Relationship between the unbinding and main transition temperatures of phospholipid bilayers under pressure

• Published in: Physical review. E, Statistical, nonlinear, and soft matter physics Vol. 69; no. 3 Pt 1; p. 031906
• Main Authors: Harroun, T A, Nieh, M-P, Watson, M J, Raghunathan, V A, Pabst, G, Morrow, M R, Katsaras, J
• Format: Journal Article
• Language: English
• Published: United States 01-03-2004
• Subjects: Binding Sites; Dimyristoylphosphatidylcholine - chemistry; Gels - chemistry; Hydrostatic Pressure; Lipid Bilayers - chemistry; Membrane Fluidity; Membranes, Artificial; Molecular Conformation; Neutron Diffraction - methods; Phase Transition; Phosphatidylcholines - chemistry; Phospholipids - chemistry; Solutions; Transition Temperature
• ISSN: 1539-3755; 1550-2376
• DOI: 10.1103/PhysRevE.69.031906

Using neutron diffraction and a specially constructed high pressure cell suitable for aligned multibilayer systems, we have studied, as a function of pressure, the much observed anomalous swelling regime in dimyristoyl- and dilauroyl-phosphatidylcholine bilayers, DMPC and DLPC, respectively. We have also reanalyzed data from a number of previously published experiments and have arrived at the following conclusions. (a). The power law behavior describing anomalous swelling is preserved in all PC bilayers up to a hydrostatic pressure of 240 MPa. (b). As a function of increasing pressure there is a concomitant decrease in the anomalous swelling of DMPC bilayers. (c). For PC lipids with hydrocarbon chains >or=13 carbons the theoretical unbinding transition temperature T small star, filled is coupled to the main gel-to-liquid crystalline transition temperature T(M). (d). DLPC is intrinsically different from the other lipids studied in that its T small star, filled is not coupled to T(M). (e). For DLPC bilayers we predict a hydrostatic pressure (>290 MPa) where unbinding may occur.