The first fluorescence test of vesicle membrane permeability without chromatography

Endosome-type vesicle membranes containing 50% cholesterol were prepared in the presence of 10(-6) M of a beta-tetrapyridiniumporphyrin. Strong fluore scence at 640 nm was observed. Addition of a slight excess (1.5 x 10(-6) M) of copper(II) meso-tetraphenylsulfonate totally quenches the fluorescence in the bulk water volume. The vesicle-entrapped pyridinium porphyrins still fluoresce. In distilled water the residual fluorescence diminishes by less than 10% within 6 h, and in buffered solution it is reduced to 50% within 1 h. In the presence of a harpoon-like disrupter, almost quantitative quenc hing is observed within seconds (dipalmitoylphosphatidylcholine) or 10 min (egg lecithin).