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)

A protocol for the rapid purification of the glycerol dehydrogenase (glycerol: NAD+ 2-oxidoreductase, EC 1.1.1.6) from the thermophile Bacillus stearothermophilus has been developed using a combination of chromatographic techniques including affinity chromatography on a Sepharose-immobilised triazine dye (Procion red, HE3B, ICI). Substrate specificity has been examined and Km values determined. The protein has been shown to have an oligomeric Mr of approx. 180,000 and consists of four identical subunits of Mr 42,000. Exposure to chelating agents (e.g., EDTA) leads to total loss of activity; the EDTA-inactivated enzyme can be reactivated by Zn2+ and requires 1 mol equivalent of zinc per subunit for full catalytic activity. Other divalent cations such as Cd2+ and Co2+ will reactivate the apo-enzyme but yields an enzyme of lower specific activity. The enzyme binds 1 equivalent of NADH per subunit and during catalysis transfers the 4-pro-R hydride from the nicotinamide ring of the reduced-coenzyme to the substrate. Glycerol increases the dissociation constant for the interaction between NADH and Zn-metallo-glycerol dehydrogenase (ZnGDH) but has no effect on the equilibrium between NADH and metal-depleted enzyme.
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PMID:Isolation and characterisation of the glycerol dehydrogenase from Bacillus stearothermophilus. 249 67

A study was made of the effect of alimentary deficiency of niacin and of exogenous nicotinamide (500 mg/kg) on the activity of the key enzymes of the pentose phosphate pathway and NADP-dependent malate and isocitric dehydrogenase in the epididymal fatty tissue of rats. It is established that vitamin depletion in the animals' body brings about a 3-fold decrease in the content of NADP+ and a 1.7-fold decrease in the content of NADPH, a 43-percent inhibition of the activity of glucose 6-phosphate dehydrogenase and a 39-percent reduction with respect to transketolase. Nicotinamide suppresses the activity of glucose 6-phosphate dehydrogenase by 35% and that of isocitric dehydrogenase by 40% 12 hours after intraperitoneal injection. It is suggested that NADPH production in the fatty tissue of rats undergoes appreciable changes under the effect of niacin.
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PMID:[The role of niacin in regulating the pentosophosphate pathway and production of NADP-H in fatty tissue]. 253 4

Immature caput epididymal sperm accumulate calcium from exogenous sources at a rate 2- to 4-fold greater than mature caudal sperm. Calcium accumulation by these cells, however, is maximal in the presence of lactate as external substrate. This stimulation of calcium uptake by optimum levels of lactate (0.8-1.0 mM) is about 5-fold in caput and 2-fold in caudal sperm compared to values observed with glucose as substrate. Calcium accumulation by intact sperm is almost entirely mitochondrial as evidenced by the inhibition of uptake by rotenone, antimycin, and ruthenium red. The differences in the ability of the various substrates in sustaining calcium uptake appeared to be related to their ability to generate NADH (nicotinamide adenine dinucleotide). Previous reports have documented that mitochondrial calcium accumulation in several somatic cells is regulated by the oxidation state of mitochondrial NADH. A similar situation obtains for bovine epididymal sperm since calcium uptake sustained by site III oxidation of ascorbate in the presence of tetramethyl phenylenediamine and rotenone was also stimulated by NADH-producing substrates, including lactate, and inhibited by substrates generating NAD+ (nicotinamide adenine dinucleotide, oxidized form). Further, calcium uptake by digitonin-permeabilized sperm in the presence of succinate was stimulated when NADH oxidation was inhibited by rotenone. The compounds alpha-keto butyric, valeric, and caproic acids, which generate NAD+, inhibited the maximal calcium uptake observed in the presence of succinate and rotenone, and the hydroxy acids lactate and beta-hydroxybutyrate reversed this inhibition. These results document the regulation of sperm calcium accumulation by the physiological substrate lactate, emphasize the importance of mitochondria in the accumulation of calcium by bovine epididymal sperm, and suggest that the mitochondrial location of the isozyme LDH-X in mammalian sperm may be involved in the regulation of calcium accumulation.
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PMID:Calcium uptake by bovine epididymal spermatozoa is regulated by the redox state of the mitochondrial pyridine nucleotides. 275 74

During postnatal development, gamma-glutamyl transpeptidase (gamma-GT), reduced glutathione (GSH), and L-glutamic acid (L-Glu) were assayed in the epididymides of rats at 5-day intervals between 10 and 60 days of age and compared to adult levels. gamma-GT activity (with gamma-glutamyl-p-nitroanilide as substrate) and L-Glu (nicotinamide adenine dinucleotide conversion-dependent assay) were measured photometrically, while GSH (o-phthalaldehyde reaction) was quantified with a fluorometric assay. In immature rats, the epididymal gamma-GT was very low but increased after 25 days of age in the caput and after 50 days of age in the cauda. The enzyme level in the epididymal caput was by far the highest in the adult rat reproductive tissues. The postnatal increase of gamma-GT in epididymal caput and cauda was associated with a decline of its substrate GSH and an accumulation of the product L-Glu. These observations provide evidence for the in vivo hydrolytic activity of gamma-GT and explain the high levels of L-Glu found in the epididymis of rats and other mammals.
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PMID:Gamma-glutamyl transpeptidase, glutathione, and L-glutamic acid in the rat epididymis during postnatal development. 290 Jun 57

Histochemical studies of the rat epididymis after treatment with alp ha-chlorohydrin (U-5897) are presented. 14 sexually mature male rats received either daily subcutaneous injections of 50 mg U-5907/kg body weight or distilled water for 20 days. The animals were sacrificed the day following the last injection. U-5897 induced temporary sterility as demonstrated by blocked transport of spermatozoa, and spermatogenic cells eliminated from the spermatogenic epithelium which became blocked in the caudal part of the epididymis. This resulted in the distension of the segment of the distal part of the epididymal duct and to the thinning of the epithelium which lined the altered segment. Alkaline and acid phosphatases, nonspecific esterases, succinate and glucose-6-phosphate dehydrogenases and reduced nicotinamide-adenine dinucleotide tetrazolium reductase in the unchanged part of the epididymal duct were comparable to control rats whereas the altered part of the epididymis showed these activities to much weaker degrees or to be absent altogether.
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PMID:Histochemical studies of the rat epididymis after treatment with alpha-chlorohydrin (U-5897). 415 41

Factors influencing the utilization of ketone bodies by mouse adipose tissue in vitro were studied. Epididymal fat pads can oxidize DL-Beta-hydroxybutyrate-3-(14)C and acetoacetate-3-(14)C to (14)CO(2) as well as convert these compounds to fatty acid-(14)C. An increased output of (14)CO(2) from Beta-hydroxybutyrate-3-(14)C was noted in response to glucose plus insulin, succinate, oxaloacetate, L-asparate, and L-malate. Fatty acid synthesis from Beta-hydroxybutyrate was enhanced by glucose plus insulin, L-aspartate, L-malate, oxaloacetate, and citrate. Nicotinamide stimulated the oxidation of Beta-hydroxybutyrate but not of acetoacetate to CO(2), and did not affect fatty acid synthesis from either ketone body. Nicotinamide increased NAD(+) and NADP(+) levels in epididymal fat pads without affecting the concentration of NADH and NADPH. "Superlipogenesis" caused by fasting the mice for 48 hr and re-feeding them for 24 hr sharply enhanced CO(2) output and lipogenesis from Beta-hydroxybutyrate. The activities of glucose-6-phosphate dehydrogenase, 6-phosphogluconic dehydrogenase, NADP-malic dehydrogenase, and citrate cleavage enzyme from mouse adipose tissue were increased during "superlipogenesis." Free fatty acid release by epididymal fat pads in vitro was slightly increased by Beta-hydroxybutyrate. The relationship of ketone body metabolism and lipogenesis in adipose tissue is discussed.
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PMID:Factors influencing the utilization of ketone bodies by mouse adipose tissue. 422 Nov 4

1. The effect of dinitrophenol on the metabolism of glucose labelled with (14)C and tritium by epididymal fat-pad segments from fed rats was studied. Dinitrophenol at concentrations of 0.1-0.3mm: (a) had little effect on glucose utilization; (b) depressed synthesis of fatty acids and greatly increased that of lactate; (c) increased the T/(14)C ratio in fatty acids synthesized from [U-(14)C,3-T]glucose and decreased that in fatty acids synthesized from [U-(14)C,4-T]glucose; (d) abolished randomization of (14)C from [6-(14)C]glucose in lactate. 2. Dinitrophenol stimulated oxidation of pyruvate and greatly inhibited the oxidation of lactate. It inhibited lipogenesis from pyruvate and lactate. 3. From the isotope data it was calculated that: (a) dinitrophenol stimulates oxidation via the tricarboxylic acid cycle three- to six-fold; (b) dinitrophenol depresses markedly the operation of the pentose cycle; (c) in the presence of dinitrophenol, NADPH formed in the pentose cycle provides all the hydrogen equivalents for fatty acid reduction, whereas, in its absence, NADPH provides 50-70% of the hydrogen equivalents; (d) in the presence of dinitrophenol, there is an excess of ATP produced in the cytoplasm, which flows into the mitochondria. A reverse flow operates in the absence of dinitrophenol. 4. A balance of formation and utilization of reduced nicotinamide nucleotides in the cytoplasm was established. With dinitrophenol there is some excess of NADH. There are indications that this excess may be transferred into mitochondria in the form of malate. 5. Our results are interpreted to indicate the absence from adipose tissue of the alpha-glycerophosphate shuttle for transferring reducing equivalents from the cytoplasm to mitochondria. 6. The effects of dinitrophenol are accounted for in terms of decreased ATP concentrations in the cells, leading to marked decrease in pyruvate carboxylation in the mitochondria and depression of fatty acid synthesis in the cytoplasm.
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PMID:The effect of 2,4-dinitrophenol on adipose-tissue metabolism. 438 39

In order to study the quantitative relationship between fatty acid synthesis and pentose phosphate-cycle activity under different hormonal and dietary conditions affecting the extent of glucose uptake, cells isolated from rat epididymal adipose tissue were incubated in bicarbonate buffer containing [U-(14)C]-, [1-(14)C]- or [6-(14)C]-glucose. From the amount of glucose taken up, the production of lactate and pyruvate, and the incorporation of (14)C from differently labelled [(14)C]glucose into CO(2), fatty acids and glyceride glycerol, the rates of glucose metabolism via different pathways and the extent of lipogenesis under various experimental conditions were determined. The contribution of the pentose phosphate-cycle to glucose metabolism under normal conditions was calculated to be 8%. Starvation and re-feeding, and the presence of insulin, caused an enhancement of glucose uptake, pentose phosphate-cycle activity and fatty acid synthesis. Plots of both pentose phosphate-cycle activity and fatty acid synthesis versus glucose uptake revealed that the extent of glucose uptake, over a wide range, determines the rates of fatty acid synthesis and glucose metabolism via the pentose phosphate cycle. A balance of formation and production of nicotinamide nucleotides in the cytoplasm was established. The total amount of cytoplasmic NADH and NADPH formed was only in slight excess over the hydrogen equivalents required for the synthesis of fatty acids, glyceride glycerol and lactate. Except in cells from starved animals, the pentose phosphate cycle was found to provide only about 60% of the NADPH required for fatty acid synthesis. The results are discussed with respect to an overall control of the different metabolic and biosynthetic reactions in the fat-cells by the amount of glucose transported into the cell.
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PMID:Interrelationship and control of glucose metabolism and lipogenesis in isolated fat-cells. Effect of the amount of glucose uptake on the rates of the pentose phosphate cycle and of fatty acid synthesis. 440 62

The antilipolytic activity of homocysteine-thiolactone-nicotinamide (ST22) and in 2-chloro (ST71), 6-chloro (ST82) and 6-hydroxy (ST90) derivatives was investigated by evaluation of serum free fatty acids (FFA) and triglycerides (TG) (in vivo) and FFA release from adipose tissue (in vitro). Increased FFA levels in 17-hr fasted rats at 60 min following treatment with 7 . 10(-4) mol kg-1 p.o. were reduced by 70% (ST22), 60% (ST82) and 18% (ST71), whereas ST90 provoked no change; TG levels showed similar changes. Basal FFA release from epididymal rat adipose tissue at 60 min following treatment with 7 . 10(-4) mol kg-1 p.o. of ST22 and ST82 was reduced by 79 and 45%, respectively. Lipid mobilization induced by noradrenaline (NA) was diversely affected by the compounds according to the tests employed: with in vivo experiments, serum FFA levels were reduced by 60, 70, 10 and 5% at 60 min following treatment with ST22, ST82, ST71 and ST90, respectively (7 . 10(-4) mol kg-1 p.o.; NA bitartrate, 2 mg kg-1 s.c.); in vitro, ST22 produced no change, whereas the other compounds induced a significant mobilization of FFA. The results suggest that: (a) antilipolytic activity can be greatly modified when various substituents capable of influencing either the inductive (-I) or the resonance (+M) effect are introduced into the different positions of the pyridine ring; and (b) the lipolysis experiments did not evince any direct relationship between the effects obtained by the in vivo tests and those obtained by the in vitro tests.
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PMID:In vivo and in vitro antilipolytic effects of some various substituted homocysteine-thiolactone-nicotinamides: structure-activity study. 621 81

The paper deals with a regulatory effect of the redox state of nicotinamide coenzymes on glyceroneogenesis in the epididymal fatty tissues involving incorporation of [2-14C] pyruvate into synthetized de novo blood glucose, glycerol and fatty acids of triacyglycerines. Large values of the NAD+/NADH and NADP+/NADPH ratios in cytoplasm and mitochondria promote a high rate of lipogenesis and glucose oxidation processes, which is pronounced in a more intense 14C incorporation into fatty acids than in triacylglycerol glycerols. A decrease in the NAD+/NADH ratio and an increase in the reducing ability of NAD-pairs under fasting intensify glyceroneogenesis in the fatty tissue. The incorporation of [14C] pyruvate into blood glucose in 3.6 times as high, the radioactivity of fatty acids lowers. Nicotinamide administered to animals after fastening inhibits glyceroneogenesis in the fatty tissue, lowering considerably the incorporation of [14C] pyruvate into triacylglycerol glycerol and blood glucose.
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PMID:[Study of the role of nicotinamide coenzymes in the regulation of glyceroneogenesis from pyruvate in rat epididymis fat tissue]. 621 12


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