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Filipin as a fluorescent probe for the location of cholesterol in the membranes of fragmented sarcoplasmic reticulum

1973; Elsevier BV; Volume: 291; Issue: 1 Linguagem: Inglês

10.1016/0005-2736(73)90060-6

1879-2642

W. Drabikowski, Elżbieta Lągwińska, M.G. Sarzała,

Photoreceptor and optogenetics research

A polyene antibiotic, filipin, when excited at 360 nm in solvents of low polarity, exhibits a strong fluorescence with a maximum at 480 nm. Mixed lecithin-cholesterol micelles, but not aqueous dispersions of cholesterol, also cause an increase of filipin fluorescence. Filipin binds to the vesicles of fragmented sarcoplasmic reticulum. The binding is considerably decreased after removal of cholesterol and abolished after lipid depletion. A restoration of filipin binding is achieved in the former case by rebinding of cholesterol, in the latter case only by the cholesterol-phospholipid micelles. Cholesterol additionally bound to intact vesicles does not cause an increase of binding of filipin. An enhancement of filipin fluorescence intensity is observed on its binding to the fragmented sarcoplasmic reticulum, indicating binding to regions of low polarity. Fluorescence with a maximum at about 340 nm, exhibited by sarcoplasmic reticulum vesicles by excitation at 280 nm, decreases in the presence of filipin with a concomitant appearence of fluorescence with a maximum at 480 nm. These results indicate an energy transfer from tryptophan residues to filipin.