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)

A mutant (KF11) of Escherichia coli H+-translocating ATPase (F1-F0) has a single point mutation in the beta subunit of F1 that has lost 90% of its Mg2+-dependent ATPase activity (Kanazawa, H., Horiuchi, Y., Takagi, M., Ishino, Y., and Futai, M. (1980) J. Biochem. (Tokyo) 88, 695-703). The mutation was mapped at about the 500th nucleotide residue from the 5' end of the beta subunit gene by a genetic recombination test on the physical map of the cistron coding for the beta subunit. The mutant allele of KF11 (uncD11) was cloned on a hybrid plasmid (pKF11) via DNA isolated from a lambda uncD11 transducing phage. Restriction fragments of pKF11 containing the estimated mutation site were subjected to polyacrylamide gel electrophoresis under conditions where strands were separated into single strands. The two strands of a DNA segment, which was shown to carry an altered base, showed anomalous migration compared with those from the wild-type fragment. The results confirmed the result of mapping of the altered site by genetic tests. On the basis of these results, the nucleotide sequence of the mutated gene was determined, and a single base change of the 524th cytosine to thymine resulting in a phenylalanine for serine substitution at residue 174 of the beta subunit was found. This result, together with results on the altered properties of F1 from KF11 reported previously, indicates that residue 174 is essential for the Mg2+-dependent ATPase activity of F1 but not for the Ca2+-dependent ATPase activity.
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PMID:A phenylalanine for serine substitution in the beta subunit of Escherichia coli F1-ATPase affects dependence of its activity on divalent cations. 608 79

Membrane bound (Na,K)-ATPase partially purified from the nauplius larva of the brine shrimp, Artemia salina, was solubilized with the non-ionic detergent C12E8 in the presence of KCl. The addition of KCl was essential for protecting the enzyme against inactivation. With solubilization the enzyme could then be purified to apparent homogeneity. Electron microscopic observation of the purified enzyme revealed a homogeneous population of particles with a diameter of approximately 4 nm. The larger (alpha) subunit of the enzyme formed double bands on sodium dodecyl sulfate-polyacrylamide gels. NH2-terminal sequence analysis of the alpha subunit revealed the possible presence of two isoforms of (Na,K)-ATPase. At the third position a small but distinct amount of lysine was found in addition to glycine, suggesting that the two forms are different from each other at least at the third residue. The NH2-terminal sequence determined is as follows. NH2-Ala-Lys-Gly (Lys)-Lys-Gln-Lys-Lys-Gly-Lys-Asp-Leu-Asn-Glu-Leu-Lys-Lys-Glu-Leu-Asp-Il e-Asp -Phe-His-Lys-Ile-Pro- The sequence is abundant in hydrophilic amino acids, especially lysine, and is quite different from those of vertebrate enzymes reported so far.
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PMID:Solubilization and purification of Artemia salina (Na,K)-activated ATPase and NH2-terminal amino acid sequence of its larger subunit. 609 82

When the bovine mitochondrial F1-ATPase is inactivated with dicyclohexyl[14C]carbodiimide and then gel-filtered, from 2 to 3 g atoms of 14C are incorporated/mol of enzyme. Prior inactivation of the enzyme by the modification of an essential tyrosine residue with 4-chloro-7-nitrobenzofurazan, a reaction that can be reversed by thiols, does not affect the irreversible inactivation of the ATPase by dicyclohexyl[14C]carbodiimide. During the large scale modification of the F1-ATPase by dicyclohexyl[14C]carbodiimide which led to 70% inactivation, 1.9 g atoms of 14C were incorporated/mol of enzyme. Isolation of the alpha, beta, and gamma subunits from this large scale inactivation revealed that the gram atoms of 14C bound per mol of each of the subunits was: alpha, 0.04; beta, 0.56; and gamma, 0.04. The majority of the radioactivity in a cyanogen bromide digest of the 14C-labeled beta subunit was isolated in a fragment that has the following amino acid sequence: Glu-Leu-Ile-Asn-Asn-Val-Ala-Lys-Ala-His-Gly-Gly-Tyr-Ser-Val-Phe-Ala-Gly-Val-Gly -Glu-Arg-Thr-Arg-Glu-Gly-Asn-Asp-Leu-Tyr-Glu*-His-Met; where Glu* represents the N gamma-glutamyl derivative of dicyclohexyl[14C]urea.
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PMID:Inactivation of the bovine mitochondrial F1-ATPase with dicyclohexyl[14C]carbodiimide leads to the modification of a specific glutamic acid residue in the beta subunit. 611 57

Cytochemical techniques were used to demonstrate, with appropriate controls, alkaline phosphatase and HCO-3-activated adenosine triphosphatase (ATPase) in rat duodenal brush border microvillus membranes. Intense activity of ecto-alkaline phosphatase activity was demonstrated with 2-glycerophosphate as substrate. Although biochemical assays suggested that L-phenylalanine inhibited both alkaline phosphatase and HCO-3-activated ATPase, cytochemical studies indicated that there was marked inhibition of alkaline phosphatase revealing a specific HCO-3-activated ATPase on the inner aspect of the microvillus membrane. While it is tempting to suggest that this HCO-3-activated ATPase is implicated in active bicarbonate secretion by the duodenum, decisive identification is not yet possible.
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PMID:Cytochemical studies on the localization of alkaline phosphatase and HCO-3-activated adenosine triphosphatase in the brush border membrane of rat duodenal enterocytes. 614 Feb 47

Phosphohydrolase activity of a highly enriched commercial preparation of calf intestinal alkaline phosphatase was stimulated in the presence of HCO3. SO4, Cl, SCN, and acetate did not stimulate hydrolysis, whereas SO3 exhibited a bimodal effect, stimulating at low (25mM) concentration but inhibiting at high (100 mM) concentration. The pH optimum of this stimulation by HCO3 or SO3 was 8.5--9.0 and was maximal at a Mg concentration of 0.5 mM. HCO3 increased the Vmax of the reaction without changing the Km for ATP. ATP, GTP, UTP, and xanthosine triphosphate were equally effective as substrates, whereas AMP and p-nitrophenyl phosphate were much less effective. Alkaline phosphatase activity was inhibited by L-cysteine and L-phenylalanine, compounds that also inhibited the HCO3-ATPase activity of the preparation. Passage of the commercial preparation through an anion-exchange column yielded a fraction with enriched alkaline phosphatase and HCO3-ATPase activities; this fraction proved to be a single protein on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, on isoelectric focusing, and by immunologic techniques. These studies strongly suggest that alkaline phosphatase and anion-stimulated phosphohydrolase activities are properties of the same protein in small intestine. It is possible that alkaline phosphatase may function as a HCO3-ATPase involved in intestinal absorption and secretion.
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PMID:Anion-stimulated phosphohydrolase activity of intestinal alkaline phosphatase. 615 12

The effect of a single oral dose of endosulfan (5 mg/kg body weight) on the uptake of certain nutrients and brush-border enzymes has been studied in rat intestine. The uptake of glucose and alanine was elevated but that of leucine was decreased in endosulfan-fed rats. There was no change in the uptake of phenylalanine and lysine in insecticide-fed rats. The activities of brush-border sucrase and alkaline phosphatase were considerably increased while the activity of Na+ K+ ATPase was reduced in endosulfan-exposed animals. The leucine aminopeptidase activity was unaffected in pesticide-treated rats. There was a significant decrease in cellular LDH and GOT activities with no change in GPT activity. Neither was there a considerable increase in the cellular glucose-6-phosphatase activity (P less than 0.01) in the pesticide-fed rats. These results suggest that endosulfan toxicity induces certain functional changes in the intestine.
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PMID:Effect of a single oral dose of endosulfan on intestinal uptake of nutrients and on brush-border enzymes in rats. 618 May 24

To disclose possible regulatory mechanisms, the potential difference across the peritubular cell membrane (PDpt) and intracellular activities of sodium (Nai+), potassium (Ki+), calcium (Cai2+), bicarbonate (HCO3i-) and chloride (Cli-) have been traced continuously during inhibition of Na+/K+-ATPase with ouabain. Within 31 +/- 4 min following application of ouabain, PDpt decreases (from 57 +/- 2 mV) to half and Ki+ by 37.7 +/- 2.2 mmol/l (from 63.5 +/- 1.9 mmol/l), Nai+ increases by 35.1 +/- 4.1 mmol/l (from 13.2 +/- 2.4 mmol/l), Cai2+ by 0.17 +/- 0.2 mumol/l (from 0.09 mumol/l), HCO3i-) by 3.0 +/- 1.1 mmol/l (from 15.3 +/- 2.0 mmol/l) and Cli- by 6.2 +/- 1.0 mmol/l (from 14.4 +/- 1.6 mmol/l). Within the same time the luminal and peritubular cell membrane resistances increase 45 +/- 15% and 53 +/- 17%, respectively. The increase of the resistances is mainly due to a decrease of K+ conductance, which in turn mainly accounts for the depolarisation of PDpt. Additional experiments demonstrate that the K+ conductance of the peritubular cell membrane is sensitive to the cell membrane potential difference and possibly linked to Na+/K+-ATPase activity. The decline of PDpt probably accounts for intracellular alkalinisation which in turn reduces Na+/H+ exchange. Na+-coupled transport of glucose and phenylalanine decrease in linear proportion to PDpt. The transport of these and probably of similar substances represents the main threat to electrolyte homeostasis of the cells.
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PMID:Interaction of intracellular electrolytes and tubular transport. 622 66

Methods have been devised for isolating two of the tryptic fragments (those termed "20K" and "50K") of myosin "subfragment 1" in pure form. Fragment 20K was examined for renaturation after removal of denaturants used in its preparation. It generated a CD spectrum corresponding to ca. 64% formed structure (roughly what would be expected from its amino acid sequence) and a red-shifted UV spectrum such as arises when phenylalanine and tyrosine are perturbed by structural interactions. Actin affinity of fragment 20K was tested by 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide cross-linking, inhibition of the actin-activated ATPase of subfragment 1 containing light chain 3, cosedimentation with actin, and light scattering; the affinity exceeded 5 X 10(6) M-1. The foregoing suggests that moiety 20K has a sovereign existence in (i.e., is a domain of) myosin subfragment 1. Preliminary work indicates that fragment 50K also binds actin, but with a lesser affinity.
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PMID:Isolation and partial renaturation of proteolytic fragments of the myosin head. 623 Jun 69

Severe copper deficiency was induced in rats by rearing nursing dams and their offsprings on a semisynthetic diet comprising all the requisite nutrients and trace metals except copper. The copper-deprived rats exhibited growth retardation, severe anaemia, loss of caeruloplasmin, decrease of cytochrome oxidase, accumulation of salt-soluble collagen and a drastic decrease in iron in plasma and liver. Apart from these characteristic signs of deficiency, a marked inhibition of protein synthesis was found to occur both in vivo and in cell-free liver preparations. The curtailed ability to carry out endogenously coded amino acid incorporation into protein contrasted with the unimpaired poly(U)-acid-directed phenylalanine polymerization. This inhibition pattern, as well as the attendant disaggregation of the liver polyribosomes, suggested that the primary biosynthetic lesion was located at the stage of peptide-chain initiation. Concurrently with this alteration there was a pronounced depletion of the hepatic ATP content, associated with a parallel depression of mitochondrial respiration and an enhancement of ATPase activity. Supplementation of the copper-deficient diet with a 2-4-fold excess of iron (relative to the standard diet) prevented growth retardation and anaemia and restored normal energy metabolism, as well as unimpaired protein-synthesizing capacity. The conclusion that these disturbances were primarily determined by the secondary iron deficiency was also borne out by the finding that similar alterations occurred in rats maintained on a copper-sufficient but iron-deficient diet. On the other hand, the iron-fortified diet failed to reverse the other signs of copper deficiency, namely the loss of caeruloplasmin, the diminished rate of cytochrome oxidase and the increase of soluble collagen. The interrelations between the various biochemical lesions induced by deprivation of copper or iron are discussed and the possible role of ATP depletion in determining the derangement of protein synthesis is considered.
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PMID:Biochemical lesions in copper-deficient rats caused by secondary iron deficiency. Derangement of protein synthesis and impairment of energy metabolism. 625 58

Alteration of the surface of human neutrophils with the nonpenetrating, protein-inactivating agent p-diazobenzenesulfonic acid (DASA) was found to prevent activation of the respiratory burst by some stimuli, but not others. Production of superoxide anion (O2-) stimulated by concanavalin A or the chemotactic peptide formyl-methionyl-leucyl-phenylalanine FMLP was inhibited by DASA pretreatment, whereas O2- production stimulated by phorbol myristate acetate (PMA), sodium fluoride. or the ionophore A23187 was not inhibited by DASA. Pretreatment with DASA inhibited oxygen uptake stimulated by FMLP, but not oxygen uptake stimulated by PMA. DASA reproducibly inhibited activities of two known surface enzymes Mg++-ATPase and alkaline phosphatase, by 45-55% and 60-70%, respectively. The inhibition by DASA of O2- production did not appear to be caused by interference with binding of the affected stimuli, since pretreatment with DASA did not inhibit release of the lysosomal enzymes lysozyme and myeloperoxidase induced by concanavalin A or FMLP. Membrane-rich particulate fractions from neutrophils have been shown to contain NADPH-dependent oxidative activity that is presumably responsible for the phagocytosis-associated respiratory burst of intact cells. The PMA-activated enzyme was susceptible to inhibition of directly exposed to DASA in this particulate fraction. These findings suggest that more than one mechanism exists for activation of the respiratory burst oxidase in human neutrophils, and that the neutrophil possesses at least one oxidase that is not an ectoenzyme.
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PMID:Respiratory burst enzyme in human neutrophils. Evidence for multiple mechanisms of activation. 625 8


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