LIQUID ORDERED PHASE

The 'liquid ordered phase' is a liquid crystalline phase of biological importance. It occurs whenever there is cholesterol and phospholipid and/or sphingolipids e.g sphingomyelin present. This phase has been related to lipid rafts that may exist in plasma membranes.

Contents

Definition

History

References

Definition

The liquid ordered phase can be defined as:

★ fluid and lamellar phase

★ acyl hydrocarbon chains are in the all-''trans'' state

★ rapid lateral diffusion

★ ²H-NMR quadrupolar splitting is ca. 50kHz

★ WAXS scattering pattern centered by broad diffraction peak at 4.2Å

History

This was first called the liquid ordered phase by Ipsen et al. (1987). However, it has also been called the LG_I subgel phase by Huang et al. (1993) and the β phase by Vist and Davis (1990).

References

★ Ipsen, J. H., G. Karlstrom, O. G. Mouritsen, H. Wennerstrom, and M. J. Zuckermann. 1987. Phase equilibria in the phosphatidylcholine-cholesterol system. Biochim. Biophys. Acta. 905:162–172.

★ Huang TH, Lee CWB, Dasgupta SK, Blume A, Griffin RG. 1993. "A C-13 and H-2 Nuclear-Magnetic-Resonance Study of Phosphatidylcholine Cholesterol Interactions - Characterization of Liquid-Gel Phases." Biochemistry 32(48):13277-13287

★ Vist MR, Davis JH. 1990. "Phase-Equilibria of Cholesterol Dipalmitoylphosphatidylcholine Mixtures - H-2 Nuclear Magnetic-Resonance and Differential Scanning Calorimetry." Biochemistry 29(2):451-464.