Ceramide belongs to the group of sphingolipids and is constituted by the amide ester of the sphingoid base D-erythro-sphingosine and a fatty acid of C16 through C32 chain length. At present, the differential biological function of different ceramide species is unknown and, thus, the term ceramide is used collectively to represent all long-chain ceramide molecules.
Formation of Ceramide
Ceramide molecules are very hydrophobic and exclusively present in membranes. Sphingomyelin, the choline-ester of ceramide, is hydrolyzed by acid, neutral, and alkaline sphingomyelinases to release ceramide. Ceramide is also de novo synthesized via a pathway involving the serine-palmitoyl-CoA transferase and a variety of partly cell type-specific ceramide synthases. Under some circumstances, ceramide can be also formed from sphingosine by a reverse activity of the acid ceramidase.
Ceramide-Induced Changes of Biological Membranes
The formation of ceramide within biological...