(NA++K+)-ATPASE - EFFECTS OF DETERGENTS ON THE CROSS-LINKING OF SUBUNITS IN THE PRESENCE OF CU2+ AND ORTHO-PHENANTHROLINE

When (Na+ + K+)-ATPase is reacted with Cu2+ or Cu2+-phenanthroline, cross-linking of the two subunits (α and β) occurs. The major products are α,β- and α,α-dimers. The α,β-dimer is unstable in the presence of EDTA, but becomes stable when it is first exposed to digitonin or Triton X-100. Conversion of α-Cu2+ -β to α-S-S-β is suggested. If the enzyme that is pretreated with these detergents is used, only the stable α,β-dimer is obtained, and the formation of α,α-dimer is inhibited. The data are consistent with α2β2 quaternary structure of the enzyme. © 1979.