FIG. 6.

Lipid mixing of vesicles containing gentamicin. The lipid mixing activities of gentamicin-containing DOPE–N-succinyl-DOPE–PEG (69.5:30:0.5) (open squares), DOPC–N-succinyl-DOPE–PEG (69.5:30:0.5) (closed circles), and DPPC-Chol (55:45) (open triangles) were monitored by a resonance energy transfer fluorescence dequenching assay as described in the text. (A) Time course of mixing at pH 4.86 (for the DOPC-containing formulation) and 4.87 (for the DOPE- and DPPC-containing formulations). (B) pH dependence of lipid mixing after 1 min of incubation. (C) pH dependence of lipid mixing after 1 min in serum-free medium containing 20 mM Ca²⁺.