Transbilayer Movement of Phospholipids at the Main Phase Transition of Lipid Membranes: Implications for Rapid Flip-Flop in Biological Membranes

• Published in: Biophysical journal 2002-12, Vol.83 (6), p.3315-3323
• Main Authors: John, Karin, Schreiber, Susanne, Kubelt, Janek, Herrmann, Andreas, Müller, Peter
• Format: Article
• Language: English
• Subjects: 1,2-Dipalmitoylphosphatidylcholine - chemistry; Cell Membrane - chemistry; Cell Membrane - physiology; Diffusion; Dimyristoylphosphatidylcholine - chemistry; Lipid Bilayers - chemistry; Lipids; Liposomes - chemistry; Membrane Lipids - chemistry; Membranes; Motion; Phosphatidylcholines - chemistry; Phosphatidylethanolamines - chemistry; Phospholipids - chemistry; Phosphorus; Structure-Activity Relationship; Temperature
• ISSN: 0006-3495; 1542-0086
• DOI: 10.1016/S0006-3495(02)75332-0

The transbilayer movement of fluorescent phospholipid analogs in liposomes was studied at the lipid phase transition of phospholipid membranes. Two NBD-labeled analogs were used, one bearing the fluorescent moiety at a short fatty acid chain in the sn-2 position (C 6-NBD-PC) and one headgroup-labeled analog having two long fatty acyl chains (N-NBD-PE). The transbilayer redistribution of the analogs was assessed by a dithionite-based assay. We observed a drastic increase of the transbilayer movement of both analogs at the lipid phase transition of DPPC ( T c = 41°C) and DMPC ( T c = 23°C). The flip-flop of analogs was fast at the T c of DPPC with a half-time ( t 1/2) of ∼6–10 min and even faster at the T c of DMPC with t 1/2 on the order of