On the Mechanism of Na+- and K+-Stimulated Hydrolysis of Adenosine Triphosphate

Schoner, Wilhelm; Ilberg, C. von; Kramer, Ruth M.; Seubert, W.

doi:10.1007/978-3-662-25813-2_45

Cited by 104 publications

(37 citation statements)

References 25 publications

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“…The quantification of the enzyme has been described earlier [32] like the binding of [c~-~'P]C~ATP and the phosphorylation of the enzyme with [y-32P]CrATP [I]. Protein was determined according to Lowry et al [33].…”

Section: Enzyme and Assaysmentioning

confidence: 99%

Chromium(III)ATP inactivating (Na⁺+ K⁺)‐ATPase supports Na⁺‐Na⁺ and Rb⁺‐Rb⁺ exchanges in everted red blood cells but not Na⁺,K⁺ transport

Pauls

Serpersu

Kirch

et al. 1986

European Journal of Biochemistry

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1. The chromium(II1) complex of ATP, an MgATP complex analogue, inactivates (Na' + K+)-ATPase by forming a stable chromo-phosphointermediate. The rate constant k2 of inactivation at 37 OC of the &y-bidentate of CrATP is enhanced by Na' = 15 mM) and Mg2+ = 0.7 mM). These cations did not affect the dissociation constant of the enzyme-chromium-ATP complex.2. The inactive chromophosphoenzyme is reactivated slowly by high concentrations of Na+ at 37°C. The half-maximal effect on the reactivation was reached at 40 mM NaCl, when the maximally observable reactivation was studied. However, 126 mM NaCl was necessary to see the half-maximal effect on the apparent reactivation velocity constant. K + ions hindered the reactivation with a Ki of 70 pM.3. Formation of the chromophosphoenzyme led to a reduction of the Rb' binding sites and of the capacity to occlude Rb'. 4.The lJ,y-bidentate of chromium(II1)ATP (Kd = 8 pM) had a higher affinity than the a,lJ,y-tridentate of chromium(II1)ATP (Kd = 44 pM) or the cobalt tetramine complex of ATP (Kd = 500 pM). The P,y-bidentate of the chromium(II1) complex of adenosine 5'-[PJ-methyleneltriphosphate also inactivated (Na' + K+)ATPase. 5.Although CrATP could not support Na+,K+ exchange in everted vesicles prepared from human red blood cells, it supported the Na+-Na+ and Rb+-Rb+ exchange.6. It is concluded that CrATP opens up Na' and K + channels by forming a relatively stable modified enzymeCrATP complex. This stable complex is also formed in the presence of the chromium complex of adenosine 5'-[B,y-methyleneltriphosphate. Because the P,y-bidentate of chromium ATP is recognized better than the a,lJ,ytridentate, it is concluded that the triphosphate site recognizes MgATP with a straight polyphosphate chain and that the Mg2' resides between the P-and the y-phosphorus. The enhancement of inactivation by Mg2+ and Na' may be caused by conformational changes at the triphosphate site.Incubation of (Na' + K+)-ATPase with the MgATP complex analogue chromium(II1)ATP leads to the inactivation of the enzyme by the formation of a stable phosphointermediate [l]. This inhibition occurs in the absence of Na+ and Mg", which otherwise are absolutely necessary to build up the two differently reactive forms of phosphointermediate from ATP [2 -51. Such two forms of phosphointermediate, which are passed through during active Na+ and K + transport [2 -51, have also been found to exist during the active Ca2 + transport catalyzed by the CaZ +-ATPase of sarcoplasmic reticulum [6]. When the latter enzyme is incubated with CrATP, Ca2+ is occluded in a stable form and the enzyme is phosphorylated and inactivated [7]. Since occlusion of Na'and Rb' ions in (Na' + K+)-ATPase has been reported [3, 8,9], it seemed possible that Na' ions might also be occluded in the CrATP-inactivated enzyme in a more stable way. Using the relatively stable MgATP complex analogue CrATP, it should also be possible to resolve some of the uncertainties concerning the functions of Mg2 + and MgATP in the catalytic and ion transport process: ...

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Section: Enzyme and Assaysmentioning

confidence: 99%

Chromium(III)ATP inactivating (Na⁺+ K⁺)‐ATPase supports Na⁺‐Na⁺ and Rb⁺‐Rb⁺ exchanges in everted red blood cells but not Na⁺,K⁺ transport

Pauls

Serpersu

Kirch

et al. 1986

European Journal of Biochemistry

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“…(Nu' + K+)-activated ATPase from beef brain was prepared as described previously [24]. The enzymatic activity was measured with the coupled optical assay [24].…”

Section: Enzyme and Assaysmentioning

confidence: 99%

“…The enzymatic activity was measured with the coupled optical assay [24]. The reaction was continuously recorded and corrected for a Mg2+-activated ATPase by inhibition of (Na' + K+)-activated ATPase with 0.1 mM ouabain.…”

Section: Enzyme and Assaysmentioning

confidence: 99%

“…Na+-dependent phosphorylation and deterand the ATP analogues indicated in the legends of the figures. Inactivation of (Na' + K+)-ATPase was followed by transferring a 0.03-ml aliquot of the reaction medium to the coupled optical assay [24].…”

Section: -No Nbs2mentioning

confidence: 99%

“…Na+ ions increase ouabain binding only under those conditions in which a phosphorylated intermediate is formed [35,36]. The lower level of followed with the coupled optical assay [24]. The assays contained instead of ATP in (A) 2 mM sITP; (B) 1 mM clITP Table 1.…”

Section: Studies With 55'dithio-bis(2-nitrobenzoate)mentioning

confidence: 99%

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Evidences for a Sulfhydryl Group in the ATP-Binding Site of (Na+ + K+)-Activated ATPase

et al. 1975

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5,5'-Dithio-bis(2-nitrobenzoate) inhibited (Na' + K+)-activated ATPase by affecting the Nafdependent phosphorylation reaction. ATP and ADP but not ITP protected the enzyme at low concentrations against the inactivation.The ATP analogues 6-mercaptopurine riboside-5'-triphosphate and S-(2,4-dinitrophenyl)-6-mercaptopurine riboside-5'-triphosphate inactivated (Na+ + K+)-ATPase whereas the respective monophosphates left the enzyme unaffected. S-(2,4-Dinitrophenyl)-6-mercaptopurine triphosphate inactivated the partial reactions of (Na+ + K +)-ATPase, i.e. the ADP-binding capacity and the Na+-dependent phosphorylation reaction in parallel with the overall enzymatic activity. ATP protected against the inactivation of (Naf + K+)-ATPase by S-(2,4-dinitrophenyl)-6-mercaptopurine triphosphate. Dithiothreitol hindered the inactivation of (Na' + K+)-ATPase by S-(2,4-dinitrophenyl)-6-mercaptopurine riboside-5'-triphosphate and 6-mercaptopurine riboside-5'-triphosphate. Treatment with dithiothreitol restored the activity of (Na' + K+)-ATPase which had been inactivated by 6-mercaptopurine riboside-5'-triphosphate but it did not restore the activity of that enzyme which was pretreated with S-(2,4-dinitrophenyl)-6-mercaptopurine riboside-5'-triphosphate.

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Primary Active Transport of Provastatin Across the Liver Canalicular Membrane in Normal and Mutant Eisai Hyperbilirubinaemic Rats

Yamazaki

Kobayashi

Sugiyama

1996

Biopharm. Drug Dispos.

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We have previously demonstrated that the HMG‐CoA reductase inhibitor pravastatin is efficiently taken up by the liver via the ‘multispecific anion transporter’ in an active manner.3 To further examine the fate of pravastatin within the liver, its biliary excretion was studied in a single‐pass liver perfusion system and isolated liver canalicular membrane vesicles (CMVs) using normal (Sprague–Dawley rats; SDRs) and mutant Eisai hyperbilirubinaemic rats (EHBRs). In the liver perfusion experiments, the outflowing drug concentration reached a steady state at 30 min and the extraction ratio was approximately 0·7 in both rat strains. Both the steady state biliary excretion rate and bile flow rate of the EHBR group were 40% of those of SDRS. At steady state, the fraction of unchanged drug in bile was 25–34% in both groups. The concentration ratios of unbound drug in cytosol versus that in sinusoid and of that in bile versus that in cytosol were, respectively, 11 and 87 in SDRs, and 13 and 94 in EHBRs. After correction for the membrane potential (−40 mV in cytosol), the ratios became 49 and 19 in SDR and 58 and 21 in EHBRs, respectively. The finding that all of these values were much larger than unity suggested that active transport occurred from liver to bile, as well as from plasma to liver, in both rat strains. Furthermore, ATP‐dependent uptake of pravastatin was clearly observed in CMVs prepared from EHBRs as well as SDRs, whereas the stimulation by ATP of DNP‐SG transport in CMVs was observed only in SDRs. It was concluded that pravastatin is excreted into bile in high concentrations and a primary active transport mechanism which is maintained in EHBRs contributes to the biliary excretion of this drug.

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On the Mechanism of Na+- and K+-Stimulated Hydrolysis of Adenosine Triphosphate

Abstract: The purification and properties of a Na+‐ and K+‐activated ATPase from ox brain is described. The enzyme preparation is characterized by a high purity and a low content (<1%) of Mg++‐stimulated ATPase.

Cited by 104 publications

References 25 publications

Chromium(III)ATP inactivating (Na⁺+ K⁺)‐ATPase supports Na⁺‐Na⁺ and Rb⁺‐Rb⁺ exchanges in everted red blood cells but not Na⁺,K⁺ transport

Chromium(III)ATP inactivating (Na⁺+ K⁺)‐ATPase supports Na⁺‐Na⁺ and Rb⁺‐Rb⁺ exchanges in everted red blood cells but not Na⁺,K⁺ transport

Evidences for a Sulfhydryl Group in the ATP-Binding Site of (Na+ + K+)-Activated ATPase

Primary Active Transport of Provastatin Across the Liver Canalicular Membrane in Normal and Mutant Eisai Hyperbilirubinaemic Rats

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On the Mechanism of Na+- and K+-Stimulated Hydrolysis of Adenosine Triphosphate

Abstract: The purification and properties of a Na+‐ and K+‐activated ATPase from ox brain is described. The enzyme preparation is characterized by a high purity and a low content (<1%) of Mg++‐stimulated ATPase.

Cited by 104 publications

References 25 publications

Chromium(III)ATP inactivating (Na++ K+)‐ATPase supports Na+‐Na+ and Rb+‐Rb+ exchanges in everted red blood cells but not Na+,K+ transport

Chromium(III)ATP inactivating (Na++ K+)‐ATPase supports Na+‐Na+ and Rb+‐Rb+ exchanges in everted red blood cells but not Na+,K+ transport

Evidences for a Sulfhydryl Group in the ATP-Binding Site of (Na+ + K+)-Activated ATPase

Primary Active Transport of Provastatin Across the Liver Canalicular Membrane in Normal and Mutant Eisai Hyperbilirubinaemic Rats

Contact Info

Product

Resources

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Chromium(III)ATP inactivating (Na⁺+ K⁺)‐ATPase supports Na⁺‐Na⁺ and Rb⁺‐Rb⁺ exchanges in everted red blood cells but not Na⁺,K⁺ transport

Chromium(III)ATP inactivating (Na⁺+ K⁺)‐ATPase supports Na⁺‐Na⁺ and Rb⁺‐Rb⁺ exchanges in everted red blood cells but not Na⁺,K⁺ transport