Sphingomyelins differ radially from cephalin in composition. They are found in brain and nerve tissues. They contain fatty acid, phosphoric acid, choline, and a complex amino alcohol sphingosine or sphingol. Fatty acid is attached to the amino group of sphingosine by amide linkage. The phosphoric acid is attached to one of the hydroxyl group of…
They play an important role in the mechanism of coagulation of blood. Thromboplastin, which is an important factor in coagulation of blood, is a phospholipid.
It is found to occur in brain tissues, nervous tissues, soya bean, and wheatgerm. Inositol is an alcohol and a cyclic compound hexahydroxycyclohexane with molecular formula C6H12O6. Its structure is as follows:
This compound contains amino acid serine instead of ethanolamine. It is found in brain tissues; traces are detected in blood also. Its structure is as follows:
They occur with lecithin, particularly rich in brain and nervous tissue.
Cephalins occur along with lecithin in all plant and animal cells. They are similar structure as that of lecithin but differ from lecithin in that the base attached to phosphoric acid is not choline. It may be one of the three bases, namely ethanolamine, serine, and inositol. Therefore, the three cephalins are known as follows:
Lecithin is readily hydrolysed by boiling with acid and alkalis. Lecithin is hydrolysed by enzymes called lecithinase. There are four different types of lecithinase occur in nature: lecithinase A, lecithinase B, lecithinase C, and lecithinase D. Lecithinase A is found in cobra venom. It is also present in spider venom and poisonous stings. Lecithinase A action…
They are white waxy substances, which become brownish when exposed to air and light, owing to autooxidation. This is due to the presence of unsaturated fatty acid in the molecule. They are soluble in alcohol and other fat solvents. They are hygroscopic and mix well with water to form cloudy, colloidal, and slimy solution. They…