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)

Skeletal muscle fibers from muscular dystrophic mice (C57BL/10-mdx) 1-4 months of age show elevated free Ca2+ concentrations both at resting and stimulated states, although contractility of adult (2-12 months old) mouse is similar to that of normal mouse. To evaluate the sensitivity of the contractile system of adult mdx mouse muscle to elevated free Ca2+ concentration, Mg2(+)-adenosine triphosphatase (ATPase) activity was examined using myosin, myosin B, and reconstituted actomyosin. Myosin Mg2(+)-ATPase activity of the mdx mouse was significantly higher than that of the normal mouse. Myosin B ATPase activity of the mdx mouse was also higher than that of normal mouse in free Ca2+ concentrations between 10(-9) and 10(-5) M, though there was no difference in the Ca2+ concentration required for half maximal activation of ATPase activity, 2 x 10(-7) M. Polymerized actin (FA) isolated from normal and mdx mice activated rabbit myosin Mg2(+)-ATPase identically, while activation of Mg2(+)-ATPase in mdx myosin by rabbit FA was significantly lower than that in normal mouse myosin. Rapid Pi liberation by Mg2(+)-ATPase in mdx mouse myosin was about half that of normal mouse myosin, being consistent with low activation of Mg2(+)-ATPase activity by rabbit FA. Polyacrylamide gel electrophoresis in the presence of pyrophosphate showed that myosin molecules of mdx and normal mice were both composed of three isozymes, although the fast migrating myosin isozyme (M1) was decreased while the slow migrating band (M3) was increased in mdx myosin. Subunit composition of myosin analyzed by polyacrylamide gel electrophoresis in the presence of SDS showed that the content of the smallest light chain (LC3) in mdx myosin was lower than that of normal mouse myosin, which agreed with findings that mdx myosin contained less M1 isozyme than normal myosin. These results indicated that the lowered response of mdx muscle fibers to elevated Ca2+ concentration can be attributed to the isozyme composition of myosin in mdx mouse.
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PMID:Kinetic properties and isozyme composition of myosin in the mdx mutant mouse. 214 75

In this study we tested the hypothesis that reduced myofibrillar ATPase activities in end-stage heart failure are associated with a redistribution of myosin isozymes. Cardiac myofibrils were isolated from left ventricular free wall from normal human hearts and hearts at end-stage heart failure caused by coronary artery diseases, cardiomyopathy or immunological rejection. The hearts had been excised in preparation for a heart transplant. Myofibrillar Ca2(+)-dependent Mg-ATPase and myosin Ca2(+)- and K+EDTA-ATPase activities were compared. Possible changes in myosin isozyme distribution in the diseased heart were investigated using polyacrylamide gel electrophoresis of native myosin in the presence of pyrophosphate. Significant reduction in myofibrillar Ca2(+)-dependent Mg-ATPase with no changes in the sensitivity of the myofibrils to Ca2+ was observed in heart with coronary artery diseases (25.2 to 27.1% at pCa 5.83 to pCa 5.05), cardiomyopathy (21.1 to 25.5% at pCa 5.41 to pCa 5.05), and in the immunologically rejected heart (18.4 to 22.8% at pCa 5.41 to pCa 5.05). Significantly lower myosin Ca2(+)-ATPase was observed with coronary artery diseases only and myosin K-EDTA activities did not differ in diseased and normal hearts. Polyacrylamide gel electrophoresis of native myosin from the normal and three models of end-stage heart failure revealed two distinct bands in the human left ventricle and one diffuse band in the human right atria. No apparent differences in myosin isoenzyme pattern were observed between the normal and diseased hearts. Further evaluation is needed to clarify the ATPase nature of the two bands.
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PMID:Reduced cardiac myofibrillar Mg-ATPase activity without changes in myosin isozymes in patients with end-stage heart failure. 214 90

An adduct of a carbodiimide and ATP was synthesized from 1-ethyl-3-[3-(dimethylamino)propyl]carbodiimide (EDC) and the nucleotide. Despite its limited stability (t1/2 for hydrolysis of about 5 min at 25 degrees C), it was shown to react with and inactivate the calcium ATPase of sarcoplasmic reticulum in its vesicular, nonionic detergent-solubilized and purified forms. Saturation kinetics, with an ATP-EDC concentration dependence midpoint in the 10 microM range, were observed, suggesting an active-site affinity which is similar to ATP. The reaction was specific in that inactivation required reaction of about one adduct per ATPase. The modified enzyme could no longer be phosphorylated by ATP or Pi or hydrolyze p-nitrophenyl phosphate, but retained the ability to undergo the high-affinity calcium-dependent fluorescence change. It also bound trinitrophenyl-ADP and other nucleotides at least 10-fold more weakly than the unmodified ATPase. The inactivation reaction required the presence of Mg2+ and Ca2+ and was prevented by nucleotides such as ATP and ADP. For magnesium, the inactivation-enabling effect occurred with a midpoint of 3 mM. In the case of calcium, the transition resembled high-affinity binding in that it occurred cooperatively with a midpoint in the micromolar range. Higher [Mg2+] shifted this transition to higher [Ca2+]. Polyacrylamide gel electrophoresis (PAGE) demonstrated that the reaction converted the ATPase (Mr = 1.1 x 10(5)) to a species with an apparent Mr = (1.7-1.8) x 10(5). Since nonionic detergent-solubilized ATPase and purified ATPase gave similar results, intramolecular cross-linking is implicated.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Reaction of a carbodiimide adduct of ATP at the active site of sarcoplasmic reticulum calcium ATPase. 214 93

The regulation of a transmembrane ionic gradient, reflected by the cellular membrane potential, has been shown in several cell systems to be involved in the regulation of cell function. This investigation presents evidence that biologically relevant doses of ultraviolet radiation (UVR) will alter the membrane potential of keratinocytes in vitro. Estimation of the relative change in the steady-state membrane potential of the murine keratinocyte cell line PAM 212, the murine myelomonocytic cell line P388D1, and normal human keratinocytes in culture, were made through the use of the lipophilic cationic membrane potential sensitive probe; triphenylmethylphosphonium. Our observations indicate that UVR composed primarily of UVB (280-320 nm) radiation at doses as low as 100 J/m2 can induce a depolarization in the murine cell lines and a hyperpolarization in human keratinocytes. Evidence suggests that this difference in the direction of the membrane potential response reflects a difference in Na+/K+ ATPase activity following UVR. These results suggest a possible mechanism for modulation of keratinocyte activity induced by UVR.
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PMID:Ultraviolet radiation induces a change in cell membrane potential in vitro: a possible signal for ultraviolet radiation induced alteration in cell activity. 247 73

Anti-aggregatory activities in bovine aorta microsomal fractions were solubilized with Triton X-100 and separated into two fractions by DEAE-Sepharose CL-6B. One fraction strongly inhibited arachidonic acid-induced platelet aggregation, and the other inhibited ADP-induced aggregation. The latter fraction contained ADPase activity. The ADPase activity was further purified by affinity chromatography. The purified enzyme had specific activities of 43.8 and 48.2 mumol of Pi/min/mg protein for ADP and ATP, respectively. The enzyme required calcium or magnesium ions and it was insensitive to ATPase inhibitors, namely oligomycin and ouabain, and to adenylate kinase inhibitor, Ap5A. Polyacrylamide gel electrophoretic experiments indicated that only one enzyme was involved. This was confirmed by the parallel behavior of ADPase and ATPase activities throughout all the purification steps. These results suggest that the main anti-aggregatory activity of bovine aorta microsomes for ADP-induced aggregation is due to an ATP diphosphohydrolase (EC 3.6.1.5).
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PMID:Purification and partial characterization of adenosine diphosphatase activity in bovine aorta microsomes. 282 77

Plasma membranes from chick embryo neuronal primary cultures were isolated after subjecting 5-day-old cells, previously surface labeled with either lactoperoxidase-catalyzed radioiodination or galactose oxidase/NaB3H4, to a freeze-thaw cycle. The cellular material adhering to the culture substratum was washed, and the "wash" fractions were pooled and centrifuged at 37,000g. The resulting pellet was resuspended in 3 ml of buffer, layered on 33 ml of 33% sucrose, and centrifuged at 105,000g. Radioactivity was recovered at the top of the gradient. Sedimentation of these fractions and biochemical studies revealed that the pellet was 20- and 12-fold enriched in (Na+,K+)-adenosinetriphosphatase and 5'-nucleotidase, respectively. The preparation was devoid of inner mitochondrial (succinate dehydrogenase), outer mitochondrial (monoamine oxidase), endoplasmic reticulum (glucose-6-phosphatase), outer mitochondrial (monoamine oxidase), endoplasmic reticulum (glucose-6-phosphatase), and Golgi (UDP galactose:N-acetylglucosamine galactosyltransferase) enzymatic markers. Ultrastructural studies showed that the membrane preparation was homogeneous and lacked mitochondria endoplasmic reticulum and lysosomes. Polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate showed the presence of 11 protein components with molecular masses ranging from 120 to 300 kDa. This method for the isolation of plasma membranes probably depends on the capacity of the cellular material to adhere to the culture substratum and to entrap intracellular organelles during the freeze-thaw cycle. The membrane preparation seems suitable for studying the function of high-molecular-weight protein components of neuronal plasma membranes.
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PMID:Isolation of plasma membranes from neurons grown in primary culture. 282 51

Polyacrylamide gel electrophoresis (PAGE) of partially purified ATPase from vacuoles of Saccharomyces carlsbergensis under non-dissociating conditions revealed 3 bands with ATPase activity. Further PAGE in dissociating conditions showed the similarity in composition of these 3 ATPase preparations. They were assumed to contain the same vacuolar ATPase exhibiting, however, different electrophoretic mobility due to the formation of enzyme complexes with different proteins and phospholipids. The ATPase preparation with the highest electrophoretic mobility contained 6 subunits of 75, 62, 16, 14, 12 and 9 kDa. Inhibitors of vacuolar ATPase [14C]DCCD and [14C]NEM bound to a 9 kDa polypeptide, while [14C]DES associated with a polypeptide of 75 kDa. A partially purified preparation of the vacuolar ATPase was not phosphorylated by [gamma-32P]ATP under conditions when plasma membrane ATPase formed a phosphorylated intermediate. Our results show that vacuolar H+-ATPase consists of several polypeptides, does not form the phosphorylated intermediate, and evidently represents a new type of H+-ATPase of yeast.
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PMID:What family of ATPases does the vacuolar H+-ATPase belong to? 286 63

A study of the FoF1 ATPase complex of mitochondria isolated from regenerating rat liver following partial (70%) hepatectomy is presented. As we have previously reported, ATPase activity in submitochondrial particles prepared from regenerating rat liver 24 h following partial hepatectomy was depressed by 75% with respect to controls (submitochondrial particles from sham-operated animals). Polyacrylamide gel electrophoresis and immunodecoration using an antibody raised against isolated bovine heart F1 sector of the FoF1 ATPase indicated a substantial decrease in F1 content in the mitochondrial membrane from regenerating rat liver. Proton conduction by the FoF1 ATPase complex was studied by following the anaerobic relaxation of the transmembrane proton gradient (delta mu H+) generated by succinate-driven respiration. In control rat-liver submitochondrial particles containing the FoF1 moiety of the ATPase complex, anaerobic relaxation of delta mu H+ showed biphasic kinetics, whilst the same process in particles derived from regenerating rat liver exhibited monophasic kinetics and was significantly more rapid. Oligomycin and N,N-dicyclohexyl carbodiimide [(cHxN)2C] inhibited proton conductance by the F1-Fo ATPase complex in submitochondrial particles from both control and regenerating rat liver. Binding of [14C](cHxN)2C and immunodecoration using an antibody raised against bovine heart oligomycin-sensitivity-conferring protein (OSCP) indicated no difference in the content of either the (cHxN)2C binding protein or OSCP between control and regenerating rat-liver mitochondrial membranes. The results reported show that the structural and functional integrity of the Fo-F1 ATPase of rat liver is severely perturbed during regeneration.
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PMID:Studies on polypeptide composition, hydrolytic activity and proton conduction of mitochondrial FoF1 H+ ATPase in regenerating rat liver. 286 46

Membrane-bound ATPase was found in membranes of the archaebacterium Methanosarcina barkeri. The ATPase activity required divalent cations, Mg2+ or Mn2+, and maximum activity was obtained at pH 5.2. The activity was specifically stimulated by HSO3- with a shift of optimal pH to 5.8, and N,N'-dicyclohexylcarbodiimide inhibited ATP hydrolysis. The enzyme could be solubilized from membranes by incubation in 1 mM Tris-maleate buffer (pH 6.9) containing 0.5 mM EDTA. The solubilized ATPase was purified by DEAE-Sepharose and Sephacryl S-300 chromatography. The molecular weight of the purified enzyme was estimated to be 420,000 by gel filtration through Sephacryl S-300. Polyacrylamide gel electrophoresis in sodium dodecyl sulfate revealed two classes of subunit, Mr 62,000 (alpha) and 49,000 (beta) associated in the molar ratio 1:1. These results suggest that the ATPase of M. barkeri is similar to the F0F1 type ATPase found in many eubacteria.
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PMID:Characterization and purification of the membrane-bound ATPase of the archaebacterium Methanosarcina barkeri. 294 28

A novel ATPase was solubilized from membranes of an acidothermophilic archaebacterium, Sulfolobus acidocaldarius, with low ionic strength buffer containing EDTA. The enzyme was purified to homogeneity by hydrophobic chromatography and gel filtration. The molecular weight of the purified enzyme was estimated to be 360,000. Polyacrylamide gel electrophoresis of the purified enzyme in the presence of sodium dodecyl sulfate revealed that it consisted of three kinds of subunits, alpha, beta, and gamma, whose molecular weights were approximately 69,000, 54,000, and 28,000, respectively, and the most probable subunit stoichiometry was alpha 3 beta 3 gamma 1. The purified ATPase hydrolyzed ATP, GTP, ITP, and CTP but not UTP, ADP, AMP, or p-nitrophenylphosphate. The enzyme was highly heat stable and showed an optimal temperature of 85 degrees C. It showed an optimal pH of around 5, very little activity at neutral pH, and another small activity peak at pH 8.5. The ATPase activity was significantly stimulated by bisulfite and bicarbonate ions, the optimal pH remaining unchanged. The Lineweaver-Burk plot was linear, and the Km for ATP and the Vmax were estimated to be 1.6 mM and 13 mumol Pi.mg.-1.min-1, respectively, at pH 5.2 at 60 degrees C in the presence of bisulfite. The chemical modification reagent, 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole, caused inactivation of the ATPase activity although the enzyme was not inhibited by N,N'-dicyclohexylcarbodiimide, N-ethyl-maleimide, azide or vanadate. These results suggest that the ATPase purified from membranes of S. acidocaldarius resembles other archaebacterial ATPases, although a counterpart of the gamma subunit has not been found in the latter. The relationship of the S. acidocaldarius ATPase to other ion-transporting ATPases, such as F0F1 type or E1E2 type ATPases, was discussed.
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PMID:Purification and properties of the ATPase solubilized from membranes of an acidothermophilic archaebacterium, Sulfolobus acidocaldarius. 296 45


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