Na+- and K+-dependent oligomeric interconversion among alphabeta-protomers, diprotomers and higher oligomers in solubilized Na+/K+-ATPase

Protein fractions of a higher-oligomer (H), (alphabeta)(2)-diprotomer (D) and alphabeta-protomer (P) were separated from dog kidney Na(+)/K(+)-ATPase solubilized in the presence of NaCl and KCl. Na(+)/K(+)-dependent interconversion of the oligomers was analysed using HPLC at 0 degrees C. With increa...

Full description

Saved in:
Bibliographic Details
Published in:Journal of biochemistry (Tokyo) 2007-08, Vol.142 (2), p.157-173
Main Authors: Kobayashi, Takayuki, Tahara, Yoshikazu, Takenaka, Hitoshi, Mimura, Kunihiro, Hayashi, Yutaro
Format: Article
Language:English
Subjects:
Animals
Chromatography, High Pressure Liquid
Dogs
Dose-Response Relationship, Drug
Enzyme Activation
Hydrogen-Ion Concentration
Potassium Chloride - pharmacology
Protein Subunits - chemistry
Protein Subunits - isolation & purification
Protein Subunits - metabolism
Sodium Chloride - pharmacology
Sodium-Potassium-Exchanging ATPase - chemistry
Sodium-Potassium-Exchanging ATPase - metabolism
Solubility
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Protein fractions of a higher-oligomer (H), (alphabeta)(2)-diprotomer (D) and alphabeta-protomer (P) were separated from dog kidney Na(+)/K(+)-ATPase solubilized in the presence of NaCl and KCl. Na(+)/K(+)-dependent interconversion of the oligomers was analysed using HPLC at 0 degrees C. With increasing KCl concentrations, the content or amount of D increased from 27.6 to 54.3% of total protein, i.e. DeltaC(max) = 26.7%. DeltaC(max) for the sum of D and H was equivalent to the absolute value of DeltaC(max) for P, regardless of the anion present, indicating that K(+) induced the conversion of P into D and/or H, and Na(+) had the opposite effect. When enzymes that had been denatured to varying degrees by aging were solubilized, DeltaC(max) increased linearly with the remaining ATPase activity. The magnitude of the interconversion could be explained based on an equilibrium of D 2P, assuming 50-fold difference in the K(d) between KCl and NaCl, and coexistence of unconvertible oligomers, which comprised as much as 39% of the eluted protein. Oligomeric interconversion, determined as a function of the KCl or NaCl concentration, showed K(0.5)s of 64.8 microM and 6.50 mM for KCl and NaCl, respectively, implying that oligomeric interconversion was coupled with Na(+)/K(+)-binding to their active transport sites.
ISSN:0021-924X