If ceramidase is deficient, ceramide cannot be degraded. This is called Farber’s disease. This disease is characterised by skeletal deformation, dermatitis, and mental retardation.

Deficiency of sphingomyeliase enzyme leads to Niemann–pick disease. Sphingomyelin cannot be degraded in the absence of the enzyme sphingomyelinase. In severe form, liver and spleen are the sites of lipid deposits, and they are enlarged. There is a large amount of sphingosine and a fatty acid.

Sphingomyelin is degraded by lysosomal enzyme sphingomyelinase to form ceramide and phosphorylcholine.

When a fatty acid is attached by an ether linkage rather than by an ester linkage, at carbon 1 of the core glycerol molecule, a plasmalogen is produced. For example, phosphotidyl ethanolamine is the plasmalogen that is similar in structure to phosphotidyl ethanolamine. Myelin contains large amount of ethanolamine plasmalogen, and heart muscle contains large…

Cardiolipin is made up of two molecules of phosphatidic acid combined to a molecule of glycerol. It is the only phosphoglyceride that is antigenic in nature. It is synthesised by phosphotidylglycerol. Phosphatidic acid is a precursor of phosphptidylglycerol, which, in turn, gives rise to cardiolipin in mitochondria.

Ceramide is converted to cerebroside with the help of the enzyme epimerase, which converts UDP. Thus, cerebroside is synthesised.

Ceramide is synthesised in endoplasmic reticulum. First, the amino acid serine following activation by combination with pyridoxal phosphate combines with palmitoyl-CoA to form 3-keto sphingosine. This is converted to dihydrosphingosine in a reductive step utilising NADPH. Dihydro ceramide is formed by combination with acyl-CoA, followed by desaturation to form ceramide.

The structure of cerebrosides is somewhat similar to that of phosphosphingosides. They contain a high molecular weight fatty acid, sphingosine, and either galactose or glucose instead of choline but no phosphoric acid. They have no electric charges since their polar groups are neutral. In general properties, they resemble sphingomyelin. The sphingosine – fatty acid portion…

Cerebrosides are important constituents of brain, where they amount to 8% of the solid matter. These may also occur in tissues other than brain. Since the head group consists of one or more sugar units, cerebrosides are often called glycosphingosides. In Gaucher disease, the cerebrosides appear in relatively large amount in the liver and spleen.…