Plasmalogens

Plasmalogens are a type of ether phospholipid characterized by the presence of a vinyl ether linkage at the sn-1 position and an ester linkage at the sn-2 position. In mammals, the sn-1 position is typically derived from C16:0, C18:0, or C18:1 fatty alcohols while the sn-2 position is most commonly occupied by polyunsaturated fatty acids (PUFAs). The most common head groups present in mammalian plasmalogens are ethanolamine (designated plasmenylethalomines) or choline (designated plasmenylcholines).

Plasmalogens are found in numerous human tissues, with particular enrichment in the nervous, immune, and cardiovascular system. In human heart tissue, nearly 30–40% of choline glycerophospholipids are plasmalogens. Even more striking is the fact that almost 30% of the glycerophospholipids in the adult human brain and up to 70% of myelin sheath ethanolamine glycerophospholipids are plasmalogens.

Although the functions of plasmalogens have not yet been fully elucidated, it has been demonstrated that they can protect mammalian cells against the damaging effects of reactive oxygen species. In addition, they have been implicated as being signaling molecules and modulators of membrane dynamics.

Plasmalogens were first described by Feulgen and Voit in 1924 based on studies of tissue sections. They treated these tissue sections with acid or mercuric chloride as part of a method to stain the nucleus. This resulted in the breakage of the plasmalogen vinyl-ether bond to yield aldehydes. In turn, the latter reacted with a fuchsine-sulfurous acid stain used in this nuclear staining method and gave rise to colored compounds inside the cytoplasm of the cells. Plasmalogens were named based on the fact that these colored compounds were present in the "plasmal" or inside of the cell.

Biosynthesis of plasmalogens (PLs) begins with association of peroxisomal matrix enzymes GNPAT (glycerone phosphate acyl transferase) and AGPS (alkyl-glycerone phosphate synthase) on the luminal side of the peroxisomal membrane. These two enzymes can physically interact with each other to increase efficiency. Therefore, fibroblasts without AGPS activity have a reduced GNPAT level and activity.

...
Wikipedia