Interaction of fluorescent phospholipids with cyclodextrins

Abstract

Fluorescent analogs of phospholipids are often employed to investigate the structure and dynamics of lipids in membranes. Some of those studies have used cyclodextrins e.g., to modulate the lipid phase. However, the role of the fluorescence moiety of analogs for the interaction between cyclodextrins and fluorescent lipids has not been investigated so far in detail. Therefore, in the present study the interaction of various fluorescent phospholipid analogs with methylated α-, β- and γ- cyclodextrins was investigated. The analogs differed in their structure, in the length of the fatty acyl chain, in the position of the fluorescence group, and in the attached fluorescence moiety (7-nitrobenz-2-oxa-1,3-diazol-4-yl (NBD) or dipyrrometheneboron difluoride (BODIPY)). In aqueous buffer, cyclodextrins bind fluorescent lipids disturbing the organization of the analogs. When incorporated into lipid vesicles, analogs are selectively extracted from the membrane upon addition of cyclodextrins. The results show that the interaction of cyclodextrins with fluorescent phospholipids depends on the cyclodextrin species, the fluorescence moiety and the phospholipid structure. The presented data should be of interest for studies using fluorescent phospholipids and cyclodextrins, since the interaction between the fluorescence group and the cyclodextrin may interfere with the process(es) under study.

Keywords: Cyclodextrin; Fluorescent phospholipid; Membrane dynamics; Membrane structure; Phospholipid.