Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: HUMANGGP:009336 (ATPase)
 59,826 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The Ca2+-sensitive ATPase (adenosine triphosphatase) of human erythrocyte membranes is activated, not only by Ca2+ ions, but also by a series of other bivalent metal ions including Sr2+, Ba2+, Mn2+, Ni2+, Co2+, Cd2+, Cu2+, Zn2+ and Pb2+. The degree of activation is dependent on the radius of the ion rather than on its nature, in contrast with the dissociation constant of the enzyme--metal ion complex.
 ...
PMID:Activation of membrane-bound high-affinity calcium ion-sensitive adenosine triphosphatase of human erythrocytes by bivalent metal ions. 12 84

In immature rats the temperature dependence of Na+-K+ ATPase of a crude homogenate of brain shows a compex curve with two activity maxima. When EDTA was present in the homogenization medium the curve obtained was of simpler, curvilinear type showing an increased activity at temperatures above 20 degrees C. The Na+-K+ ATPase activity in similar preparation from adult brain were not complex but curvilinear whether EDTA was used or not; however, EDTA increased the activity at temperatures above 20 degrees C. When such chelating agents as EDTA or histidine were used in preparation of microsomes from immature rat brain, the temperature dependence curve of Na+-K+ ATPase in this membrane fraction was changed to a steeper and simpler curve with increased activity especially at temperatures above 20 degrees. These agents, however, did not eliminate totally the complex shape of curve found in microsomes prepared without the presence of any chelating agents. When microsomes were prepared by using NaI-technique the temperature dependence of this enzyme was linear between temperatures 15-14 degrees, the activity being 4-5-fold higher than in the ordinary microsomal preparation. A stimulation of the Mg2+ ATPase by Na+ ions (100mM) was found at temperatures below 30 degrees but an inhibition by the same concentration of Na+ at upper temperatures. This effect together with the lowered activity due to bivalent metal ions (e.g. Ca2+, Cu2+) in 'crude' preparations was thought to be reasons for the complex shape of temperature dependence curve of Na+-K+ ATPase activity.
 ...
PMID:Temperature dependence of brain ATPases in immature and adult rats. 12 4

Rat spermatozoa from the cauda epididymidis were found to have a lower activity of the surface ATPase than the spermatozoa from the caput region. The enzyme from spermatozoa of both regions had the same Michaelis constant (Km) for ATP of 5 X 10(-4) M. It was partly inhibited by ouabain and fluoride, but strongly inhibited by Cu2+, Zn2+,p-chloromercuribenzoate, 8-anilino-1-naphthalenesulphonate Triton X-100, Lubrol-PX, urea, guanidine hydrochloride, sodium dodecyl sulphate and glycerylphosphorylcholine. The enzyme of the spermatozoa from the cauda epididymidis was more sensitive to inhibition by ouabain and fluoride but less sensitive to inhibition by Cu2+ than that of the cells form the caput region. The Arrhenius plot of the temperature dependence of enzymatic activity varied for the cells from the caput and cauda epididymidis. The differences in the enzyme properties of spermatozoa from the two regions of the epididymis suggested that the decline in the activity during epididymal maturation may reflect changes in the lipids and sulphydryl groups of the sperm membrane.
 ...
PMID:Changes in surface ATPase of rat spermatozoa in transit from the caput to the cauda epididymidis. 13 82

The isolated nuclei of wheat embryo possess the ATPase activity. The addition of Mg2+ and Ca2+ significantly increases the activities of nuclear ATPases, whereas Hg2+, Cu2+ and Mn2+ inhibit the activity. The activating effect of Mg2+ is enhanced by an addition of Na and K ions. The activity of wheat embryo nuclear Mg-ATPase is higher than its Ca-ATPase activity; both ATPases also differ in their pH optima. Separation of total nuclear protein according to the solubility of its individual protein components in wheat and strong salt solutions, using the detergents, as well as ammonium sulfate precipitation and dialysis do not result in separation of Mg-activated and Ca-activated ATPases, although their levels of activities and ratios change in the course of fractionation. The Mg- and Ca-ATPase activities of the wheat embryo nuclei were found in the nuclear fraction of albumin, in nonhistone proteins and nuclear membranes. In the albumin nuclear fraction and subfractions of non-histone proteins the higher level of activity is observed in Ca-ATPase, whereas in the nuclei and soluble fractions of residual proteins in Mg-ATPase.
 ...
PMID:[Properties and localization of Mg- and Ca-ATpase activities in wheat embryo cell nuclei]. 14 25

The proteins of sarcoplasmic reticulum were cross-linked by rapid oxidation of thiol groups with I2. About two-thirds of the thiols were oxidized without any significant cross-linking, implying an extensive formation of intramolecular disulphide bonds. When the thiols were completely oxidized at room temperature a series of oligomers containing up to five molecules were observed, as well as large aggregates which were excluded from the gels. Complete oxidation at -10 degrees C left most of the ATPase (adenosine triphosphatase) as monomer. Similar results were obtained when copper-phenanthroline complexes or dimethyl suberimidate were used as cross-linking reagents. We conclude that most of the cross-linked species arise by linking of randomly colliding ATPase molecules which are present in the membrane at very high concentration.
 ...
PMID:Cross-linking experiments with the adenosine triphosphatase of sarcoplasmic reticulum. 15 36

Tightly bound magnesium was found in soluble, purified ATPase (F1) from beef heart mitochondria in the amount of 1 mol/mol of F1. Iron, zinc, cobalt, manganese, calcium, sodium, copper, and potassium were not tightly bound at stoichiometric levels. Removal of magnesium by chelating agents caused loss of ATPase activity. Removal of tightly bound nucleotide by gel filtration in 50% glycerol- or 60 mM K2SO4-containing buffers did not remove magnesium. Cold dissociation did release magnesium when complete denaturation was accomplished. The results suggest that magnesium is an integral part of F1, that it is required for activity, and that magnesium and nucleotides are tightly bound at separate sites. The idea that the tightly bound nucleotides are not complexed with cations suggests certain structural requirements at their binding sites which might account for the unusual properties of the sites.
 ...
PMID:Tightly bound magnesium in mitochondrial adenosine triphosphatase from beef heart. 15 99

It was found in experiments on male albino rats that hypophysectomy was accompanied by an increase of potassium (on account of its accumulation in the mitochondria, nuclei and the microsomes) and copper in the liver. At the same time there was an increase in this organ of tha activity of Mg-2+-Na-+-K-+-ATPase and Mg-+-ATPase, and also a rise of ceruloplasmin activity in the blood serum. STH and TTH restored the sodium content to the normal and increased potassium level in the liver of hypophysectomized rats. ACTH and STH increased copper content in the hepatic tissue and normalized the activity of ceruloplasmin in the blood. All the hormones used promoted normalization of ATP-ase activity.
 ...
PMID:[The effect of STH, TTH and ACTH on several aspects of copper, sodium and potassium metabolism in the livers of hypophysectomized white rats]. 16 74

Effect of cuprizone has been studied on some biochemical properties of megamitochondria obtained from the mouse liver. (1) Contents of Ca2+, Mg2+ and Cu2+ in the blood or the liver homogenates were not altered by cuprizone intoxication, whereas those in liver mitochondria were significantly altered: after 3-4 days' intoxication, content of Ca2+ was decreased and was remarkably increased after 14-15 days' intoxication. Content of Mg2+ behaved contrarily. (2) Both cytochrome oxidase and ATPase activities were unchanged in the liver megamitochondria, but monoamine oxidase (MAO) activity was significantly decreased. Value of I50 (50% inhibition) for MAO was determined to be 0.33 mM using the control liver mitochondria. Cuprizone had almost no effect on MAO activity of kidney or heart mitochondria both in vivo and in vitro. (3) The amount of lysolecithin was increased in the liver megamitochondria. These results were discussed in the light of membrane fusion phenomenon which plays a key role in the mechanism of megamitochondrial formation.
 ...
PMID:Mechanism of the formation of megamitochondria by copper-chelating agents. V. Further studies on isolated megamitochondria. 20 65

When (Na+ + K+)-ATPase is reacted with Cu2+ or Cu2+-phenanthroline, cross-linking of the two subunits (alpha and beta) occurs. The major products are alpha,beta- and alpha,alpha-dimers. The alpha,beta-dimer is unstable in the presence of EDTA, but becomes stable when it is first exposed to digitonin or Triton X-100. Conversion of alpha-CU2+-beta to alpha-S-S-beta is suggested. If the enzyme that is pretreated with these detergents is used, only the stable alpha,beta-dimer is obtained, and the formation of alpha,alpha-dimer is inhibited. The data are consistent with alpha 2 beta 2 quaternary structure of the enzyme.
 ...
PMID:(Na+ + K+)-ATPase: effects of detergents on the cross-linking of subunits in the presence of Cu2+ and o-phenanthroline. 22 65

Detailed studies of hepatic metabolism of lipemic BHE and nonlipemic Wistar rats were conducted. Hepatic lipogenic capacity was varied through the use of starvation or meal feeding. Livers were clamped in precooled copper plates and used for the assay of glycolytic, gluconeogenic, and lipogenic metabolites. Redox and phosphorylation states were calculated. Mitochondrial metabolism was evaluated through studies of the oxygen consumption of isolated mitochondria and through the study of the activities of the alpha-glycerophosphate and malate aspartate shuttles and ATPase. BHE rats have higher phosphorylation states, higher redox ratios, and lower shuttle activities and oxygen consumption by isolated mitochondria than their Wistar cohorts. The differences in oxidative phosphorylation, redox and phosphorylation states, and in the various shuttle activities suggest that BHE liver cells are geared towards lipogenesis at the expense of oxidative phosphorylation. It appears that the activity of the shuttles is controlled in part by phosphorylation state which in turn appears to affect respiration. We theorize from these data that genetically determined differences in the structure and function of the mitochondrial membrane (and perhaps the cell membrane as well) may affect the communication (via metabolites and adenine nucleotides) between the cytosol and mitochondria. Subtle differences in the exchange of metabolites and/or adenine nucleotides across the mitochondrial membrane could thus explain the lipogenic tendency of the liver of the BHE rat and the subsequent development of maturity onset hyperlipemia and hyperglycemia in this strain of rat.
 ...
PMID:Studies on the control of lipogenesis: strain differences in hepatic metabolism. 43 Feb 26


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