Classification of Phospholipids

Classification

Phospholipids are classified into two types.

1.        Glycerophospholipids (or) Phosphoglycerides that contain glycerol as alcohol.

2.        Sphingophospholipids that contain sphingosine as alcohol.

Glycerophospholipids

These are the major lipids that occur in biological membranes. They present in all plant and animal cells. They are abundantly present in heart, brain, kidney, egg yolk and soyabean. The important glycerophospholipids are lecithin, cephalin, phosphotidyl inositol, cardiolipin and plasmalogen.

The lecithins contain glycerol, fatty acids, phosphoric acid and choline (nitrogenous base). Lecithins generally contain a saturated fatty acid at a1 position and an unsaturated fatty acid at β postition.

The cephalin contains glycerol, fatty acids, phosphoric acids and ethanol amine as nitrogenous base.

Phosphatidyl inositol contains a hexahydric alcohol called as inositol.

Plasmalogens posses an ether link in a1 position instead of ester link. The alkyl radical is an unsaturated alcohol and they are found in brain and nervous tissue

Spingophospholipids

These are present in plasma membrane and myelin sheath. They are amphipathic lipids having polar head and non-polar tail. They contain an amino alcohol called shingosine. It is attached to a fatty acid by an amide linkage to form ceramide. Ceramide is linked to phosphoryl choline to form sphingomyelin, which is an important member of sphingophospholipids.