 300 mg/kg/day, 6 days a week for 80 days) followed by the assay of the activities of some cerebral enzymes involved in energy transduction. The enzymatic activities studied in the homogenate and in the mitochondrial fractions of brain tissue were: lactate dehydrogenase, citrate synthase, malate dehydrogenase, total NADH-cytochrome c reductase and cytochrome oxidase. All three doses of ammonium acetate induced significant modifications in the cerebral enzymatic activities. These doses reduced the activity of the total NADH-cytochrome c reductase both in the homogenate and in the mitochondrial fraction. On the other hand the activity of malate dehydrogenase was reduced limited to the two lower doses in the homogenate only. The simultaneous daily treatment (i.m.) with equimolar doses of substances involved in the S-adenosyl-L-methionine system (adenosine, methionine and S-adenosyl-L-methionine) did not cause any significant modification of the cerebral enzymatic activities associated with the administration of ammonium acetate at the three dose levels, thus confirming our previous results.
 ...
PMID:Cerebral enzymatic activities during chronic hyperammonemia and treatment with S-adenosyl-L-methionine, adenosine and methionine in the rat. 725 Mar 59

[14C]Acetyl-CoA was found to react spontaneously with dithiothreitol to give a relatively apolar product which was readily extractable into a butanol-toluene scintillant. This technique was used in rapid, reproducible assay for rat brain ATP:citrate lyase using [1,5-14C]citrate as substrate. The tissue extract, a 14,000 g supernatant, exhibited a lyase activity of approximately 7 nmol acetyl-CoA produced/min per mg supernatant protein, and was inhibited greater than or equal to 79% by alpha-ketoglutaric acid (10 mM), Cu2+ (1 mM) and Zn2+ (1 mM). [14C]Oxaloacetate, [14C]malate and endogenous citrate synthase were found not to interfere significantly with lyase estimations, but NADH was required in the reaction mixture to inhibit acetyl-CoA hydrolase activity.
 ...
PMID:The interaction of dithiothreitol and acetyl coenzyme A in a radiochemical assay for rat brain ATP:citrate oxaloacetate lyase. 725 96

The effect of a chronic (3 months) treatment with vincamine on the enzymatic activities related to energy transduction was studied on several areas of the cerebral cortex of dog brain. About enzymatic activities of the four different cortical areas, in controls, no difference was observed between the enzymatic activities evaluated in the crude mitochondrial fraction, with regard to both the tricarboxylic acid cycle (citrate synthase, malate dehydrogenase) and the electron transport chain (total NADH-cytochrome c reductase, cytochrome oxidase). On the contrary, in the homogenate, lactate dehydrogenase, malate dehydrogenase and acetylcholine esterase showed different maximal activities. In the crude mitochondrial fraction the intravenous treatment with the three different doses of vincamine failed to cause any significant change as compared to controls. On the contrary, with regard to the enzymatic activities evaluated in the homogenate in toto, the analysis of variance revealed an effect on cytochrome oxidase at the dose of 3 mg/kg intravenously.
 ...
PMID:Effect of vincamine on some enzymatic activities from various areas of the beagle dog cerebral cortex. 729 73

Dose/action and time/action relationships relative to the effect of the in vivo treatment with some biological molecules (cytidine, uridine and glutamine) on several enzymatic activities connected with cerebral metabolism (lactate dehydrogenase, malate dehydrogenase, total NADH cytochrome c reductase, cytochrome oxidase and citrate synthase) were studied in the normal rat brain. While time/action curves were found to be in agreement with classical pharmacodynamic descriptions, dose/action curves exhibited a varying behavior according to the biological substrate tested (brain homogenate in toto or crude mitochondrial fraction from brain in toto). Often enzymatic activity changes as a function of dose failed to show linear correlations, a parabolic pattern being observed. At any rate, the changes affecting several cerebral enzymatic activities may account for some pharmacodynamic properties of the biological molecules tested.
 ...
PMID:Dose/action and time/action relationships of some biological molecules evaluated on the cerebral enzymatic activities. 745 24

The changes induced by alphaxalone-alphadolone (3:1) in the cerebral enzymatic activities of the Kreb's cycle (citrate synthase, malate dehydrogenase) and electron transfer chain (total NADH-cytochrome c reductase and cytochrome oxidase) were studied. In addition, the activation of lactate dehydrogenase (for the glycolytic pathway) and of acetylcholine esterase (as indicative of transmission) were investigated. These enzymatic activities were evaluated in the homogenate in toto and/or in the crude mitochondrial fraction of rat brain, since these enzymes are variously located in the cytoplasm. Two relationships were studied: a) dose/action (0.5, 1. 2, 4, 8, 16 and 32 mg . kg-1) by measurements carried out 60 min after i.p. administration; b) time/action (16 mg . kg-1 i.p.; measurements 15, 30, 60, 120 and 240 min after administration). The results show that in both kinds of trials alphaxalone-adphadolone reduced only the activity of the enzyme cytochrome oxidase evaluated on the brain homogenate in toto. More specifically, with regard to the dose/action relationship, the effect occurred starting with the dose of 2 mg . kg-1 and did not take place linearly with the higher ones. As to the time/action relationship, the effect began 60 min after administration, the changes being observed also at the subsequent times. The data obtained are discussed with regard to the interactions between alphaxalone -alphadolone and mitochondrial enzymatic systems, and compared with the effects of phenobarbital on the same systems.
 ...
PMID:Effect of alphaxalone-alphadolone on some enzymatic activities from rat brain. 745 57

Insulin resistance in skeletal muscle is associated with 1) relative increases in the proportion of glycolytic and fast-twitch muscle fibers and decreases in the proportion of more oxidative fibers and 2) a higher proportion of the saturated fatty acids in membrane structural lipids. Exercise is known to improve insulin action. The aims of the current studies were 1) to investigate the relationship between muscle fiber type and membrane fatty acid composition and 2) to determine how voluntary exercise might influence both variables. In sedentary Wistar rats in experiment 1, increased amounts of unsaturated fatty acids were found in the more oxidative insulin-sensitive red quadriceps and soleus muscles, whereas reduced levels of polyunsaturated fatty acids were found in primarily glycolytic white quadriceps muscles. In experiment 2, voluntary running-wheel exercise by adult female rats over 45 days resulted in reduced proportions of type IIb fibers (P = 0.01) and increased proportions of type IIa/IIx fibers (P = 0.03) in extensor digitorum longus muscle. The magnitude of these changes was related to the distance run (r = -0.73, P = 0.04; r = 0.79, P = 0.02, respectively). Exercise significantly increased oxidative capacity, as assessed by the proportion of intensely NADH-stained fibers (P = 0.0004) and citrate synthase (P = 0.003) and hexokinase (P = 0.04) activities. Citrate synthase activity was also increased by exercise in soleus muscle, where, as expected, no fiber type changes were detected. No significant differences in the fatty acid profile of soleus and extensor digitorum longus were found between groups.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Relationships between muscle membrane lipids, fiber type, and enzyme activities in sedentary and exercised rats. 750 5


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>