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- 1. Biochemistry of Lipids Lipids Classification By Dr. Samina Professor, Biochemistry, CPMC.
- 2. Learning Objectives By the end of this lecture students must be able to: ❑ Sub-claasify Sphingo-phospholipids ❑Classify Glycolipids into subclasses ❑ Discuss the difference of Gangliosides and cerebrosides in glycolipids ❑ Differentiate between different lipo-proteins and their role in atherosclerosis
- 3. Classification of Lipids Simple Compound/Complex Derived/Associated Neutral Fats Waxes Phospholipids Glycolipids Sulfolipids Gangliosides Glycero Phospholipids Sphingo Phospholipids Phosphatidic acids Lecithin s Cephalin s Plasmalogens Sphingomyelin Lipo proteins Cerebrosides Steroids Trepens VLDL LDL IDL HDL Cardiolipin Phosphatidyl inositol/serine Fat soluble vitamins Miscellaneous Carotenoids Amino lipids
- 5. Sphingo-phospholipids • A phospholipid with sphingosine instead of the glycerol • Important in the myelin sheath that surrounds most nerve fibers, Grey matter –Sphingomyelin (found in brain & nervous tissue). • Found in special areas of membranes… known as Lipid rafts.
- 6. Sphingo-phosopho lipids • Sphingosine + fatty acid + PO4+ choline or ethanol amine • Ceramides.. Highly hydrophobic molecules • Produced in response to stress stimuli (TNFs, radiation, chemotherapeutic drugs)…Functions in different ways: • Targets & activates enzymes (kinases, phosphatases) • Regulates membrane structure • Can act as a signaling molecule. The most well-known functions of ceramides as cellular signals include regulators of multiple cellular processes (apoptosis, cell senescence, cell cycle, differentiation) Ceramide
- 7. Sphingo-phosopho lipids • Sphingomyelins • 10-20% present in membranes. • Brain, nerve tissues are rich in spingomyelins .. Small quantities in blood & other tissues. • Sphingomyelinase enzyme act on spingomyelins… deficiency… accumulation of sphingomyelins in spleen & brain. cause Niemann Pick’s disease (mental retardation & enlargement of storage tissues)
- 8. Phospholipids related Diseases – Respiratory Distress syndrome.. Defic. of lecithin – Excess accumulation of sphingolipid – Caused by an absent, mis made, or deficient enzyme that breaks down the lipid – Multiple Sclerosis: Loss of myelin ---- sphingomyelin – Slowing & eventual cessation of nerve impulse – Weakness, lack of co-ordination & speech and vision problems
- 9. Phospholipid Phospholipids join a bilayer to form a cell membrane. Polar Head Nonpolar Tail The Cell Membrane
- 10. Glycolipids • glycerol Sphingosine + 1 fatty acid + sugar 1- Cerebrosides 2- Gangliosides – Present in outer leaflet of plasma membrane… cell surface CHO • The major glycolipids found in animal tissues are glycosphingolipids. – Function in cell adhesion & self-identity markers – Important in the determination of an individual's blood group • They contain ceramide &one or more sugars. e.g.Galactosylceramide
- 11. Glycolipids • Glycolipids are also present in sulfated form in myelin sheath (white matter) of brain… sulfatides
- 12. •A cerebroside is a sphingolipid (ceramide) with a monosaccharide such as glucose or galactose as polar head group. It contains a number of characteristic C24 fatty acids e.g., cerebronic acid. A ganglioside is a ceramide with a polar head group that is a complex oligosaccharide, including the acidic sugar derivative sialic acid. Cerebrosides & gangliosides, collectively called glycosphingolipids, are commonly found in the outer leaflet of the plasma membrane bilayer, with their sugar chains extending out from the cell surface. Glycolipids
- 13. Ceramide • Highly hydrophobic molecules • Produced in response to stress stimuli (TNFs, radiation, chemotherapeutic drugs) Functions in different ways: • Targets and activates enzymes (kinases, phosphatases) • Regulates membrane structure • Ceramide can actually act as a signaling molecule. The most well-known functions of ceramides as cellular signals include regulators of multiple cellular processes (apoptosis, cell senescence, cell cycle, differentiation)
- 14. Difference between Cerebroside & Gangliosides • Cerebrosides • Sphing + F.A + Gal • White matter, myelin sheath Diff. Types --- gluco-cer • Kerasins, cerebron, Nervon • Gaucher’s disease– Genetic disorder in cerebroside metabolism • Gangliosides • Sphing + F.A+ 2Gal+ NAC+ Sialic acid • Diff. Types – GM1,GM2, GM3 etc. • Grey matter, nervous tissue, hormone receptor, receptor for cholera toxin(GM3) influenza
- 15. Glycolipids polar group (containing sugars, more bulky) Backbone (derived from serine in animals) nonpolar fatty acid tail (mainly saturated and longer tails Gaucher’s disease-- enzyme gucocerbrosidase defi. The fat builds up, especially in liver, spleen, and bone marrow, causing problems.. mental retardation & bone pain G represents.. Ganglioside M -------------… monosialo specie 1,2,3--------…Chromatographic migration
- 17. SULFOLIPIDS ( sulfatides) • Lipids characterised by possessing sulphate groups along with oligosaccharides • Components of nervous tissue membranes… inborn error is known as lipid storage diseases
- 18. Key Points • Lipids when have phosphate group with sphingosine alcohol…. Sphingo-Phospholipids… Sphingomyelins • Glycolipids--- have one or more sugar units with alcohol glycerol or sphingosine Sulpho lipids…. Components of nervous tissue membrane • Gaucher’s disease– Caused by deficiency of enzyme gluco-cerebrosidase Cerebrosides Gangliosides
- 19. Next topic of Discussion • Lipoproteins, Cholesterol and Miscellaneous lipids
- 21. THANK YOU