The liquid ordered phase is a liquid crystal

Liquid crystal

Liquid crystals are a state of matter that have properties between those of a conventional liquid and those of a solid crystal. For instance, an LC may flow like a liquid, but its molecules may be oriented in a crystal-like way. There are many different types of LC phases, which can be...

line phase of biological importance. It occurs in many lipid mixtures combining cholesterol

Cholesterol

Cholesterol is a complex isoprenoid. Specifically, it is a waxy steroid of fat that is produced in the liver or intestines. It is used to produce hormones and cell membranes and is transported in the blood plasma of all mammals. It is an essential structural component of mammalian cell membranes...

 with a phospholipid

Phospholipid

Phospholipids are a class of lipids that are a major component of all cell membranes as they can form lipid bilayers. Most phospholipids contain a diglyceride, a phosphate group, and a simple organic molecule such as choline; one exception to this rule is sphingomyelin, which is derived from...

 and/or sphingolipid

Sphingolipid

Sphingolipids are a class of lipids containing a backbone of sphingoid bases, a set of aliphatic amino alcohols that includes sphingosine. They were discovered in brain extracts in the 1870s and were named for the mythological Sphinx because of their enigmatic nature. These compounds play...

s e.g. sphingomyelin

Sphingomyelin

Sphingomyelin is a type of sphingolipid found in animal cell membranes, especially in the membranous myelin sheath that surrounds some nerve cell axons. It usually consists of phosphorylcholine and ceramide...

. This phase has been related to lipid rafts that may exist in plasma membranes.

Definition

The liquid ordered phase can be defined as:

• fluid and lamellar
  Lamellar structure
  Lamellar structures or microstructures are composed of fine, alternating layers of different materials in the form of lamellae. They are often observed in cases where a phase transformation front moves quickly, leaving behind two solid products, as in rapid cooling of eutectic or eutectoid ...
  
   phase
• acyl
  Acyl
  An acyl group is a functional group derived by the removal of one or more hydroxyl groups from an oxoacid, including inorganic acids.In organic chemistry, the acyl group is usually derived from a carboxylic acid . Therefore, it has the formula RCO-, where R represents an alkyl group that is...
  
   hydrocarbon chains are in the all-trans state
• rapid lateral diffusion
• ²H-NMR
  NMR
  NMR may refer to:Applications of Nuclear Magnetic Resonance:* Nuclear magnetic resonance* NMR spectroscopy* Solid-state nuclear magnetic resonance* Protein nuclear magnetic resonance spectroscopy* Proton NMR* Carbon-13 NMR...
  
   quadrupolar splitting is ca. 50 kHz
• Wide angle X-ray scattering
  Wide angle X-ray scattering
  Wide angle X-ray scattering or Wide angle X-ray diffraction is an X-ray diffraction technique that is often used to determine the crystalline structure of polymers...
  
  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).