STEROIDS Steroids represent a large group of compounds which exist in nature, having a common and characteristic structure based on the cyclopentanoperhydrophenanthrene ring (CPPP). It consists of phenanthrene rings (A, B, and C), to which cyclopentane ring (D) is attached. These compounds vary widely in their occurrence and physiological properties despite their common basic structure.…
Sulphur containing lipids are present in various tissues such as liver, kidney, testes, brain, and certain tumours. This sulpholipid is also present in plants. It is localised in the chloroplasts.
Tay-Sachs disease–It is an autosomal recessive disorder. It occurs due to the deficiency of the enzyme hexoaminidase A. Due to the deficiency of this enzyme, gangliosides started to accumulate in brain and nervous tissues.
Gangliosides are glycolipids containing glucose, galactose, and a substance called neuraminic acid and NANA, in addition to fatty acid and sphingosine. Four important types of gangliosides have been isolated from brain tissue: GM-1, GM-2, GM-3, and GD-3.
An inherited disorder of cerebroside metabolism. It is autosomal recessive. β-Glucocerebrosidase cleaves the cerebroside to glucose and ceramide. As a result, large amount of cerebroside accumulated in liver spleen, bone marrow, and also brain leads to mental retardation. This type of disease is termed as Gaucher’s disease.
They are found in brain and myelin sheaths of nerves. They are also known as galactolipids because of their galactose content. They are composed of fatty acid of high molecular weight, sphingosine, and galactose. Its structure is as follows: Four cerebrosides have been identified, according to their fatty acid component. They are as follows:
These may be further subdivided into cerebrosides and gangliosides
It is a phospholipid found in mitochondria (inner membrane) and bacterial wall. It is formed from phosphatidylglycerol. Its structure is as follows:
Plasmalogens are present in brain, nervous tissue, muscles, and mitochondria.
Large accumulation of sphingomyelins may occur in brain, liver, and spleen and lead to a disease called Niemann-Pick disease. Inheritance: Autosomal recessive. Enzyme defect: Deficiency of the enzyme sphingomyleinase, which cannot degraded sphingomyelin in the body; as a result, large amount of sphingomyelin accumulates in tissues and organs of the body, specially in liver, spleen, and brain.