La3+ stabilizes the hexagonal II (HII) phase in phosphatidylethanolamine membranes

摘要: The mechanism of the effects lanthanum ion (La(3+)) and gadolinium (Gd(3+)), which are lanthanides, on function membrane proteins stability structure is not well understood. We investigated La(3+) hexagonal II (H(II)) phase phosphatidylethanolamine (PE) at 20 degrees C by small-angle X-ray scattering. As PE we used DPOPE (dipalmitoleoylphosphatidylethanolamine) membrane, was in L(alpha) 10 mM PIPES buffer (pH 7.4) C. An to H(II) transition occurred 1.4 0 M KCl, 0.4 0.5 KCl above critical concentrations membranes were phase, indicating that stabilizes rather than phase. basis vector length, d, DOPE (dioleoylphosphatidylethanolamine) containing 16 wt% tetradecane excess water condition did change with an increase concentration, suggesting spontaneous curvature these monolayer membranes. chain-melting temperature dielaidoylphosphatidylethanolamine increased lateral compression pressure increased. To elucidate a small percentage 'guest' lipids longer acyl chains average length 'host' concentration guest lipid (DOPE) host (DPOPE) their behavior structure. 12 mol% induced DOPE/DPOPE without changing membrane. found Ca(2+) also compared those La(3+). Based results, have proposed new model for stabilization