Lipid-water interface mediates reversible ionophore conformational change.
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.
D002118:Calcium; D004987:Ethers; D015759:Ionomycin; D007476:Ionophores; D008081:Liposomes; D008958:Models, Molecular; D008968:Molecular Conformation; D011663:Pulmonary Surfactants; D014867:Water
D004987:Ethers; D007476:Ionophores; D008081:Liposomes; D011663:Pulmonary Surfactants; D014867:Water; D015759:Ionomycin; D002118:Calcium