Biophysical Journal 59: 252-255 (1991)
© 1991 the Biophysical Society

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Yao, H. Articles by Hatta, I. Search for Related Content PubMed Articles by Yao, H. Articles by Hatta, I.

Metastable ripple phase of fully hydrated dipalmitoylphosphatidylcholine as studied by small angle x-ray scattering

Haruhiko Yao ^*, Sinzi Matuoka ^*, Boris Tenchov  and Ichiro Hatta ^*

Department of Applied Physics, Nagoya University, Nagoya 464-01, Japan
Central Laboratory of Biophysics, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria

ABSTRACT

Fully hydrated dipalmitoylphosphatidylcholine (DPPC) undergoes liquid crystalline to metastable P_ß, phase transition in cooling. A small angle x-ray scattering study has been performed for obtaining further evidence about the structure of this phase. From a high-resolution observation of x-ray diffraction profiles, a distinct multipeak pattern has become obvious. Among them the (01) reflection in the secondary ripple structure is identified clearly. There are peaks assigned straightforwardly to (10) and (20) reflections in the primary ripple structure and peaks assigned to (10) and (20) reflections in the secondary ripple structure. Therefore the multipeak pattern is due to superposition of the reflections cause by the primary and secondary ripple structures. The lattice parameters are estimated as follows: for the primary ripple structure a = 7.09 nm, b = 13.64 nm, and = 95°, and for the secondary ripple structure a = 8.2 nm, b = 26.6 nm, and = 90°. The lattice parameters thus obtained for the secondary ripple structure are not conclusive, however. The hydrocarbon chains in the primary ripple structure have been reported as being tilted against the bilayer plane and, on the other hand, the hydrocarbon chains in the secondary ripple structure are likely to be perpendicular to the bilayer plane. This fact seems to be related to a sequential mechanism of phase transitions. On heating from the L_ß, phase where the hydrocarbon chains are tilted the primary ripple structure having tilted hydrocarbon chains takes place and on cooling from the L phase where the hydrocarbon chains are not tilted the secondary ripple structure with untilted chains tends to be stabilized. It appears that the truly metastable ripple phase is expressed by the second ripple structure although in the course of the actual cooling transition both the secondary and primary ripple structures form and coexist.

This article has been cited by other articles:

				T. Kaasgaard, C. Leidy, J. H. Crowe, O. G. Mouritsen, and K. Jorgensen Temperature-Controlled Structure and Kinetics of Ripple Phases in One- and Two-Component Supported Lipid Bilayers Biophys. J., July 1, 2003; 85(1): 350 - 360. [Abstract] [Full Text] [PDF]