Stabilization of Na,K-ATPase by ionic interactions

E. Fodor, Natalya U. Fedosova, Csilla Ferencz, Derek Marsh, T. Páli, Mikael Esmann

Research output: Contribution to journalArticle

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Abstract

The effect of ions on the thermostability and unfolding of Na,K-ATPase from shark salt gland was studied and compared with that of Na,K-ATPase from pig kidney by using differential scanning calorimetry (DSC) and activity assays. In 1 mM histidine at pH 7, the shark enzyme inactivates rapidly at 20 °C, as does the kidney enzyme at 42 °C (but not at 20 °C). Increasing ionic strength by addition of 20 mM histidine, or of 1 mM NaCl or KCl, protects both enzymes against this rapid inactivation. As detected by DSC, the shark enzyme undergoes thermal unfolding at lower temperature (Tm ≈ 45 °C) than does the kidney enzyme (Tm ≈ 55 °C). Both calorimetric endotherms indicate multi-step unfolding, probably associated with different cooperative domains. Whereas the overall heat of unfolding is similar for the kidney enzyme in either 1 mM or 20 mM histidine, components with high mid-point temperatures are lost from the unfolding transition of the shark enzyme in 1 mM histidine, relative to that in 20 mM histidine. This is attributed to partial unfolding of the enzyme due to a high hydrostatic pressure during centrifugation of DSC samples at low ionic strength, which correlates with inactivation measurements. Addition of 10 mM NaCl to shark enzyme in 1 mM histidine protects against inactivation during centrifugation of the DSC sample, but incubation for 1 h at 20 °C prior to addition of NaCl results in loss of components with lower mid-point temperatures within the unfolding transition. Cations at millimolar concentration therefore afford at least two distinct modes of stabilization, likely affecting separate cooperative domains. The different thermal stabilities and denaturation temperatures of the two Na,K-ATPases correlate with the respective physiological temperatures, and may be attributed to the different lipid environments.

Original languageEnglish
Pages (from-to)835-843
Number of pages9
JournalBBA - Biomembranes
Volume1778
Issue number4
DOIs
Publication statusPublished - Apr 2008

Fingerprint

Adenosine Triphosphatases
Stabilization
Sharks
Histidine
Enzymes
Differential Scanning Calorimetry
Differential scanning calorimetry
Temperature
Kidney
Centrifugation
Hot Temperature
Ionic strength
Osmolar Concentration
Salt Gland
sodium-translocating ATPase
Denaturation
Hydrostatic Pressure
Hydrostatic pressure
Cations
Assays

Keywords

  • Denaturation
  • Differential scanning calorimetry
  • Electrostatic screening
  • Na,K-ATPase
  • Pig kidney
  • Shark salt gland

ASJC Scopus subject areas

  • Biochemistry
  • Cell Biology
  • Biophysics

Cite this

Stabilization of Na,K-ATPase by ionic interactions. / Fodor, E.; Fedosova, Natalya U.; Ferencz, Csilla; Marsh, Derek; Páli, T.; Esmann, Mikael.

In: BBA - Biomembranes, Vol. 1778, No. 4, 04.2008, p. 835-843.

Research output: Contribution to journalArticle

Fodor, E, Fedosova, NU, Ferencz, C, Marsh, D, Páli, T & Esmann, M 2008, 'Stabilization of Na,K-ATPase by ionic interactions', BBA - Biomembranes, vol. 1778, no. 4, pp. 835-843. https://doi.org/10.1016/j.bbamem.2007.12.006
Fodor, E. ; Fedosova, Natalya U. ; Ferencz, Csilla ; Marsh, Derek ; Páli, T. ; Esmann, Mikael. / Stabilization of Na,K-ATPase by ionic interactions. In: BBA - Biomembranes. 2008 ; Vol. 1778, No. 4. pp. 835-843.
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