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)

An ATPase complex sensitive to the energy transfer inhibitors oligomycin, dicyclohexylcarbodiimide and venturicidin has been solubilized from Rhodospirillum rubrum chromatophores with Triton X-100 and further purified by centrifugation on a glycerol gradient. The partially purified RrFo . F1 contains 13 distinct polypeptide subunits, as revealed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, including the subunits of the oligomycin-sensitive, water-soluble RrF1 ATPase. The ATPase activity of RrF0 . F1 as that of the membrane-bound enzyme complex depends on Ca2+ or Mg2+ and from detailed kinetic studies it is concluded that the divalent cation-ATP complex is the substrate for both ATPase complexes. Free ATP and free Mg2+ act as competitive inhibitors, with Ki values of 1 mM and 7 muM, respectively. The subunit composition of the purified RrFo . F1 and its similarity to the membrane-bound ATPase with respect to cation dependence and sensitivity to energy transfer inhibitors suggests that it contains all the subunits of the R. rubrum coupling factor-ATPase complex.
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PMID:Coupling factor ATPase complex of Rhodospirillum rubrum. Purification and characterization of an oligomycin and N,N'-dicyclohexylcarbodiimide-sensitive (Ca+ + Mg2+)-ATPase. 15 83

Sarcoplasmic reticulum (SR) was isolated from control muscles and from muscles which had been subjected to short-term post-mortem electrical stimulation. Both preparations had similar protein compositions but the SR from electrically stimulated muscle had a lower 'extra' ATPase activity. The ability of the SR preparations from electrically stimulated muscles to accumulate Ca2+ was about the same as the controls. There was, therefore, an apparently greater efficiency of Ca2+ transport in the isolated vesicles, the reason for which is not known, but an alteration in the 'leakiness' of the membrane may be involved. Purified ATPase isolated from control and stimulated SR contained, in addition to the ATPase protein, a polypeptide of molecular weight about 30 000. The purified ATPase vesicles from electrically stimulated muscle had a reduced activity as measured by ATP splitting activity, phosphoenzyme formation from either inorganic orthophosphate (Pi) or ATP, or by an ATP in equilibrium Pi exchange reaction. These reduced activities probably result from an alteration in the binding affinities of the ATPase for ATP and Pi. The low affinity site for calcium binding was not affected by electrical stimulation. Purified ATPase vesicles from stimulated muscle were more susceptible to proteolytic attack, suggesting that the conformation of the protein or its association with the membrane lipids had been altered.
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PMID:Post-mortem electrical stimulation of muscle and its effects on sarcoplasmic reticulum adenosine triphosphatase. 15 39

Two highly purified sarcoplasmic reticulum membrane fractiones differing in their sensitivities to the uncoupling action of caffeine were isolated from white skeletal muscles of the rabbit. The main protein component of both fractions is a catalytical polypeptide of Ca2+-dependent ATPase. Treatment of the caffeine-sensitive reticular fraction by trypsin or DTNB completely removes the effect of caffeine. It was found that similar effects on the caffeine-sensitive reticular fraction are exerted by bemegride, camphor, ethymizole and cordiamine. Isolation of Ca2+-dependent ATPase from both reticular fractions and reconstruction of Ca2+-transporting vesicles were carried out. Ca2+ transport by the vesicles enriched by ATPase from the caffeine-sensitive reticular fraction is uncoupled under the effect of caffeine; however, caffeine has no effect on the vesicles enriched by caffeine-insensitive reticular ATPase. The molecular weight of caffeine-sensitive and caffeine-insensitive ATPases determined in the presence of sedium dodecyl sulfate are found to be identical. Electrophoresis in the presence of digitonin revealed different electrophoretic behaviour of the two forms of ATPase.
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PMID:[Two forms of Ca2+-dependent ATPase from sarcoplasmic reticulum]. 15 30

The effects of glucose and oxygen on the formation of the plasma membrane of Staphylococcus aureus were studied. Phospholipids were consistent components of the membrane and were not affected by glucose or oxygen. Phospholipid fatty acids in cells grown in glucose containing media were rich in Ceven (C18, C20) fatty acid chains, whereas cells grown in glucose deficient media (normal broth) had anteiso Codd (C15,C17) fatty acid chains in place of Ceven chains. This may indicate increased membrane rigidity of the cells grown in glucose containing media. Cytochromes and ATPase were present in the membrane from cells grown in normal broth, but were deficient in the cells grown in glucose containing media. Polypeptide analysis of the membrane proteins showed a deficiency of the bands corresponding to these enzymes. They were not induced by the additionof oxygen to cells grown in glucose containing media. It was concluded that glucose was the dominant factor inhibiting the formation of these membrane enzymes.
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PMID:Effect of glucose and oxygen on the structure of the plasma membrane of Staphylococcus aureus. 16 Jan 85

A high-resolution sodium dodecyl sulfate polyacrylamide gel electrophoresis system has been used to show the presence, in both whole sperm and isolated flagellar axonemes, of eight polypeptides migrating in the 300,000--350,000 molecular weight range characteristic of the heavy chains of dynein ATPase. Previously, only five such chains have been discernible. Extraction of isolated axonemes for 10 min at 4 degrees C with a solution containing 0.6 M NaCl, ph 7, releases a mixture of particles that separate, in sucrose density gradient centrifugation, into a major peak, dynein 1 ATPase, sedimenting at 21S and a minor peak at 12--14S. The polypeptide compositions of these two peaks are different. The dynein 1 peak, which contains most of the protein on the gradient, contains approximately equal quantities of two closely migrating heavy chains, with a small amount of a third, more slowly migrating chain; no other heavy chains appear in this peak. Two groups of smaller polypeptides (three intermediate chains, within the apparent molecular weight range 76,000--122,000 and four newly discovered light chains, within the apparent molecular weight range 14,000--24,000) cosediment with the 21S peak. The heavy chain composition of the 12--14S peak is more complex, all eight heavy chains occurring approximately the same ratios as occur in intact axonemes.
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PMID:Polypeptide subunits of dynein 1 from sea urchin sperm flagella. 16 91

A20668 A, B, and C are polypeptide antibiotics that inhibit phosphorylation of ADP, Mg2t-ATPase, and the ATP-driven transhydrogenase of rat liver submitochondrial particles, but not the purified F1 ATPase. In intact mitochondria, 120668 inhibits uncoupler-induced ATPase, State 3 respiration, and phosphorylation; the A and B forms are approximately equipotent with rutamycin, whereas A20668 C is less effective. Concentrations of A20668 slightly greater than required for complete inhibition of phosphoryl transfer stimulate rapid, uncoupled respiration by mitochondria under State 3 of 4 conditions. A20668 A and B are more effective uncouplers than A20668 C. In the presence of venturicidin or ossamycin, concentrations of A20668, which alone do not uncouple, stimulate oxygen consumption of mitochondria incubated under either State 3 of 4 conditions. A20668 uncoupling is not potentiated by prior inhibition of phosphoryl transfer by venturicidin X, rutamycin, aurovertin, or efrapeptin. A20668 increases mitochondrial permeability to protons in passive swelling experiments where facilitation of proton conductance correlates well with potency to uncouple. A20668 apparently binds initially at a unique locus to inhibit mitochondrial phosphoryl transfer reactions. When this site is saturated, additional antibiotic may uncouple by increasing proton conductance of mitochondria. Binding of venturicidin or ossamycin appears to interfere with the binding of A20668 to its adjacent inhibitory site, thus effectively increasing the concentration of A20668 available to uncouple.
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PMID:Uncoupling and specific inhibition of phosphoryl transfer reactions in mitochondria by antibiotic A20668. 16 81

Two fractions of gastric mucosal membranes obtained by Ficoll-sucrose density gradient centrifugation were studied by a variety of techniques to localize the polypeptides. Gel electrophoresis showed the presence of five major polypeptides and several minor ones. Only one of these, 82,000 daltons, was available for iodination in the intact tissue. The two membrane fractions differed in their accessibility to peroxidase. The denser fraction showed two major defined iodination peaks at 82,000 and 102,000 daltons. Freeze-thawing and iodinating with 131-I produced additional labeling of peaks as well as relabeling the 82,000-dalton component, showing it was accessible from both sides of the membrane. The two major components were also sensitive to cross-linking, the 102,000 polypeptide being especially sensitive to --SH oxidation. Proteolysis with trypsin removed both components in the denser membrane fraction, in addition to inhibiting the K+-ATPase and K+-p-nitrophenylphosphatase of that fraction. Phosphorylation with [gamma-32-P]ATP labeled the 102,000-dalton component and K+, HCO3- minus and p-nitrophenylphosphate reduced the level of labeling. Hence the 102,000 region contains a subunit of the ATPase, is readily iodinated in inside-out vesicles, and is the most available for interpeptide S--S cross-linking.
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PMID:Characterization of gastric mucosal membranes. VIII. The localization of peptides by iodination and phosphorylation. 16 6

1. Enzymes, proteins, glycoproteins and lipids of rodent bile were compared with those of a plasma-membrane subfraction originating from the hepatocyte bile-canalicular membrane. 2. Three bile-canalicular glycoprotein enzyme activities were detected in bile. Comparison of the pH optimum and immunoinhibition properties of membrane and bile 5'-nucleotidase activity indicated that they were the same enzyme. Correspondence between membrane and bile alkaline phosphodiesterases also suggested that they were the same enzymes. Activities of Mg2+-stimulated adenosine triphosphatase, a lipid-dependent intrinsic membrane protein, and galactosyltransferase, a Golgi membrane marker, were not detected in bile. 3. Rodent bile contained 15 polypeptide bands that differed radically from those of bile-canalicular membranes. Bands that may correspond in molecular weight to liver plasma-membrane glycoproteins were present at low staining intensities in bile. A major protein of apparent molecular weight 49 500 was present, and albumin was detected by immunodiffusion. 4. The lipid composition of bile and bile-canalicular membrane also differed. Phosphatidylcholine accounted for 82% of rat bile phospholipids, and only trace amounts of phosphatidylinositol, phosphatidylserine and sphingomyelin were present. 5. The results indicate that in healthy animals, the bile-canalicular membrane is refractory to the action of bile acids during the secretory process. The presence of only small amounts of bile-canalicular membrane components, especially glycoprotein enzymes located at the outer face of the membrane, suggests that these are released from the membrane by bile acids after secretion of bile into the canalicular spaces.
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PMID:Role of membranes in bile formation. Comparison of the composition of bile and a liver bile-canalicular plasma-membrane subfraction. 18 22

(1) The histochemical staining pattern of succinic dehydrogenase (SDH) does not show unequivocal differentiation between the type I red and type II red fibres in mammalian striated muscles. (2) Since high biochemical activity of beta-hydroxybutyric dehydrogenase (beta-HOBDH) occurs in mitochondria of the type I red fibres, the histochemical localization of this enzyme may show a pattern of staining reciprocal to that seen for myofibrillar ATPase. (3) It remains to be confirmed that the type I red fibres, which are possibly slow-twitch physiologically, possess the highest concentration of myoglobin. The histochemical correlation of myoglobin and myofibrillar ATPase in serial sections should be studied. (4) In order to achieve a more realistic picture, various glycolytic and glycogenolytic enzymes should be incubated according to the gelatin film technique, or semipermeable membrane technique or collagen polypeptide technique. A histochemical correlation of phosphorylase, LDH, PFK, alpha-glycerophosphate dehydrogenase, and myofibrillar ATPase in adjacent muscle sections may throw light on the histochemical characteristics of the different fibre-types. (5) The specific histochemical demonstration of AMPase is achieved following preincubation of tissue sections. (6) ADPase has been demonstrated by the calcium precipitation technique only (GUTH and YELLIN, 1971). A number of studies claim, however, that ADPase is not demonstrable histochemically in muscle fibres. (7) The presence of magnesium ions is a prerequisite for the adequate histochemical demonstration of mitochondrial ATPase. The latter is inhibited almost completely by 40 mM Ca++ (when Mg++ is not added) at both neutral and alkaline pH values. (8) The histochemical activity of SR-AT-Pase seen as continuous reticula but without punctuate and sub-sarcolemmal staining possibly represents the extra ATPase of SR. (9) On the basis of myofibrillar ATPase reaction, an inherent heterogeneity, between the type II red and type II white may be recognized. In addition, the above fibre-types possess their respective sub-populations. (10) Following diK+ EDTA preincubation, some type II red fibres show selective lability. These are the mitochondria-rich fibres. Thus in the total absence of both punctuate and subsarcolemmal staining, the presence of mitochondrial ATPase activity under the histochemical conditions for myofibrillar ATPase is unlikely. (11) The reaction pattern of CK/ATPase (coupled reaction) at pH 6.9 is distinctly intermyofibrillar and unlike SDH-pattern. This reticular reaction is associated mainly with the SR and hence the importance of transphosphorylation in this organelle for the Ca++ uptake and muscle relaxation. (12) The CK/ATPase reaction at pH8.0 has shown important histoenzymatic characteristics. At this pH value the type I red fibres and slow-twitch soleus show myofibrillar reaction pattern. This identical histochemical behaviour suggests that type I red fibres are possibly slow-contracting...
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PMID:Histochemical characteristics of vertebrate striated muscle: a review. 18 61

A new method has been developed for isolating synaptic junctional complexes (SJC) of high structural integrity. The major step in the isolation involves homogenization of a synaptosomal membrane (SM) fraction in a biphasic system consisting of Freon 113 and an aqueous phase containing 0.2% Triton X-100. Well-preserved SJCs, along with membrane vesicles, were recovered in the aqueous phase after low-speed centrifugation of the homogenate. The membranes were subsequently separated from the SJCs by centrifugation on a discontinuous sucrose density gradient. The purity and identity of subcellular fractions were monitored by thin sectioning electron microscopy, using specific and nonspecific staining methods. From the electron microscope studies we conclude that SJCs and their components occupy about 65% of the area covered by structures in this fraction. The assay of enzyme activities indicates that homogenization in Triton-Freon and subsequent steps of the isolation procedure affect the activities of Na, K-ATPase, cytochrome oxidase, and acid phosphatase to different extents, but do not cause total inactivation. Electrophoresis of the SJC-enriched fraction on sodium dodecyl sulfate-polyacrylamide gels has demonstrated that a polypeptide which co-migrates with tubulin is the major component in this fraction, and that a polypeptide co-migrating with actin is also present.
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PMID:Isolation of synaptic junctional complexes of high structural integrity from rat brain. 18 64


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