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

---

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

Highly purified preparations of Streptococcus faecalis ATPase contain a similar but inactive protein detected by prolonged polyacrylamide gel electrophoresis. The inactive protein appears to arise by proteolytic cleavage of the major subunits in the enzyme. By use of a new technique, subunit analysis in SDS gels was performed on the enzyme band and the inactive protein band excised from a polyacrylamide gel after electrophoresis. The results indicated that the ATPase has the composition alpha3beta3gamma in which alpha = 60,000, beta = 55,000, and gamma = 37,000 daltons. The inactive protein appears to have the composition (f)6 in which f = 49,000 daltons. There is also evidence that the enzyme band contains some slightly modified forms of the ATPase, such as alpha3beta2 (f)gamma. The inactive protein lacks the capacity for tight nucleotide binding. Our experiments show that the tight ATPase-nucleotide complex formed in S. faecalis cells (the endogenous complex) behaves differently from the tight complex formed in vitro (the exogenous complex). We prepared a doubly labeled complex containing endogenous 32P-labeled ADP and ATP and exogenous 3H-labeled ADP. We observed that the addition of free nucelotide to the doubly labeled ATPase displaced the exogenous bound ligand from the enzyme but not the endogenous bound nucleotide. We suggest that the displaceable and nondisplaceable forms of the tight ATPase-nucleotide complex correspond to two different conformational states of the enzyme.
...
PMID:Studies of substructure and tightly bound nucleotide in bacterial membrane ATPase. 12 88

Basal and trypsin-stimulated adenosine triphosphatase activities of Escherichia coli K 12 have been characterized at pH 7.5 in the membrane-bound state and in a soluble form of the enzyme. The saturation curve for Mg2+/ATP = 1/2 was hyperbolic with the membrane-bound enzyme and sigmoidal with the soluble enzyme. Trypsin did not modify the shape of the curves. The kinetic parameters were for the membrane-bound ATPase: apparent Km = 2.5 mM, Vmax (minus trypsin) = 1.6 mumol-min-1-mg protein-1, Vmax (plus trypsin) = 2.44 mumol-min-1-mg protein-1; for the soluble ATPase: [S0.5] = 1.2 mM, Vmax (-trypsin) = 4 mumol-min-1-mg protein-1; Vmax (+ trypsin) = 6.6 mumol-min-1-mg protein-1. Hill plot analysis showed a single slope for the membrane-bound ATPase (n = 0.92) but two slopes were obtained for the soluble enzyme (n = 0.98 and 1.87). It may suggest the existence of an initial positive cooperativity at low substrate concentrations followed by a lack of cooperativity at high ATP concentrations. Excess of free ATP and Mg2+ inhibited the ATPase but excess of Mg/ATP (1/2) did not. Saturation for ATP at constant Mg2+ concentration (4 mM) showed two sites (groups) with different Kms: at low ATP the values were 0.38 and 1.4 mM for the membrane-bound and soluble enzyme; at high ATP concentrations they were 17 and 20 mM, respectively. Mg2+ saturation at constant ATP (8 mM) revealed michealian kinetics for the membrane-bound ATPase and sigmoid one for the protein in soluble state. When the ATPase was assayed in presence of trypsin we obtained higher Km values for Mg2+. These results might suggest that trypsin stimulates E. coli ATPase by acting on some site(s) involved in Mg2+ binding. Adenosine diphosphate and inorganic phosphate (Pi) act as competitive inhibitors of Escherichia coli ATPase. The Ki values for Pi were 1.6 +/- 0.1 mM for the membrane-bound ATPase and 1.3 +/- 0.1 mM for the enzyme in soluble form, the Ki values for ADP being 1.7 mM and 0.75 mM for the membrane-bound and soluble ATPase, respectively. Hill plots of the activity of the soluble enzyme in presence of ADP showed that ADP decreased the interaction coefficient at ATP concentrations below its Km value. Trypsin did not modify the mechanism of inhibition or the inhibition constants. Dicyclohexylcarbodiimide (0.4 mM) inhibited the membrane-bound enzyme by 60-70% but concentrations 100 times higher did not affect the residual activity nor the soluble ATPase. This inhibition was independent of trypsin. Sodium azide (20 muM) inhibited both states of E. coli ATPase by 50%. Concentrations 25-fold higher were required for complete inhibition. Ouabain, atebrin and oligomycin did not affect the bacterial ATPase.
...
PMID:Membrane bound and soluble adenosine triphosphatase of Escherichia coli K 12. Kinetic properties of the basal and trypsin-stimulated activities. 12 30

Solution of thrombosthenin, the contractile protein complex isolated from pig platelets, have been studied by analytical ultracentrifugation and zone sedimentation in sucrose density gradients. Freshly prepared thrombosthenin in 0.6 M KCl shows a prominent peak in the ultracentrifuge with S degrees 20w about 5.5 and higher molecular weight aggregates (greater than 100S) sedimenting quickly to the bottom of the cell. Short term storage of high ionic strength solutions of thrombosthenin induces actomyosin-like gel formation and these gels dissociate with ATP and Mg2+ ions into two components of S degrees 20w 8.0 and S degrees 20w50. The supernatant, after actomyosin gel removal, contains only the S degrees 20w5.5 protein. From results of Ca2+ ATPase activity measurements and SDS polyacrylamide gel electrophoretic mobilities of dissociated thrombosthenin separated into fractions in sucrose density gradients, it is concluded that the S degrees20w5.5 protein species is the myosin-like protein of thrombosthenin. The S degrees 20w8.0 protein is not fibrinogen but also has myosin-like properties and is believed to be myosin dimer. Species of higher S values seen in the presence of ATP and Mg2+ in the analytical ultracentrifuge and located in the higher density zones of the sucrose gradients all gave in SDS polyacrylamide gel electrophoresis a single band of molecular weight 46-47,000 daltons. These subunit proteins appear to be derived from a range of polymeric variants of the F-actin-like protein of the contractile complex. All these higher density F-actin-like proteins readily form superprecipitates and display syneresis when combined with rabbit skeletal muscle myosin or platelet myosin. They are also all capable of conferring upon these two myosins a Mg2+ activated ATPase activity. It is suggested that in thrombosthenin solutions a myosin monomer-dimer equilibrium state exists which can be directionally influenced by a number of factors. The coexistence in the solution of F-actin and Mg2+ ATP, for example, increases the propensity of the myosin-like protein to form the higher molecular weight aggregate. Such aggregation may be the initiating mechanism for the intracellular organization of the thick filaments of the actomyosin complex, preparatory to a contractile event.
...
PMID:Platelet contractile proteins: separation and characterization of the actin and myosin-like components. 12 96

Sodium dodecyl sulfate polyacrylamide gel electrophoresis reveals in the rabbit skeletal muscle sarcolemma the presence of four major protein bands corresponding to molecular weight 216,000, 110,000, 44,000, 15,000, and smaller amounts of 148,000, 78,000, 68,000, 37,000, 27,000 proteins. (Na+-K+)-ATPase isolated from rabbit skeletal muscle contains 102,000, 44,000, and 32,000 protein bands. Sarcolemma is resistant to the solubilizing effect of Triton X-100, Lubrol, and deoxycholate. Sarcolemmal proteins, especially sodium-potassium-ATPase, are sensitive to digestion with trypsin.
...
PMID:Characterization of sarcolemma from rabbit skeletal muscle. 13 Jun 57

The subunit composition, the thiol group content and the biological activities of cardiac tropomyosins (TM) of various animal species were compared. Cardiac TM from small animals such as rabbit, guinea-pig, rat and dog contain 2 SH/mole and were resolved into one band on SDS and acid urea electrophoresis and into two bands on alkaline urea electrophoresis. Chicken cardiac TM likewise gave one band and it contains 4 SH/mole. In contrast pig, sheep and human cardiac TM contain respectively 2.6, 2.4, and 2.4 SH/mole and were resolved into two bands alpha and beta on the different electrophoresis systems used, with a beta:alpha ratio respectively of I:4.2, I:4.6, I:4.8. The alpha-TM components from sheep skeletal and pig and sheep cardiac muscles were more positively charged than the rabbit skeletal alpha-TM component, as shown in alkaline urea electrophoresis system. The alphaalpha and alphabeta combinations of dimers found for skeletal muscle by other authors, were also found for cardiac pig TM. All the TM have the same effect on the Ca2+-stimulated ATPase activity of desensitized actomyosin (DAM) and on the Mg2+-stimulated ATPase activity of DAM with troponin-complex. This work suggests that the subunits of the TM from skeletal and cardiac muscles are heterogenous in their M.W. and their charges and that in the heart as well as in skeletal muscle a relationship seems to exist between the amount of the beta component and the speed of contraction of the muscle: a higher amount of this component was found in the bulky hearts which are also those which contract slower.
...
PMID:A comparative study of skeletal and cardiac tropomyosins: subunits, thiol group content and biological activities. 13 Dec 98

The relaxing protein (TM-TN complex) was isolated from plasmodia of Physarum. SDS-gel electrophoresis revealed that the relaxing protein consists of tropomyosin subunits with a molecular weight of 35,000 troponin subunits with molecular weights of 38,000 (T) and 24,000 (I) and several other components. No component corresponding to muscle troponinC (MW-18,000) was detected in the plasmodium relaxing protein. The relaxing protein combined with muscle F-actin, and inhibited the ATPase [EC 3.6.1.3] activity and superprecipitation of reconstituted muscle actomysin in the absence of Ca2+ ions. The inhibition was reversed by adding 1 muM Ca2+ ions.
...
PMID:Physarum tropomyosin-troponin complex. Isolation and properties. 13 91

The relationship between bile salt-independent canalicular flow and ATPase activity in liver plasma membranes (LPM) enriched in bile canaliculi, was studied in control, hyperthyroid, and hypothyroid rats. Canalicular bile production was significantly increased in hyperthyroid rats (3.19 +/- 0.23 mul/min per g liver) compared to controls (2.27 +/- 0.24 mul/min per g liver), while it diminished in hypothyroid animals (1.58 +/- 0.17 mul/min per g liver). Although bile salt excretion was also increased in hyperthyroid animals (62.4 +/- 13.3 vs. 41.2 +/- 8.4 nmol/min per g liver), the stimulation in canalicular secretion was primarily related to enhancement of the bile salt-independent fraction of flow (2.47 mul/min per g liver in hyperthyroid rats vs. 1.67 mul/min per g liver in controls). LPM Na+, K+-ATPase activity doubled in hyperthyroid animals (21.5 +/- 5.8 vs. 10.7 +/- 3.1 mumol Pi/mg protein per h) while Mg++-ATPase activity remained unchanged and 5'-nucleotidase activity increased to a small but significant extent. In hypothyroid rats, bile salt excretion remained unchanged from control values so that the reduced secretion was entirely secondary to an inhibition of bile salt-independent secretion (1.19 mul/min per g liver). Na+, K+-ATPase activity in the LPMs from hypothyroid animals decreased by nearly 50% (5.4 +/- 1.6 mumol Pi/mg protein per h), although comparable reductions in the specific activity of Mg++-ATPase and 5'-nucleotidase were also observed. Administration of L-thyroxine to hypothyroid animals restored both bile salt-independent canalicular secretion and membrane enzymes to control values within 2 and 4 days, respectively. Sodium dodecyl sulfate gel electrophoresis demonstrated no significant changes in LPM protein fractions from any of the treatment groups. These studies indicate that thyroid hormone has a parallel effect on bile salt-independent canalicular secretion and LPM Na+, K+-ATPase activity, supporting the hypothesis that Na+ transport and Na+, K+-ATPase may be determinants of bile salt-independent canalicular flow.
...
PMID:The effect of thyroid hormone on bile salt-independent bile flow and Na+, K+ -ATPase activity in liver plasma membranes enriched in bile canaliculi. 13 19

The ATPase activity of actomyosin prepared from taenia coli muscle of guinea pig was found to increase upon adding rabbit skeletal heavy meromyosin (HMM) in the absence of Ca2+. SDS-gel electrophoresis of muscle homogenates did not reveal the presence of troponin. Ca2+-regulation in taenia coli muscle thus appears to be myosin-linked. The glycerinated muscles which did not develop any tension in the presence of EGTA contracted after irrigation with rabbit skeletal myosin. Skeletal HMM could also cause tension generation in strips of glycerinated taenia coli in the presence of EGTA. The tension developed by the muscles in the presence of Ca2+ was increased if HMM was added. The HMM-induced tension was associated with a marked increase in ATPase activity both in the presence and in the absence of Ca2+. No HMM-associated tension could be detected when inactivated HMM was employed or when MgATP was substituted with Mg-pyrophosphate or Mg-AMP-PNP. The mechanical effect of HMM probably results from a mechanochemical interaction between the added HMM and muscle actin.
...
PMID:Evidence for myosin-linked regulation in guinea pig taenia coli muscle. 13 41

The present studies concern the roles of synthesis and degradation of the large subunit of (Na+ + k+)-adenosine triphosphatase (NaK-ATPase) in the response to triiodothyronin (T3). Single doses of either the diluent of T3 (50 mug/100 g body weight) were given to two pairs of surgically thyroidectomized rats. Twenty hours after injection, the rats received 3H- or 35S-labeled methionine administered as a constant injusion into the tail vein for 1 h. The kidneys were removed either 8 h or 20 h after infusion and the eight kidneys were divided into pairs, as follows. I, 3H (diluent)/35S (T3); II, 35S (diluent)/3H (T3); III, 3H (diluent)/35S (diluent); IV, 3H (T3)/35S (T3). Partially purified NaK-ATPase was prepared from the pooled homogenates and prepared from the pooled homogenates and analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAG-electrophoresis). The large subunit of NaK-ATPase was identified by (Na+ + mg2+)-dependent and K+-sensitive incorpotation of 32P from [gamma-32P]ATP. This component had an estimated molecular weight of 92,000 and migrated as a single peptide in gels of varying total carylamide concentration, with respect to: (1) Coomassie blue staining, (b) (Na+ + Mg2+)-dependent, K+-sensitive incorporation of 32P from [gamma-32-P]ATP, and (c) T3-dependent enhanced incorporation of labeled methionine. T3 augmented incorporation of labeled methionine into the large subunit by 44% 8 h after infusion of the amino acid and by 61% 20 h after infusion. Incorporation of methionine into two adjacent polypeptides in the SDS gels was unaffected by thyroid status. The effect otical NaK-ATPase was assessed by a double label technique. Pairs of thyroidectomized rats were injected with either the diluent or 50 mug of T3/100 g body weight at 48-h after the first injection (diluent or T3, i.e. Day "zero"). Kidney cortices were processed on either Day 4 or Day 6; the partially purified NaK-ATPase fraction was prepared, labeled with [gamma-32P]ATP, and analyzed by SDS-PAG-electrophoresis. The degredation rate constants of the large subunit were similar; 0.145 and 0.124 day-1 for the hypothyroid and T3-treated groups, respectively. Thus, the T2-dependent increase in incorporation of labeled methionine into the large subunit appears to result from enhanced synthesis and this increase is sufficient to account for the entire increase in both the number of the activity of the NaK-ATPase units.
...
PMID:Effect of triiodothyronine on the synthesis and degradation of renal cortical (Na+ + k+)-adenosine triphosphatase. 13 43

1. Digitonin treated membrane preparations purified from dog kidney lose their (Na+,K+)-ATPase (ATP phosphohydrolase, EC 3.6.1.3) activity, but the K+-phosphatase and Na+-dependent ADP-ATP exchange activities survive and remain ouabain-sensitive. Because the enzyme preparations consist largely of pure (Na+,K+)-ATPase, these effects of digitonin must be intrinsic to the Na+ pump. 2. Concomitant with these enzymatic changes, digitonin treatment alters the sensitivity of the phosphatase and exchange activities to ouabain. 3. Attempts to measure ouabain binding by the usual centrifugation or filtration methods proved unsuccessful. A filtration method involving a double 0.01 mum filter and omitting water washes is necessary to demonstrate ouabain binding. Under these conditions, ouabain binding capacity appears to be unchanged in the presence of digitonin, but the apparent dissociation constant is doubled. 4. Ouabain binding is rendered more reversible by digitonin treatment, since washing filters with water removes a large fraction of bound ouabain without affecting the retention of exchange activity. 5. The double filter method traps essentially all of the ADP-ATP exchange activity on the filter. However, a large and somewhat variable proportion of the K+-phosphatase activity passes through the filter. Sodium dodecyl sulfate polyacrylamide gel analysis of the filtrate shows that a small amount of filtrable protein catalyzed this phosphatase activity at greatly increased turnover rates. Both subunits of the (Na+, K+)-ATPase are present in this latter protein fraction.
...
PMID:The measurement of ouabain binding and some related properties of digitonin-treated (Na+,K+)-ATPase. 13 44


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

---