High pressure volumetric measurements in dipalmitoylphosphatidylcholine bilayers

• Published in: Biochimica et biophysica acta Vol. 859; no. 1; pp. 10 - 14
• Main Authors: TOSH, R. E, COLLINGS, P. J
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier 10.07.1986; North-Holland
• Subjects: Artificial membranes and reconstituted systems; Atmospheric Pressure; Biological and medical sciences; Chemical Phenomena; Chemistry, Physical; Fundamental and applied biological sciences. Psychology; Lipid Bilayers; Membrane physicochemistry; Molecular biophysics; Pulmonary Surfactants; Temperature; Isothermal compressibility; Bilayer; Phase transitions; Mesomorphic state
• ISSN: 0006-3002; 1878-2434
• DOI: 10.1016/0005-2736(86)90312-3

The one previously reported high pressure volumetric experiment on a phospholipid bilayer investigated a region of pressure between 0 and 25 MPa and obtained isothermal compressibility values for the liquid crystal and intermediate phases which differed by more than a factor of ten. We report new volumetric measurements around the main transition in dipalmitoylphosphatidylcholine (DPPC) from 0 to 100 MPa. The isothermal compressibility data for the two phases are of the same order of magnitude, and the experimentally determined coexistence curve, specific volume dependence, and volume discontinuity values are compared with the predictions of the phenomenological theory according to Sugar and Tarjan ((1982) Sov. Phys. Crystallogr. 27, 4-5). Significant discrepancies between this theory and experiment are found. Finally, the data indicate that steric interactions play a more dominant role in the main transition of phospholipid bilayers than in transitions in most thermotropic liquid crystals.