Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P56851 (epididymal)
 11,273 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. Methods are described for the extraction, partial purification and assay of phosphofructokinase in rat epididymal adipose tissue. 2. The enzyme was inhibited by ATP at concentrations above 20mum and by citrate; the enzyme was activated by ADP, AMP, 3',5'-(cyclic)-AMP, phosphate and sulphate. 3. The enzyme lost activity on incubation at 25 degrees or during chromatography on DEAE-cellulose unless fluoride at a concentration of 4mm was present. 4. The significance of these results in relation to the role of glycolysis and citrate in lipogenesis is discussed.
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PMID:Citrate and the regulation of adipose-tissue phosphofructokinase. 422 77

1. Isolated rat epididymal fat-cell mitochondria showed an inverse relationship between ATP content and pyruvate dehydrogenase activity consistent with competitive inhibition of pyruvate dehydrogenase kinase by ADP. At constant ATP concentration pyruvate rapidly activated pyruvate dehydrogenase in fat-cell mitochondria, an observation consistent with inhibition of fat-cell pyruvate dehydrogenase kinase by pyruvate. Pyruvate dehydrogenase in fat-cell mitochondria was also activated by nicotinate (100mum) and by extramitochondrial Na(+) (replacing K(+)) but not by ouabain or insulin. 2. In rat epididymal fat-pads incubated in vitro pyruvate dehydrogenase was activated by addition of insulin in the absence of substrate or in the presence of glucose (10mm) or fructose (10mm). Glucose and fructose activated the dehydrogenase in the absence or in the presence of insulin, and pyruvate also activated in the absence of insulin. It is concluded that extracellular glucose, fructose and pyruvate may activate the dehydrogenase by raising intracellular pyruvate and that insulin may activate the dehydrogenase by some other mechanism. 3. Ouabain (300mum) and medium in which K(+) was replaced by Na(+), activated pyruvate dehydrogenase in epididymal fat-pads. Prostaglandin E(1) (1mug/ml), 5-methylpyrazole-3-carboxylate (10mum) and nicotinate (10mum), which are as effective as insulin as inhibitors of lipolysis and which like insulin lower tissue concentration of cyclic AMP (adenosine 3':5'-cyclic monophosphate), did not activate pyruvate dehydrogenase. Higher concentrations of prostaglandin E(1) (10mug/ml) and nicotinate (100mum) produced some activation of the dehydrogenase. 4. It is concluded that the activation of pyruvate dehydrogenase by insulin is not due to the antilipolytic effect of the hormone and that the action of insulin in lowering adipose-cell concentrations of cyclic AMP does not afford an obvious explanation for the effect of the hormone on pyruvate dehydrogenase. The possibility that the effects of insulin, ouabain and K(+)-free medium may be mediated by Ca(2+) is discussed.
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PMID:Mechanisms regulating adipose-tissue pyruvate dehydrogenase. 465 97

1. Extraction of rat epididymal adipose tissue with buffer containing EDTA yields a pyruvate kinase, provisionally called PyK-A, the properties of which resemble in several respects those of the allosteric pyruvate kinase of liver. These properties include co-operative interactions with phosphoenolpyruvate, Mg(2+), K(+), NH(4) (+) and ATP, and sensitivity to activation by fructose 1,6-diphosphate. 2. Extraction in the absence of EDTA yields predominantly a form, PyK-B, that shows both normal Michaelis-Menten kinetics with phosphoenolpyruvate, Mg(2+) and ATP, and co-operative interactions with K(+) and NH(4) (+); this form is insensitive towards fructose 1,6-diphosphate. 3. Both forms yield simple kinetics with ADP, though K(m) values differ in the two systems. In all cases where co-operativity has been demonstrated, Hill-plot n values are between 1.4 and 2.0. 4. The conversion of PyK-A into PyK-B is mediated specifically by fructose 1,6-diphosphate; the reverse reaction is occasioned by EDTA, ATP or citrate. It is thought that a bivalent cation may be involved in this interconversion. 5. Attempts at partial purification have revealed that the enzyme resembles the pyruvate kinase of skeletal muscle, rather than that of liver, in its solubility in ammonium sulphate and elution from DEAE-cellulose. 6. The relevance of these properties in the regulation of pyruvate kinase activity in vivo in adipose tissue is discussed.
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PMID:Adipose-tissue pyruvate kinase. Properties and interconversion of two active forms. 497 50

1. Methods are described for the extraction and assay of ATP, ADP, AMP, glucose 6-phosphate, l-glycerol 3-phosphate and citrate in rat epididymal adipose tissue incubated in vitro for 1hr. At this time of incubation rates of glucose uptake and outputs of glycerol, free fatty acids, lactate and pyruvate were shown to be constant. 2. In fat pads incubated in medium containing glucose (3mg./ml.) and albumin (20mg./ml.) the concentrations (in mmumoles/g. wet wt.) were: ATP, 70; ADP, 36; AMP, 9.0; glucose 6-phosphate, 3.0; l-glycerol 3-phosphate, 3.3; citrate, 8.1. 3. The volume of intracellular water calculated from ([(3)H]water space-[(14)C]sorbitol space), ([(14)C]urea space-inulin space) and (weight loss on drying-[(14)C]sorbitol space) was 1.4ml./100g. wet wt. of tissue. The intracellular volume was not changed by insulin, alloxan-diabetes or adrenaline. 4. When compared in terms of mumoles/ml. of intracellular water the concentration of ATP in adipose tissue was less than in heart and diaphragm muscles. The concentrations of ADP and AMP were greater both in absolute terms and relative to ATP. Insulin, alloxan-diabetes and adrenaline had no significant effects on the concentrations of the adenine nucleotides in adipose tissue. 5. The concentration of glucose 6-phosphate was increased by insulin and lowered by alloxan-diabetes and adrenaline. The concentration of l-glycerol 3-phosphate was increased by insulin, unchanged by alloxan-diabetes and lowered by adrenaline. The concentration of citrate was increased by adrenaline and alloxan-diabetes and unchanged by insulin. 6. The effect of glucose concentration in the medium on rates of glucose uptake in adipose tissue from normal rats and alloxan-diabetic rats was investigated. The K(u) of glucose uptake was 29-44mg./100ml. and the V(max.) was 0.77mg./g. wet wt. of tissue/hr. Insulin increased the V(max.) and alloxan-diabetes diminished it, but neither agent significantly altered the K(u). 7. The significance of these results in relation to control of metabolism of adipose tissue is discussed.
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PMID:Measurement of concentrations of metabolites in adipose tissue and effects of insulin, alloxan-diabetes and adrenaline. 596 39

Increases in the amount of the active non-phosphorylated form of pyruvate dehydrogenase in rat epididymal adipose tissue, as a result of incubation with insulin, persist not only during the preparation of mitochondria but also during subsequent incubation of coupled mitochondria in the presence of respiratory substrates. No effect on insulin was found if the hormone was added directly to mitochondria in the presence or absence of added plasma membranes. Concentrations of several possible regulators of pyruvate dehydrogenase kinase (ATP, ADP, NADH, NAD+, acetyl-CoA, CoA and potassium) were measured in rat epididymal-adipose-tissue mitochondria incubated under conditions where differences in pyruvate dehydrogenase activity persist as a result of insulin action. No alterations were found, and it is suggested that inhibition of the kinase is not the principal means by which insulin activates pyruvate dehydrogenase. The intramitochondrial concentration of magnesium was also unaffected. Differences in pyruvate dehydrogenase activity in interscapular brown adipose tissue associated with manipulation of plasma insulin concentrations of cold-adapted rats were also shown to persist during the preparation and subsequent incubation of mitochondria in the presence or absence of GDP. It is pointed out that the persistence of the effect of insulin on pyruvate dehydrogenase in incubated mitochondria will facilitate the recognition of the mechanism of this action of the hormone. Evidence that the short-term action of insulin involves an increase in pyruvate dehydrogenase phosphate phosphatase activity rather than inhibition of that of pyruvate dehydrogenase kinase is discussed.
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PMID:Persistence of the effect of insulin on pyruvate dehydrogenase activity in rat white and brown adipose tissue during the preparation and subsequent incubation of mitochondria. 632 Aug 7

Ecto-ATPase in rat cauda-epididymal intact spermatozoa has a high degree of substrate specificity for the hydrolysis of ATP and dATP rather than of ADP, AMP, GTP, dGTP, CTP, dCTP, TTP and UTP. The enzyme is activated by bivalent metal ions in the order Mg2+ greater than Mn2+ greater than Co2+ greater than Ca2+. The apparent Km values of the enzyme for Mg2+, Mn2+, Co2+ and Ca2+ are approx. 80, 100, 100 and 150 microM respectively. Addition of Ca2+ (0.1 or 1 mM) gives no further stimulation of the Mg2+-activated ecto-ATPase activity. The apparent Km value of the enzyme for ATP is 95 microM. Pi (16 mM) inhibits the enzymic activity (by 25%), whereas Na+ (50 mM) or K+ (10 mM) alone or in combination, polyamines (spermine and spermidine; 1--12.5mM) and nucleic acids (yeast RNA and calf thymus DNA; 0.12 or 0.62 mg/ml) had no significant effect on the activity of the enzyme. Orthovanadate at a relatively low concentration (20 microM) strongly inhibits (approx. 50%) the ecto-ATPase activity. Vanadate inhibition can be reversed by noradrenaline (2.5 mM). The vanadate-sensitivity of the enzyme increases markedly during spermatozoal maturation in the epididymis. However, the activity of the spermatozoal ecto-ATPase decreases progressively during the epididymal transit of the testicular spermatozoa.
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PMID:Enzymic characteristics of ecto-adenosine triphosphatase in rat epididymal intact spermatozoa. 645 84

Incremental levels of trilinoelaidate (tt18:2) were fed to rats for 11 weeks and changes in lung and epididymal lipid fatty acid composition were determined, and concentrations of prostanoids in serum, lung and stomach fundus were measured. Platelet aggregation to various agonists was tested. In the lung there was a concomitant increase of linoelaidate corresponding to incremental dietary levels in all lipid classes (phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine-phosphatidylinositol and neutral lipids). Arachidonic acid in lung phosphatidylcholine was markedly decreased. Epididymis accumulated linoelaidate in only the neutral lipid fraction; no tt18:2 was found in any of the phospholipid classes. Serum prostanoid levels (thromboxane B2 and prostaglandins PGF2 alpha and PGE) were significantly decreased in rats fed high levels of tt18:2, but were not altered at lower levels of consumption; the concentrations of 6-keto-PGF1 alpha were not significantly altered at any level of tt18:2. Platelet responsiveness to various agonists was not significantly altered by incremental dietary trilinoelaidate, i.e., ADP, thrombin, collagen and calcium elicited similar aggregation responses. In conclusion, dietary trilinoelaidate at low levels of consumption, while being incorporated into various lipid classes, did not alter serum and tissue prostanoid levels or markedly affect platelet aggregation.
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PMID:Dietary trilinoelaidate: effects on organ fatty acid composition, prostanoid biosynthesis and platelet function in rats. 669 85

1. Dye-ligand chromatography using immobilized Cibacron blue F3GA (blue Sepharose CL-6B) and Procion red HE3B (Matrex gel red A) as matrices and general ligand chromatography employing immobilized 2',5'-ADP (2',5'-ADP-Sepharose 4B) and immobilized 3',5'-ADP (3',5'-ADP-Agarose) were employed for purification of NADPH-dependent 2-enoyl-CoA reductase and 2,4-dienoyl-CoA reductase from bovine liver (formerly called 4-enoyl-CoA reductase [Kunau, W. H. and Dommes, P. (1978) Eur. J. Biochem. 91, 533-544], as well as 2,4-dienoyl-CoA reductase from Escherichia coli. 2. The NADPH-dependent 2-enoyl-CoA reductase from bovine liver mitochondria was separated from 2,4-dienoyl-CoA reductase by dye-ligand chromatography (Matrex gel red A/KCl gradient) as well as by general ligand affinity chromatography (2',5'-ADP-Sepharose 4B/NADP gradient). The enzyme was obtained in a highly purified form. 3. The NADPH-dependent 2,4-dienoyl-CoA reductase from bovine liver mitochondria was purified to homogeneity using blue Sepharose CL-6B, Matrex gel red A, and 2',5'-ADP-Sepharose 4B chromatography. 4. The bacterial 2,4-dienoyl-CoA reductase was completely purified by ion-exchange chromatography on DEAE-cellulose followed by a single affinity chromatography step employing 2',5'-ADP-Sepharose 4B and biospecific elution from the column with a substrate, trans,trans-2,4-decadienoyl-CoA. 5. The application of dye-ligand and general ligand affinity chromatography for purification of NADPH-dependent 2,4-dienoyl-CoA reductases taking part in the beta-oxidation of unsaturated fatty acids is discussed. It is concluded that making use of coenzyme specificity for binding and substrate specificity for elution is essential for obtaining homogeneous enzyme preparations.
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PMID:Purification by affinity chromatography of 2,4-dienoyl-CoA reductases from bovine liver and Escherichia coli. 674 95

Rats were fed diets containing various amounts of added thiram, a dithiocarbamate fungicide. As thiram feeding resulted in decreased appetite, control rats not receiving thiram were pair-fed to the experimental ones. On d 30 of the experiment the animals were weighed and sacrificed, and the following organs were weighed: liver, kidneys, heart, epididymal and perirenal fat pads, testes, seminal vesicles, tibia, adrenals, and thyroid. Liver concentrations of lactate, pyruvate, beta-hydroxybutyrate, acetoacetate, ATP, and ADP were determined by enzymatic-spectrofluorimetric assay. For each parameter studied and each thiram dosage, values for treated rats were compared to those for control rats and the probability under the null hypothesis was computed. These probabilities were transformed into probits, logits, or "Weibull transforms" and plotted against the logarithms of the respective doses. Models were fitted to the data by linear regression techniques. Finally, the dose inducing the least significant difference (LSD dose), and the dose considered "safe" at P = 0.95, 0.99, and 0.999 were calculated. Significant pesticide-induced changes in the following parameters were found: food intake; weights of the whole body, kidneys, epididymal and perirenal fat pads, testes, and seminal vesicles; and liver beta-hydroxybutyrate/acetoacetate and lactate/pyruvate ratios. As the models did not differ in fit to the experimental data or in computed LSD doses, they were discriminated on the grounds of their underlying theoretical assumptions and their prediction of safe doses in a long-term study. The log-probit model was rejected for the former reason, and it was shown that the Weibull model foresees a nonnegligible risk of change, with thiram feeding at low doses, for too many parameters. The analysis resulted in the selection of the log-probit model for further use. Weight of fatty tissues was the most sensitive parameter and, using the log-probit model, the predicted no-effect dose at the 95 percent confidence level was 38 ppm thiram in the diet.
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PMID:Dietary no-effect level of a dithiocarbamate fungicide, thiram, evaluated from measurement data on rats. I. Choice of the model of the dose-response relationship. 739 1

A systematic investigation of potential ligands for the affinity purification of aldehyde reductase (alcohol:NADP+ oxidoreductase, EC 1.1.1.2.) has been carried out. The most suitable nucleotide ligands tested were NADP+ and 2',5'-ADP. Adsorbed enzyme could be eluted with NADPH but not NADH. The chlorotriazinyl dyes Cibacron Blue F3GA and Procion Red HE3B also proved effective as 'affinity' ligands when immobilized to Sepharose 4B. The free dyes and also Blue Dextran (Cibacron Blue F3GA coupled to dextran) were all potent inhibitors of aldehyde reductase. The inhibition by Blue Dextran was shown to be competitive with respect to NADPH (Ki = 1.8 x 10(-7) M). The enzyme was sensitive to inhibition by glutaric acid derivatives, flavonoids and a range of anti-convulsants.
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PMID:Isolation and characterization of rat liver aldehyde reductase. 744 91


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