Plasmenylcholines

Plasmenylcholines, also known as plasmenylcholine or plasmalogen phosphatidylcholine, are a subclass of glycerophospholipids characterized by an ether-linked vinyl-ether (1-alkenyl) bond at the sn-1 position and a phosphocholine head group at the glycerol backbone. The sn-2 position typically carries an acyl chain. This combination gives plasmenylcholines the defining sn-1 vinyl-ether linkage and a choline-containing headgroup.

Biochemical presence and biosynthesis: Plasmenylcholines are abundant components of cellular membranes, notably in heart and brain tissue, and are found across many tissues in mammals. Their biosynthesis begins in peroxisomes, where an ether bond is formed to yield alkyl-dihydroxyacetone phosphate precursors, followed by desaturation to the vinyl ether and esterification at the sn-2 position. The final step adds the phosphocholine head group, yielding plasmenylcholine. Peroxisomal disorders can disrupt this pathway and reduce plasmalogen levels.

Function and significance: Plasmenylcholines are thought to contribute to membrane structure and fluidity, particularly in lipid rafts and microdomains. The vinyl-ether linkage provides resistance to oxidative stress and may serve as a trap for reactive species, endowing plasmalogens with antioxidant properties. They also participate in signaling and may act as reservoirs for polyunsaturated fatty acids released during remodeling.

Clinical relevance and measurement: Altered plasmenylcholine levels have been reported in neurodegenerative diseases and cardiovascular conditions, and marked reductions are observed in peroxisomal biogenesis disorders. Analytical measurement is typically performed by lipidomics approaches, including mass spectrometry, which can distinguish vinyl-ether-containing plasmalogens from diacyl phospholipids based on characteristic mass fragments.