Lipids Classification PDF

# LIPIDS ## CLASSIFICATION - SIMPLE - Fats - Waxes - COMPOUND - Phospholipids - Glyco-lipids - DERIVED - Glycerol - Cholesterol - Fatty acids - Bile Salts - Ketone ## LIPIDS - Simple lipids - Esters of fatty acids - Fats - Esters of fatty...

# LIPIDS ## CLASSIFICATION - SIMPLE - Fats - Waxes - COMPOUND - Phospholipids - Glyco-lipids - DERIVED - Glycerol - Cholesterol - Fatty acids - Bile Salts - Ketone ## LIPIDS - Simple lipids - Esters of fatty acids - Fats - Esters of fatty acids and glycerol - Waxes - Esters of long chain fatty acids and long chain alcohols - Compound lipids - Esters of fatty acids and alcohol contain other groups also - Derived lipids - Composed of hydrocarbon rings and a long hydrocarbon side chain ## Simple Lipids are Esters of Fatty acids with Alcohol - Simple Lipids are Further Classified: - Fats: Esters of Fatty acids with Glycerol. - Triacylglycerols - Waxes: Esters of Fatty acids with higher alcohols ## Glycerides - Glycerides (acylglycerols) are esters formed from glycerol and fatty acids. - Monoglycerides - Diglycerides - Triglycerides ## Simple and Mixed Triacylglycerols - Simple: - Same type of fatty acids on all the three hydroxyl groups - Mixed: - Two or all the three fatty acids are different ## Triglycerides TG: - Triglyceride give energy in case of absence of carbohydrates - Triglycerides are stored in adipose tissue - Elevated in obese or diabetic patients. Level increases from eating simple sugars or drinking alcohol. Associated with heart and blood vessel disease. ## SIMPLE TRIGLYCERIDES - $CH_2-O-CO-C_{17}H_{35}$ (stearic acid) - $CH-O-CO-C_{17}H_{35}$ (stearic acid) - $CH_2-O-CO-C_{17}H_{35}$ (stearic acid) ## MIXED TRIGLYCERIDES - $CH_2-O-CO-C_{17}H_{35}$ (stearic acid) - $CH-O-CO-C_{17}H_{35}$ (stearic acid) - $CH_2-O-CO-C_{}15H_{33}$ (palmitic acid) ## Significance of Triacylglycerols (Fats) - Energy: - Double the amount that of Glucose - Dietary fats are carriers of vitamins: - Fat-soluble vitamins like vitamin A, D, E and K are usually dissolved in dietary fats - Provision of Essential fatty acids: - α-Linolenic acid (omega-3 fatty acid) and Linoleic acid (omega-6 fatty acid) ## Figure 4: Glycerides - $CH_2-OH$ - $CH-OH$ - $CH_2-OH$ Glycerol - $CH_2-O-C-R_1$ - $CH-OH$ - $CH_2-OH$ Monoglyceride - $CH_2-O-C-R_1$ - $CH-O-C-R_2$ - $CH_2-OH$ Diglyceride - $CH_2-O-C-R_1$ - $CH-O-C-R_2$ - $CH_2-O-C-R_3$ Triglyceride ## Adipose Tissue - Location: beneath the skin (subcutaneous fat), around internal organs (visceral fat), in bone marrow (yellow bone marrow), intermuscular (Muscular System) and in the breast (breast tissue) - Adipose tissue: the link between obesity and cardiovascular disease. - Chronic overnutrition and lack of physical activity result in excess deposition of adipose tissue which plays a key role in the pathophysiology of cardiovascular disease (CVD). ## Phospholipids - Glycerophospholipids - Sphingolipids - Fatty acid - Fatty acid - $O_3$ Alcohol - Sphingosine - Fatty acid - $PO_4$ Choline - Sphingolipids - Sphingosine - Fatty acid - Gl ## Complex/Compound Lipids - Esters of fatty acids with alcohol, containing non-lipid Group ($PO_4$, Nitrogenous base, or sugar) - Compound Lipids are Further Classified as: - Phospholipids are lipids with a phosphate group - Glycolipids are lipids with a carbohydrate attached by a glycosidic bond. ## PHOSPHOLIPIDS - Phosphate group apart from Alcohol and acids - Phospholipids further classified in - Glycerophospholipids - Sphingophospholipids ## Phospholipids: - Major constituents of all cell membranes - Components of bile - Anchor some proteins in membranes - Signal mediators - Components of lungs - Components of lipo ## PHOSPHOLIPIDS - Glycerophospholipids - Phosphatidic acid is the parent compound of glycerophospholipids - Glycerol backbone - 2 Fatty acids - $PO_4$ ## Amphipathic Phospholipids - Hydrophilic and hydrophobic components together in a single molecule. - Charged end (polar head): - Phosphate-Alcohol - Phosho-Choline - Phospho-Ethanolamine - Non-polar tails: - Fatty acids ## Phosphoglycerides Amphipathic - Because they have both polar(hydrophilic) and non-polar(hydrophobic) regions in their structure ## 1. Glycerophospholipids - $PA + serine = phosphatidylserine (PS)$ - $PA + ethanolamine = phosphatidylethanolamine (PE, cephalin)$ - $PA + choline = phosphatidylcholine (PC$, lecithin) - $PA + glycerol = phosphatidylglycerol (PG)$ ## 2. Cardiolipin - Two molecules of PA esterified through their phosphate groups to an additional molecule of glycerol is called cardiolipin or diphosphatidylglycerol - Cardiolipin is found in inner mitochondrial membranes - Where it maintains the structure and function of certain respiratory complexes of the ETC ## 3. Plasmalogens - Plasmalogens have an ether-linked fatty acid at C-1 of glycerol, instead of ester-linked fatty acid - Ether glycerophospholipid is plasmalogen - Abundant in nerve tissues - Abundant in heart muscles ## 4. Platelet activating factor (PAF) - Second example of an ether glycerophospholipid is PAF - It has potent physiologic actions - Causes platelets to aggregate and activate - Triggering potent thrombotic and acute inflammatory events - Bronchoconstriction ## Sphingolipids - schematic structure - Ceramide - N-Acylsphingosine - A sphingophospholipid - Sphingosine - Fatty acid - Phosphate - Alcohol - The "head" group - A glycolipid - Sphingosine - Fatty acid - Saccharide ## 2. Sphingophospholipids (backbone is Sphingosine) - Ceramide is the parent compound for sphingophospholipid - Sphingosine + Fatty acid = Ceramide - Polar head: - Phosphate-Alcohol - Sphingosine - F ## Sphingomyelins: - Ceramide + Phosphorylcholine = Sphingomyelin - Sphingomyelins are found in the myelin sheath of nervous tissue - Sphingomyelin of the myelin sheath protects and insulates neuronal fiber of the central nervous system ## Sphingolipidoses - Sphingolipidoses result from deficiencies of specific degradative enzymes - They are diagnosed by - Accumulation of specific sphingolipid - Enzyme activity measurements - Histologic examination of affected tissue ## Sphingolipid Storage Diseases | Disease | Symptom | Sph. Lip | Enzyme | |----------------|------------------------------------------|-----------------------|-----------------------------------------| | Tay-Sachs | Blindness, muscles weak | Ganglioside GM₁ | β-hexose-aminidase A | | Gaucher's | Liver & spleen enlarge | Gluco-cerebroside | β-glucosidase | | Krabbe's | Demyelation, Mental Retardation | Galacto-cerebroside | β-galactosidase | | Nieman-Pick | Mental Retardation | Sphingomyelin | Sphingomyelinas | ## Glycolipids - Glycosphingolipids are essential components of membranes but they are found in greatest amounts in nerve tissues. - They are located in the outer leaflet of plasma membrane where they are involved in cellular interaction ## Glycolipids - Cerebrosides contain a single sugar (Glu or Gal) - Gangliosides are acidic glycosphingolipids. They contain oligosaccharides with terminal, charged N-acetyl neuraminic acids (NANA). ## Cerebrosides are classified into - Galacto-cerebrosides. - Head group is galactose - Mainly present in cell membrane of brain cells - Gluco-cerebrosides. - Head is usually glucose - Generally present in all non-neuronal cells ## 2. Gangliosides - Ceramides + branched oligosaccharides - With one or more Sialic Acid in addition to sugars. - Nuraminic Acid (a 9-carbon monosaccharide). Sialic Acid (Acetyl derivatives of Nuraminic Acid) - Gangliosides are found primarily in the ganglia, gray matter of the brain, and other nervous tissues. ## Outside of cell - Sphingomyelin - Glycolipid - Phosphatidylcholine - Phosphatidylserine - Phosphatidylinositol - Cytosol - Phosphatidylet ## Glycosphingolipid degradation - Degradation of glycosphingolipids occurs in lysosomes after endocytosis of membrane portions - A series of acid hydrolases participate in the degradation