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Lipids © 1 Lipids Organic compounds present in living organisms, insoluble in water but able to be extracted by organic solvents such as: chloroform, acetone, benzene. Extraction = the process of obtaining something from a mixture or compound by chemical or physical or mechanical means © 2 Biologic role of lipids As a building material for all membrane-like structures in cells (phospholipids, cholesterol, glycolipids). Have decisive role in dynamic processes of cell membrane. Influence on fluidity, asymmetry, permeability, enzymatic activity and receptor properties (fosfolipids, cholesterol, fatty acid). Steroid hormon precursor (cholesterol) and tissues hormons (fatty acids). Take part in immunological phenomena (eikozanoids) [eicosanoids are signaling molecules made by oxidation of twentycarbon essential fatty acids] © 3 Lipids categories (according to Bloor) I. Simple lipids: esters of fatty acids with various alcohols a. Fats: esters of fatty acids with glycerol b. Waxes: esters of fatty acids with higher molecular weight monohydric alcohols c. Sterols II. Complex lipids : esters of fatty acids containing groups in addition to alcohol and fatty acids. a. Phospholipids b. Glycolipids c. Other complex lipids III. Precursor and derived lipids © 4 Lipids categories (according to Bloor) III. Precursors and lipids derivatives a) b) c) d) e) f) g) © fatty acids, glycerol, alcohols different than glycerol sterols, carbohydrates vitamins soluble in fats hormons 5 FATTY ACIDS STRUCTURES AND PROPERTIES Monocarboxylic acids with hydrocarbon chains with different amount of carbon atoms: 4 to 30. Depends on carbon quantities they have different name: 1. Short-chain (<6 atoms C) fatty acids 2. Average- chain (8 – 14 atoms C) fatty acids 3. Long-chain (> 16 atoms C) fatty acids • • Hydrocarbon chain of fatty acid is hydrophobic. Carboxylic group of fatty acids is hydrophilic. CH3(CH2)7CH=CH(CH2)7COOH Oleic acid (unsaturated) © CH3(CH2)16COOH Stearic acid (saturated) 6 FATTY ACIDS FUNCTIONALITY Reserve (store) role in adipocyts – (cell which stores synthesized fats) Structural role in membrane cells Take place in covalent modification of proteins In protein – play role as a hydrophobic anchor Energy material Derivatives of 20-carbon atoms acids are hormones. © 7 FATTY ACIDS STRUCTURE and PROPERTIES Saturated fatty acids contain over 10 carbon atoms in chain. are solids are insoluble in water melting point increases with length of the chain Unsaturated fatty acids in room temperature are usually liquids. Fatty acid’s salts with alkali metals are well soluble in water but magnesium and calcium salts are almost insoluble. © 8 FATTY ACIDS STRUCTURE and PROPERTIES Characteristic reactions of unsaturated fatty acids: Hydration: – CH = CH – + H2O – CH(OH) – CH2 – Reduction: – CH = CH – + XH2 reduction – CH2CH2 – + X Oxidation: oxidation R1 – CH = CH –R2 © R1 – CHO + R2 – CHO 9 FATTY ACIDS STRUCTURE and PROPERTIES Presence of unsaturated, double bond allows unsaturated fatty acids to posses two stereo-isomeric structures : cis and trans Oleic acid Elaidic acid 6 © 10 FATTY ACIDS Nomenclature • Common names have their names from the place where they were discovered or where they can be found • Systematic names are from Greek numbers with following endings: - anoic for saturated acids - enoic for unsaturated acids Octadecanoic acid Stearic acid © 9,12 octadecadienoic acid Linoleic acid 11 FATTY ACIDS Nomenclature • Systematic names are from Greek numbers • Location of unsaturated, double bond are indicated by ∆ (delta)) follow by the number of carbon atom with double bond . Νumber of carbon atoms participating in double bonds are counted starting from carbon atom in carboxylic group. Letters n lub ω indicate double bond location, starting from the methyl group. ω Fatty acid with cis ∆-9 bond CH3 © 12 UNSATURATED FATTY ACIDS Common name © Systematic name Abbreviated name Chemical structure Oleic 9 – octadecenoic 18:1 ∆ 9 18:1 (n-9) CH3(CH2)7CH=CH(CH2)7COOH Eikoseic 9 - eicosenoic 20:1 ∆ 9 CH3(CH2)9CH=CH(CH2)7COOH Erucic 13 doeicosenoic 22:1 ∆ 13 CH3(CH2)7CH=CH(CH2)11COO H Linoleic 9,12 octadecadienoic 18:2 ∆ 9,12 18:2 (n-6) CH3(CH2)4(CH=CHCH2)2(CH2)6 COOH Linolenic 9,12,15 octadecatrienoic 18:3 ∆ 9,12,15, 18:3 (n-3) CH3CH2(CH=CHCH2)3 (CH2)6 COOH Arachidonic 5,8,11,14 eikosanoic 20:4 ∆ 5,8,11,14, 20:4 (n-6) CH3(CH2)4(CH=CHCH2)4 (CH2)2 COOH 13 FATTY ACIDS NECESSARY UNSATURATED FATTY ACIDS There are 3 “families” of these acids: omega-3, omega-6 and omega-9 Human organism is able to place double bond only in position 9 counting from methyl group. Precursor of omega acids with bonds between position 3 and 6 must be delivered to organism with food. Source of unsaturated fatty acids : - vegetable oils, soy, corn oil - animal phospholipids Polyunsaturated fatty acids from omega family, with 5 and 6 double bonds are in large quantities in fish oils. © 14 ACYLGLYCEROLS Because of their chemical structure they belong to esters of glycerol and fatty acids Alcohol component– glycerol Acid component – monocarboxylic higher fatty acids Most often they are mixtures of triglycerols of various fatty acids. Glycerol has attached through ester bond one, two or three fatty acids. Usually, at each carbon atom from glycerol, different fatty acid is attached. © 15 Acyl Fats (acylglycerols) Glycerol H2C – OH HO – C – H H2C – OH C1 α sn-1 C2 β sn-2 C3 α sn-3 In acylglycerols secondary hydroxyl group is located on the left side of carbon atom © 16 Acyl Fats (acylglyceroles) Glycerol Triacylglycerol O H2C – OH HO – C – H H2C – OH O H2C – O – C – R1 R2 – C – O – C – H H2C – O – C – R3 O © 17 Phospholipids Phosphatidic acid Phospholipids are built from four components: Glycerol Two acyl group connected by ester bond (with C1and C2 from glycerol) Phosphate connected by ester group (with C3 from glycerol) Other alcohol (choline, ethanoloamine, serine, glycerol), connected with -OH group from phosphate © 18 Phospholipids + ) Phosphatidic acid + HO – CH2 – CH2 – N(CH 3 3 (choline) R` - palmitic acid R” – oleic acid Phosphatidylcholine (lecithin) Phosphatidic acid + ethanolamine Phosphatidylethanolamine © 19 Sphingophospholipids • Sfingophospholipids are long chain amids of fatty acids and sphingosine which additionally are containing choline. • Are composed from: sphingosine – long chain,monosaturated dihydroxyl aminoalcohol © long chain fatty acid phosphate Choline 20 Sphingophospholipids sphingosine + unsaturated fatty acid ceramide (N- acylsphingosine) + choline + H3PO4 Sphingomyelin ( good isolator for nerve tissues) © 21 Glycolipids Contain: ceramide sugar molecule (one or more) galactosylceramide glucosylceramide (cerebroside) © 22 Gangliosides Glucosylceramide derivative containing one or several groups of sialic acid (amphipatic) Sialic acid Ganglioside GM1 There are different from cerebroside that instead of monosugar they contain oligosaccharide. © 23 Isoprenoids, steroids and derivatives © 24 http://www.iupac.org/didac/ © 25 isopren (2-methyl-1,3 butadien) Isopentenyl pyrophosphate (IPP) © 3,3-dimethylallyl pyrophosphate 26 Cholesterol • cholesterol belongs to steroids and contains 6 isoprene units • It’s precursor of all steroid hormones • Component of cells and membranes © 27 Synthesis of cholesterol squalene lanosterol © sterane cholesterol 28 Cholesterol Exists in all membrane’s cells in mammalia: • • • • © In estrified form In a free form It is 10% -15% of dry weight of brain It is substrate for hormone synthesis 29 Sterane Structure: C A D B cyklopenthanperhydrophenantrene three rings of cyklohexane and one ring of cyklopenthane= 4 rings Component of: cholesterol steroid hormones bile acids © 30 Sterane structure 5- α- hydrogen trans 5-β- hydrogen cis Hydrogen bond at C5 © 31 Sterane structure 5- α- hydrogen © 5-β- hydrogen 32 Bile acids Are synthesized from cholesterol in the liver Insuficient amount of vit. C can disturb synthesis of bile acid which can leads to vein’s sclerosis Contain 1 to 3 hydroxyl groups attached to the ring Contain carboxyl group in side chain Are amphipatic (hydrophilic and hydrophobic) Can decrease surface tension of water They are good emulsifier © 33 Cholic acid (bile acid) © 34 The End 35