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:3.6.1.3 (ATPase)
65,361 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Zinc, lead and cadmium in the form of chloride salts when added to a standard assay system containing 80 X 10(-6) ejaculated washed human spermatozoa caused a dose and duration-dependent inhibition of their motility. The activity of certain key enzymes of carbohydrate and energy metabolism, viz, glycogen phosphorylase, glucose-6-phosphatase, fructose-1, 6-diphosphatase, glucose-6-phosphate isomerase, amylase, Mg2+- dependent ATPase and lactic and succinic acid dehydrogenases were also found to be inhibited. The order of inhibitory effects of the heavy metals were zinc less than lead less than cadmium. The metal chelating agent, ethylene diamine tetra-acetic acid (EDTA, disodium salt) also interfered with the spermatozoal motility and inhibited the enzyme activities.
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PMID:Effect of selected metal ions on the motility and carbohydrate metabolism of ejaculated human spermatozoa. 314 74

The preparation of a purified fraction of ram sperm plasma membranes is described and validated in this paper. Lipid analyses were performed on both the membrane preparation and whole spermatozoa; the main differences were that plasma membranes showed a significantly higher cholesterol: phospholipid molar ratio and a higher sphingomyelin content than did whole spermatozoa, but a lower proportional content of phosphatidylethanolamine. Enzymic assays revealed the presence of two distinct adenosine triphosphatase (ATPases) in the membrane fraction, activated independently by calcium and sodium ions. Arrhenius plots of the calcium-stimulated ATPase activity demonstrated that a change in energy of activation occurred in the region of 23 degrees C; it is believed that this is evidence for the occurrence of a thermal phase transition in the lipid environment of the enzyme molecules.
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PMID:Determination of lipid composition and thermal phase transition temperature in an enriched plasma membrane fraction from ram spermatozoa. 315 98

Effects of alcoholic seed extract of Abrus precatorius Linn. were investigated at a dose of 100 mg/Kg body wt./day/rat for 60 days on fertility, semen profile and sperm metabolism of orally administered sexually mature male albino rats using WHO protocols. Serum testosterone levels were also measured using RIA technique. The data revealed that the cauda epididymal sperm motility was significantly lowered with no effect in its sperm concentration by 60 days of feeding. The scanning electron microscopic study on sperm morphology exhibited decapitation, acrosomal damage and formation of bulges on midpiece region of sperms in treated rats. The biochemical studies on epididymal spermatozoa indicated alterations in their energy and/or oxidative metabolism as evidenced by a fall in succinate dehydrogenase and ATPase levels by extract allocation. It did not exert any effect in body and organ weights. But an average number of implantation sites in females after mating with the treated male rats markedly declined. Contrarily, a significant increase in serum testosterone levels was noted by 60 days of administration. Thus, the decrease in fertility rate in extract receiving animals is correlated with reduced sperm motility, metabolism and altered sperm morphology in epididymis.
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PMID:Antifertility effects of alcoholic seed extract of Abrus precatorius Linn. in male albino rats. 343 10

Treatment of bull spermatozoa from epididymal cauda with 5 micrograms digitonin per microliter cells removed the permeability barrier of plasma membrane for mitochondrial substrates and effectors. Such preparations yielded a high portion of coupled mitochondria characterized by ratios of active respiration to carboxyatractyloside-inhibited respiration greater than 13 in the presence of efficient substrates. Bull sperm mitochondria oxidized pyruvate and lactate in the presence of malate as well as glycerol-3-phosphate with much higher rates than succinate or palmitoyl carnitine. For the efficient substrates the respiration coupled to ADP phosphorylation amounted to 77 to 100% of the uncoupled rate. Comparable rates of active respiration were also observed with ATP indicating the high ATPase activity present in digitonin-treated spermatozoa. Uncoupled rates of respiration corresponded to rates of intact spermatozoa, but the capacity of the phosphorylating respiration exceeded the respiration rates of intact motile spermatozoa remarkably. This indicates that the spermatozoal ATP turnover at sufficient supply of substrate is mostly controlled by ATP utilizing reactions.
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PMID:Capacities of oxidative metabolism in digitonin-treated bovine epididymal spermatozoa. 356 16

Particles found in bovine seminal vesicle secretion were enriched by centrifugation. They varied in size and morphology and contained Mg2+,Ca2+-activated ATPase, aminopeptidase A, alanyl aminopeptidase, gamma-glutamyl transpeptidase and dipeptidyl peptidase IV activities. Hyperactivation of sperm motility and the acrosome reaction were induced by these particles in epididymal spermatozoa suspended in a modified Ringer medium. The hyperactivation, analysed with a microscopic slide test, started within minutes of exposure to membrane particles and continued for 3-4 h, during which time spermatozoa underwent the acrosome reaction. Acrosome staining, phase-contrast microscopy and transmission electron microscopy revealed that the acrosome reaction started within 60 min at 37 degrees C and affected up to 80% of spermatozoa in 4 h. These membrane particles differed from those reported previously in other species in enzyme composition, function and organ of origin.
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PMID:Effect of secretory particles in bovine seminal vesicle secretion on sperm motility and acrosome reaction. 357 75

The regulation of oxidative phosphorylation was studied with digitonin-treated epididymal bull spermatozoa in which mitochondria are directly accessible to low molecular compounds in the extracellular medium. Due to the high extramitochondrial ATPase activity in this cell preparation, it was possible to stimulate respiration to a small extent only by added hexokinase in the presence of glucose and adenine nucleotides. Added pyruvate kinase plus phosphoenol pyruvate, however, strongly suppressed the respiration. Under these conditions, the respiration was found to depend on the extramitochondrial [ATP]/[ADP] ratio in the range of 1-100. The contribution of the adenine nucleotide translocator to this dependence was determined by titration with the irreversible inhibitor carboxyatractyloside in the presence of ADP. Using lactate plus malate as substrate, the active state respiration was controlled to about 30% by the translocator, whereas 12 and 4% were determined in the presence of L-glycerol-3-phosphate and malate alone, respectively. In order to compare the results with those for intact cells, the adenine nucleotide patterns were determined in intact and digitonin-treated spermatozoa under conditions of controlled respiration in the presence of vanadate and carboxyatractyloside, respectively. About 21% of total cellular adenine nucleotides were found in digitonin-treated cells representing the mitochondrial compartment. While allowing for the intramitochondrial amount of adenine nucleotides, the cytosolic [ATP]/[ADP] ratio was estimated to be 6-times higher than the mitochondrial ratio in intact cells. It is concluded from the data presented that the principal mechanism by which oxidative phosphorylation in sperm mitochondria is regulated via the extramitochondrial [ATP]/[ADP] ratio is the same as that demonstrated for other isolated mitochondria.
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PMID:Regulation of oxidative phosphorylation in mitochondria of epididymal bull spermatozoa. 360 41

Eight adult Landrace boars were housed for 12 months in one of two social environments. Socially nonrestricted boars were penned near estrual females and socially restricted boars were penned behind solid walls to eliminate visual and physical contact with other pigs. All animals were subjected to natural changes in day length. The sensitivity of ejaculated spermatozoa to ouabain (in inhibitor of Na+-K+ ATPase) was determined on 4 consecutive weeks in November, March-April, and July-August. Semen was diluted in Tyrode's solution (pH 7.4) with and without 10(-3) M ouabain. Duplicate samples of control and ouabain-treated spermatozoa were incubated at 37 degrees C for 4 h, and percent motile sperm, motility type, and motility index (combination of percent and type) were determined at hourly intervals. Ouabain-induced decreases in most motility parameters varied with season (season X treatment, P less than 0.05). At hour 4, induced decreases in percent motile sperm were more pronounced in November and July-August than in March-April for socially nonrestricted boars. Decreases in motility type were greater (P less than 0.05) in November and July-August than in March-April for socially nonrestricted boars and were greater (P less than 0.01) in November than in July-August for restricted boars. In March-April motility type decreased (P less than 0.01) to a greater extent for socially restricted vs. nonrestricted boars. Similar season and social environment differences were observed for motility index values. Given the interrelationships between ouabain sensitivity, the functional integrity of sperm cells, and fertilizing capacity, season and social environment differences in ouabain-induced motility depression probably reflect qualitative changes in boar spermatozoa.
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PMID:Season and social environment influence the membrane integrity of ejaculated boar spermatozoa as assessed by ouabain sensitivity. 379 Oct 41

The dependence of both respiration and total activity of ATP-consuming reactions on the cellular adenine nucleotide pattern was investigated in intact bovine spermatozoa. ATP consumption was manipulated by inhibition with vanadate and activation with caffeine, leading to a decrease or increase in the rate of respiration up to 70% or 20%, respectively. Oligomycin blocked the respiration to the same extent as did vanadate, suggesting that the total extramitochondrial ATP-consuming activity is vanadate-sensitive. The major part of ATP utilization must be linked to dynein ATPase, since inhibition of (Na+, K+) ATPase by ouabain showed only a small effect on respiration (-17%). Being a potent inhibitor of dynein ATPase, vanadate drastically reduced the amount of motile cells, whereas caffeine tended to increase the intensity of motion. The effects of vanadate or caffeine on respiration were paralleled by changes in cellular ATP, reflecting the response of mitochondrial respiration on the cellular ATP/ADP ratio. Respiration was found to depend on changes in the ATP/ADP ratio in the range from about 3 (+caffeine) to 9 (+vanadate). The range of response of ATP consumption to the ATP/ADP ratio was determined by varying the mitochondrial ATP production via the concentration of lactate which was used as substrate. The measured effects on both respiratory rate and ATP/ADP ratio suggested that ATP consumption was markedly dependent on ATP/ADP ratios below 5. It is concluded that lactate concentrations above 1 mM sufficiently supply bovine spermatozoa with substrate and the energy turnover is mainly limited by the activity of dynein ATPase rather than by the capacity of mitochondrial oxidative phosphorylation.
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PMID:Interdependence of mitochondrial ATP production and extramitochondrial ATP utilization in intact spermatozoa. 384 31

Comparison of beat frequencies with rates of dephosphorylation of adenosine triphosphate by glycerinated sea urchin spermatozoa as functions of adenosine triphosphate concentration suggests that each molecule of the flagellar adenosine triphosphatase, dynein, dephosphorylates one adenosine triphosphate molecule during each beat cycle.
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PMID:Adenosine triphosphate usage by flagella. 422 45

The relation between oxygen consumption and motility of Ciona spermatozoa has been measured by using pH stats to measure the acid production of spermatozoa swimming in dilute suspensions where their motility can be analyzed accurately, and calibrating the acid production by measuring it simultaneously with measurements of oxygen consumption, using more concentrated sperm suspensions. When the motility of the spermatozoa is inhibited by thiourea or by increased viscosity, their oxygen consumption decreases in proportion to the decrease in beat frequency. 80-85 % of their oxygen consumption appears to be tightly coupled to motility. The amount of movement-coupled oxidative metabolism per beat remains nearly constant, even when there are significant changes in the energy required per beat for movement against the viscous resistance of the medium. This implies that under these conditions, where the radius of curvature of flagellar bending remains constant, the amount of ATP used is determined by a stoichiometric relation to bending rather than by the energy requirement. The movement-coupled oxidative metabolism appears to be sufficient to generate approximately two molecules of ATP per beat for each molecule of the flagellar ATPase, dynein.
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PMID:Mechanochemical coupling in flagella. II. Effects of viscosity and thiourea on metabolism and motility of Ciona spermatozoa. 423 10


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