Inhibitory and stimulatory effects of fluoride on the calcium pump of cardiac sarcoplasmic reticulum

Narayanan, Njanoor; Su, Na; Bedard, Philip

doi:10.1016/0005-2736(91)90149-3

Cited by 37 publications

(26 citation statements)

References 29 publications

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“…Titration of ATPase Activity by (dU) 18 -Poly(rU) was required for efficient inhibition of helicase by ADP and NaF. Because of the heterogeneous nature of poly(rU), determination of an interpretable stoichiometry between enzyme and poly(rU) in the inhibition reaction was not feasible.…”

Section: Comparison Of the Poly(ru)-stimulated Atpase Activity And Thmentioning

confidence: 99%

“…1A for inhibition of the ATPase activity by 1.0 mM ATP and 30 mM NaF were determined with 300 M (nucleobase) poly(rU), (dU) 18 , poly(A), a 45-mer, and a 16-mer as the trapping nucleic acid. Each of these nucleic acids caused a time-dependent inhibition of the ATPase activity in the presence of ATP.…”

Section: Inhibition Of the Atpase Activity Of Helicase By The Combinamentioning

confidence: 99%

“…b was the final ATPase activity, and a was concentration of (dU) 18 that stoichiometrically inhibited the ATPase activity. General Methods-Absorbance and conventional kinetic data were obtained from a Uvikon 860 spectrophotometer at 25°C or on a Spectramax 250 plate reader at 21°C.…”

mentioning

confidence: 99%

“…Titration data for inhibition of ATPase activity by (dU) 18 in the presence of excess NaF, ADP, and Mg 2ϩ was modeled by Equations 9 and 10 for irreversible binding of an inhibitor to an enzyme. The ATPase activity at a total concentration of (dU) 18 was normalized to that of untreated enzyme to give A([(dU) 18 ]).…”

mentioning

confidence: 99%

“…The ATPase activity at a total concentration of (dU) 18 was normalized to that of untreated enzyme to give A([(dU) 18 ]).…”

mentioning

confidence: 99%

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Inhibition of the Hepatitis C Virus Helicase-associated ATPase Activity by the Combination of ADP, NaF, MgCl2, and Poly(rU)

Porter

1998

Journal of Biological Chemistry

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Hepatitis C virus (HCV) helicase has an intrinsic ATPase activity and a nucleic acid (poly(rU))-stimulated ATPase activity. The poly(rU)-stimulated ATPase activity was inhibited by F؊ in a time-dependent manner during ATP hydrolysis. Inhibition was the result of trapping an enzyme-bound ADP-poly(rU) ternary complex generated during the catalytic cycle and was not the result of generating enzyme-free ADP that subsequently inhibited the enzyme. However, catalysis was not required for efficient inhibition by F ؊ . The stimulated and the intrinsic ATPase activities were also inhibited by treatment of the enzyme with F ؊ , ADP, and poly(rU). The inhibited enzyme slowly recovered (t1 ⁄2 ‫؍‬ 23 min) ATPase activity after a 2000-fold dilution into assay buffer. The onset of inhibition by 500 M ADP and 15 mM F ؊ in the absence of nucleic acid was very slow (t1 ⁄2 > 40 min). However, the sequence of addition of poly(rU) to a diluted solution of ADP/NaF-treated enzyme had a profound effect on the extent of inhibition. If the ADP/NaFtreated enzyme was diluted into an assay that lacked poly(rU) and the assay was subsequently initiated with poly(rU), the treated enzyme was not inhibited. Alternatively, if the treated enzyme was diluted into an assay containing poly(rU), the enzyme was inhibited. ATP protected the enzyme from inhibition by ADP/NaF. The stoichiometry between ADP and enzyme monomer in the inhibited enzyme complex was 2, as determined from titration of the ATPase activity ( Hepatitis C virus (HCV)1 genome encodes for an RNA helicase that presumably is essential for viral replication (1). Helicases catalyze the separation of double-stranded nucleic acids into single-stranded nucleic acids with the concomitant hydrolysis of ATP (2). The mechanism of coupling of ATP hydrolysis to double-stranded nucleic acid unwinding is unclear (2, 3). Escherichia coli Rep helicase is the most thoroughly characterized helicase in terms of characterizing the binding of DNA and the associated ATPase activities (3-8). Recently, a crystal structure of the Rep helicase complexed with DNA and ADP has been reported. Helicase motifs Ia, V, and III were implicated in single-stranded DNA binding, motifs I and IV were involved in nucleotide binding, and motifs II and IV possibly functioned in the coupling of nucleotide and single-stranded DNA binding (9). Unfortunately, the protein was crystallized in the absence of a divalent metal cofactor such as Mg 2ϩ , which is required for ATP hydrolysis and nucleic acid unwinding. Crystal structures of DNA helicase from Bacillus stearothermophilus (10) and of RNA helicase from HCV have also been reported. In neither case was the divalent metal cofactor present. Nonetheless, these structures suggested a single nucleotide binding site per monomer.HCV helicase has an intrinsic ATPase activity and an nucleic acid-stimulated ATPase activity. Single-stranded DNA or RNA increased the k cat value of HCV helicase ATPase activity, at most, 50-fold (12). For example, poly(rU) enhanced k cat 30-fold. In contrast,...

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Section: Comparison Of the Poly(ru)-stimulated Atpase Activity And Thmentioning

confidence: 99%

Section: Inhibition Of the Atpase Activity Of Helicase By The Combinamentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

“…The ATPase activity at a total concentration of (dU) 18 was normalized to that of untreated enzyme to give A([(dU) 18 ]).…”

mentioning

confidence: 99%

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Inhibition of the Hepatitis C Virus Helicase-associated ATPase Activity by the Combination of ADP, NaF, MgCl2, and Poly(rU)

Porter

1998

Journal of Biological Chemistry

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Multiple Roles for the Membrane-Associated Ca2+/Calmodulin-Dependent Protein Kinase in the Regulation of Sarcoplasmic Reticulum Function in Heart Muscle

Narayanan¹

1996

Developments in Cardiovascular Medicine

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Phosphorylation and regulation of the Ca2+-pumping ATPase in cardiac sarcoplasmic reticulum by calcium/calmodulin-dependent protein kinase

Narayanan

1998

Alterations of Excitation-Contraction Coupling in the Failing Human Heart

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Inhibitory and stimulatory effects of fluoride on the calcium pump of cardiac sarcoplasmic reticulum

Cited by 37 publications

References 29 publications

Inhibition of the Hepatitis C Virus Helicase-associated ATPase Activity by the Combination of ADP, NaF, MgCl2, and Poly(rU)

Inhibition of the Hepatitis C Virus Helicase-associated ATPase Activity by the Combination of ADP, NaF, MgCl2, and Poly(rU)

Multiple Roles for the Membrane-Associated Ca2+/Calmodulin-Dependent Protein Kinase in the Regulation of Sarcoplasmic Reticulum Function in Heart Muscle

Phosphorylation and regulation of the Ca2+-pumping ATPase in cardiac sarcoplasmic reticulum by calcium/calmodulin-dependent protein kinase

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