Plasmalogen



A plasmalogen is an ether lipid, with an ether-linked alkene (double bond next to the link), also known as vinyl-ether, at the sn-1 position of the glycerol.

The second carbon (sn-2) has a typical ester-linked fatty acid, and the third carbon usually has a phospholipid head group like choline or ethanolamine.

Functions
In many tissues plasmalogens are minor constituents, but in heart tissue nearly 50% of phosphatidylcholine contains the alkenyl ether at position sn-1. Nervous tissues, testes and kidneys also contain significant amounts of plasmalogens.

Alkenyl ether-containing phospholipids can protect cells against the damaging effects of singlet oxygen, which at high concentrations can kill cells.

Plasmalogens also occur in invertebrates and single cell protozoans. Among bacteria they have been found in many anaerobic species including Clostridia, Megasphaera, and Veillonella.

History
Plasmalogens were first described when studying stained tissue sections.

These tissue sections were pre-treated with mercuric chloride that breaks the vinyl-ether bond and forms aldehydes that later react with a fuschin-sulphurous acid stain, giving rise to coloured compounds inside the cytoplasm of the cells.

Pathology
Zellweger's syndrome is characterized by defects in peroxisome biogenesis resulting in the reduced production of plasmalogen synthesis.