[en] A new procedure of conformational analysis was used to demonstrate that the ionophore conformation is mediated by its membrane environment. In the hydrophobic lipid matrix, the ionomycin-Ca++ complex adopts a conformation well suited for translocation across the interior of the membrane whereas at the lipid-water interface, the Ca++ ion is immersed into the aqueous phase in a position favorable to its complexation or decomplexation. The translocation of Ca++ across the lipid bilayer supposes a reversible transformation of the two conformers. The conformational analysis shows how the dielectric constant discontinuity existing at the lipid-water interface mediates the reversible transformation of one structure into the other.
Disciplines :
Biochemistry, biophysics & molecular biology
Author, co-author :
Brasseur, Robert ; Université Libre de Bruxelles, Laboratoire de Chimie-Physique des Macromolécules aux Interfaces, 1050 Bruxelles, Belgium
Notredame, Miguel; Université Libre de Bruxelles, Laboratoire de Chimie-Physique des Macromolécules aux Interfaces, 1050 Bruxelles, Belgium
Ruysschaert, J M; Université Libre de Bruxelles, Laboratoire de Chimie-Physique des Macromolécules aux Interfaces, 1050 Bruxelles, Belgium