compound lipids.ppt
- 1. Complex lipids • Classification • Structure & function of phospholipids & glycolipids 12-10-2011
- 2. Classification Phospholipids Glycolipids Lipoproteins Sulfolipids Complex lipids
- 3. Phospholipids • Complex lipids • Containing phosphoric acid, in addition to fatty acids, nitrogenous base and alcohol Classification Phospholipids Glycerophospholipids Sphingophospholipids
- 4. Micelles are spherical structures that have a nonpolar, hydrophobic environment in the core, and a polar, aqueous environment on the surface. The bile salt-lipid complexes formed in the small intestine are micelles.
- 5. Glycerophospholipids • Membrane lipids • Alcohol is glycerol
- 8. Phosphatidyl choline (Lecithin) • Most abundant phospholipids in cell membrane • Storage form of body’s choline • Widely distributed in animals in liver, brain, nerve tissues, sperm & egg-yolk, having both meatabolic & structural functions • On hydrolysis: glycerol, fatty acids, phosphoric acid, nitrogenous base choline.
- 9. Properties of lecithin Physical properties : • when purified it is a waxy, white substance, becomes brown when exposed to air • Soluble in ordinary fat • hygroscopic
- 10. Chemical properties Lecithin H2O Phosphatidic acid + Choline 1. When aqueous solution of lecithins are shake with sulphuric acid, choline is split off, forming phosphatidic acid Phosphatidic acid Glycerophosphoric acid + 2 Fatty acids H2O 2.
- 11. Dipalmitoyl Lecithin • Important phosphatidylcholine found in lungs • Acts as a surfectant & lower the surface tension in lung alveoli • Absence of DPL, in premature fetus, produces collapse of lung alveoli, which produces Respiratory distress syndrome
- 12. Phospholipase Lecithin Phospholipase A2 Lysolecithin + fatty acid Phospholipase A1 Acyl glycerophosphorylcholine + fatty acid Phospholipase C Phospholipase D 1,2 diacyl glycerol + phosphoryl choline Phosphatidic acid + Choline Lecithin Lecithin Lecithin
- 13. Cephalin • Ethanolamine is the nitrogenous base • They occur with lecithin, particularly rich in brain & nervous tissue
- 14. Phosphatidyl inositol • Phosphatidic acid is esterified to inositol • Important component of cell membrane • Plays vital role in the mediation of hormone action • Inositol as a constituent of phospholipids was first discovered in acid fast bacilli, later in brain & nervous tissue
- 15. Phosphatidyl serine • Cephalin like phospholipid • Contains amino acid serine in place of ethanolamine • Found in brain, nervous tissue & blood
- 16. Plasmalogens • When a fatty acid is attached by an ether linkage at C1 of glycerol in glycerophospholipid, the resultant compound is plasmalogen • Unsaturated fatty acid occurs at C1
- 17. Cardiolipin • Isolated from heart muscle • Consists of two molecules of phosphatidic acid held by an additional glycerol through phosphate groups • Important component of inner mitochondrial membrane • It is only phosphoglyceride that possesses antigenic properties
- 18. Sphingophospholipids • Found in brain & nervous tissue, small amount in other tissues • Does not contain glycerol • In place of glycerol, it contains an 18 carbon unsaturated amino alcohol called sphingosine (sphingol) • On hydrolysis: sphingomyelin yields: one molecules of fatty acid, phosphoric acid, 1 complex unsaturated amino alcohol sphingosine • Sphingosine is attached by an amide linkage to a fatty acid to produce ceramide Example: Sphingomyelins
- 20. Function of phospholipids • Structural components of membranes and regulate membrane permeability • Role in enzyme action e.g. mitochondrial enzyme system involved in oxidative phosphorylation • Role in transport of lipids from intestines • Role in lipid absorption in intestine • Role in electron transport
- 21. Cont… • Lipotropic action of lecithin • Membrane phospholipids as source of arachidonic acid • Role in blood coagulation • Insulation: phospholipids of myelin sheath provide the insulation around the nerve • Cofactor e.g. lipoptotein lipase, triacylglycerol lipase • Phosphatidylinositol are involved in signal transmission across membranes
- 22. Glycolipids 1. Cerebrosides (Glycosphingosides) 2. Gangliosides 3. Sulfolipids
- 23. Cerebrosides (glycosphingosides) • Occur large amounts in the white matter of brain & in the myelin sheaths of nerve • Structure: no glycerol, no phosphoric acid & no nitrogenous base. Thus, cerabrosides on hydrolysis yields: - a sugar, usually galactose but sometimes glucose - a high mol. Weight fatty acid - alcohol, sphingosine or dihydrosphingosine • Contain a ceramide (sphingosine attached to fatty acid) & one or more sugars
- 24. Cont.. • Ceramide + Glucose : Glucocerebroside • Ceramide + Galactose: Galactocerebroside Types of cerebrosides: 1. Kerasin 2. Cerebron 3. Nervon 4. Oxynervon • Function: Nerve conduction in myelin sheath
- 25. Clinical aspect of cerebrosides Gaucher’s disease: • Inherited disorder of cerebrosides metabolism • Autosomal recessive • Enzyme defect: deficiency of beta glucocerebrosidase
- 26. Gangliosides • Highest concentration found in gray matter of the brain • Formed when ceramide oligo-sachharides have at least one molecules of NANA (N-acetyl neuraminic acid, also called sialic acid) attached to them • Ceramide-Glucose-Galactose-NANA • Types of gangliosides: more than 30 types have been isolated • Four important types: GM-1, GM-2, GM-3 & GD-3
- 27. Function: can serve as specific membrane binding sites (receptor sites) for circulating hormones Clinical aspect 1. Tay-Sach’s disease (GM2 Gangliosidosis) • Enzyme defect: deficiency of hexosaminidase A 2. GM1 Gangliosidosis • Due to deficiency of beta galactosidase
- 28. Sulfolipids • Formed when sulfate groups are attached to ceramide oligosaccharides • Important component of membranes of nervous tissue • Failure in degradation of these compounds results in accumulation of these complex in CNS, result in lipid storage diseases
- 29. Clinical aspect 1. Metachromatic Leukodystrophy • Enzyme deficiency: sulfatase 2. Fabry’s disease • Enzyme deficiency: alpha galactosidase 3. Krabbe’s disease • Enzyme deficiency: galactocerebrosidase