Lipid Chemistry Lecture (4 & 5) PDF

Title: lecture (4&5) Lipid Chemistry Present By: Prof.Ingy Badawy  ‫رؤية كلية التكنولوجيا الحيوية‬ ‫أن تكون كلية معتمدة أكاديميا ً و رائدة‬ ‫فى مجاالت التكنولوجيا الحيوية على‬ ‫المستوى المحلى واإلقليمى والدولى‬  ‫رسالة كلية التكنولوجيا الحيوية‬ ‫تلتزم كلية التكنولوجيا الحيوية...

Title: lecture (4&5) Lipid Chemistry Present By: Prof.Ingy Badawy  ‫رؤية كلية التكنولوجيا الحيوية‬ ‫أن تكون كلية معتمدة أكاديميا ً و رائدة‬ ‫فى مجاالت التكنولوجيا الحيوية على‬ ‫المستوى المحلى واإلقليمى والدولى‬  ‫رسالة كلية التكنولوجيا الحيوية‬ ‫تلتزم كلية التكنولوجيا الحيوية ‪ -‬جامعة مصر للعلوم‬ ‫والتكنولوجيا الخاصة بتخريج اخصائى تكنولوجيا حيوية‬ ‫طبقا ً للمعايير األكاديمية القياسية المعتمدة يلبى احتياجات‬ ‫سوق العمل المحلى واإلقليمى فى القطاعات الطبية‬ ‫والصيدلية و الزراعية و البيئية وإجراء بحوث علمية‬ ‫مبتكرة وتقديم خدمات مجتمعية واستشارات علمية فى إطار‬ ‫قيم إرتقائية‪.‬‬ ILOs: Recognize and describe structure, properties and metabolism of the major classes of biochemical compounds including carbohydrates, lipids and proteins. Demonstrate a systematic understanding of the processes and mechanisms of life, from molecules to cells Outlines 1. Lipid classification 2. Fatty acids 3. Eicosanoids 4. Simple lipids 5. Complex lipids 6. Derived lipids Lipids Lipids Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings 6 Lipids Lipids are Biomolecules that contain fatty acids or a steroid nucleus. Soluble in organic solvents but not in water. Named for the Greek word lipos, which means “fat.” Extracted from cells using organic solvents. 7 Types of Lipids The types of lipids containing fatty acids are Waxes. Fats and oils (triacylglycerols). Glycerophospholipids. Prostaglandins. Not steroids, as they do not contain fatty acids. 8 Structures of Lipids Copyright © 2007 by Pearson Education, Inc. 9 Publishing as Benjamin Cummings 15.2 Fatty Acids Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings 10 Fatty Acids Fatty acids Are long-chain carboxylic acids. Typically contain 12-18 carbon atoms. Are insoluble in water. Can be saturated or unsaturated. Copyright © 2007 by Pearson Education, Inc. 11 Publishing as Benjamin Cummings Fatty Acid Formulas The formulas for fatty acids are written as Condensed formulas. Line-bond formulas. For example caprylic acid with 8 carbon atoms. CH3—(CH2)6—COOH CH3—CH2—CH2—CH2—CH2—CH2—CH2—COOH O OH 12 Saturated Fatty Acids Saturated fatty acids have Single C–C bonds. Molecules that fit closely together in a regular pattern. Strong attractions between fatty acid chains. High melting points that make them solids at room temperature. Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings 13 Some Saturated Fatty Acids Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings 14 Unsaturated Fatty Acids Unsaturated fatty acids Have one or more double C=C bond Typically contain cis double bonds. Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings 15 Properties of Unsaturated Fatty Acids Unsaturated fatty acids “kinks” in chain Have “kinks” in the fatty acid chains. Do not pack closely. Have few attractions between chains. Have low melting points. Are liquids at room temperature. Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings 16 Unsaturated Fatty Acids Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings 17 Comparing Melting Points of Some Fatty Acids Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings 18 Learning Check Assign the melting points of –17°C, 13°C, and 69°C to the correct fatty acid. Explain. stearic acid (18 C) saturated oleic acid (18 C) one double bond linoleic acid (18 C) two double bonds 19 Solution Stearic acid is saturated and would have a higher melting point than the unsaturated fatty acids. Because linoleic has two double bonds, it would have a lower mp than oleic acid, which has one double bond. stearic acid mp 69°C saturated oleic acid mp 13°C linoleic acid mp -17°C most unsaturated 20 Prostaglandins Prostaglandins have 20 carbon atoms in their fatty acid chains. An OH on carbon 11 and 15. A trans double bond at carbon 13. C 11 C 13 C 15 Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings 21 Prostaglandins in the Body Prostaglandins are Produced by injured tissues. Involved in pain, fever, and inflammation. Not produced when anti-inflammatory drugs such as aspirin inhibit their synthesis. Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings 22 Omega-6 and Omega 3- Fatty Acids Fatty acids ▪ In vegetable oils are mostly omega-6 with the first C=C at C6. linoleic acid CH3─(CH2)4─CH=CH─CH2─CH=CH─(CH2)7─COOH 6 ▪ In fish oils are mostly omega-3 with the first C=C at C3. linolenic acid CH3─CH2─(CH=CH─CH2)3─(CH2)6─COOH 3 Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings 23 Some Omega-6 and Omega-3 Fatty Acids 24 Learning Check Write a fatty acid with 10 carbon atoms that is: A. saturated B. monounsaturated omega-3 C. monounsaturated omega-6 25 Solution Write a fatty acid with 10 carbon atoms that is: A. saturated CH3—CH2—CH2—CH2—CH2—CH2—CH2—CH2—CH2—COOH B. monounsaturated omega-3 CH3—CH2—CH=CH—CH2—CH2—CH2—CH2—CH2—COOH C. monounsaturated omega-6 CH3—CH2—CH2—CH2—CH2—CH=CH—CH2—CH2—COOH 26 Waxes, Fats, and Oils Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings 27 Waxes Waxes are Esters of saturated fatty acids and long-chain alcohols. Coatings that prevent loss of water by leaves of TABLE 17.2 plants. Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings 28 Fats and Oils: Triacylglycerols Fats and oils are Also called triacylglycerols. Esters of glycerol. Produced by esterification. Formed when the hydroxyl groups of glycerol react with the carboxyl groups of fatty acids. Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings 29 Triacylglycerols In a triacylglycerol, Glycerol forms ester bonds with three fatty acids. Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings 30 Formation of a Triacylglycerol glycerol + three fatty acids triacylglycerol O CH2 OH HO C (CH2)14CH3 O CH OH + HO C (CH2)14CH3 O O CH2 OH HO C (CH2)14CH3 CH2 O C (CH2)14CH3 O CH O C (CH2)14CH3 + 3H2O O CH2 O C (CH2)14CH3 31 Olive Oil Olive oil Contains a high percentage of oleic acid, which is a monounsaturated fatty acid with one cis double bond. Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings 32 Learning Check What are the fatty acids in the following triacylglycerol? O CH2 O C (CH2)16CH3 O CH O C (CH2)7CH CH(CH2)7CH3 O CH2 O C (CH2)12CH3 33 Solution O CH2 O C (CH2)16CH3 Stearic acid O CH O C (CH2)7CH CH(CH2)7CH3 Oleic acid O CH2 O C (CH2)12CH3 Myristic acid 34 Melting Points of Fats and Oils A triacylglycerol that is a fat Is solid at room temperature. Is prevalent in meats, whole milk, butter, and cheese. A triacylglycerol that is an oil Is liquid at room temperature. Is prevalent in plants such as olive and safflower. 35 Oils with Unsaturated Fatty Acids Oils Have more unsaturated fats. Have cis double bonds that cause “kinks” in the fatty acid chains. Cannot pack triacylglycerol molecules as close together as in fats. Have lower melting points than saturated fats. Are liquids at room temperature. 36 Diagram of Triacylglycerol with Unsaturated Fatty Acids Unsaturated fatty acid chains have kinks that do not allow close packing. Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings 37 Saturated and Unsaturated Fatty Acids In Fats and Oils Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings 38 Chemical Properties of Triacylglycerols Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings 39 Chemical Properties of Triacylglycerols The chemical reactions of triacylglycerols are similar to those of alkenes and esters. In hydrogenation, double bonds in unsaturated fatty acids react with H2 in the presence of a Ni or Pt catalyst. In hydrolysis, ester bonds are split by water in the presence of an acid, a base, or an enzyme. 40 Hydrogenation of Oils The hydrogenation of oils Adds hydrogen (H2) to the carbon atoms of double bonds. Converts double bonds to single bonds. Increases the melting point. Produces solids such as margarine and shortening. 41 Copyright © 2007 by Pearson Education, Inc Publishing as Benjamin Cummings Hydrogenation O CH2 O C (CH2)5CH CH(CH2)7CH3 O Ni CH O C (CH2)5CH CH(CH2)7CH3 + 3H2 O O CH2 O C (CH2)5CH CH(CH2)7CH3 CH2 O C (CH2)14CH3 O glyceryl tripalmitoleate CH O C (CH2)14CH3 (tripalmitolean) O CH2 O C (CH ) CH glyceryl tripalmitate 2 14 3 (tripalmitin) 42 Learning Check What product(s) is obtained from the complete hydrogenation of glyceryl trioleate? 1. Glycerol and 3 oleic acids 2. Glyceryltristearate 3. Glycerol and 3 stearic acids 43 Solution What product(s) is obtained from the complete hydrogenation of glyceryl trioleate? 2. Glyceryltristearate 44 Olestra, A Fat Substitute Olestra is Used in foods as an artificial fat. Sucrose linked by ester bonds to several long- chain fatty chains. Not broken down in the intestinal tract. Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings 45 Cis and Trans Fatty Acids Unsaturated fatty acids can be Cis with bulky groups on same side of C=C. CH3─ (CH2)5 (CH2)7─ COOH cis C=C H H Trans have bulky groups on opposite sides of C=C. CH3─ (CH2)5 H C=C trans H (CH2)7─ COOH 46 Trans Fatty Acids and Hydrogenation Trans fatty acids Are formed during hydrogenation when cis double bonds are converted to trans double bonds. In the body behave like saturated fatty acids. Are estimated to make up 2-4% of our total Calories. Are reported in several studies reported to raise LDL-cholesterol and lower HDL-cholesterol. 47 Learning Check (1) True or (2) False A. There are more unsaturated fats in vegetable oils. B. Vegetable oils have higher melting points than fats. C. Hydrogenation of oils converts some cis-double bonds to trans- double bonds. D. Animal fats have more saturated fats. 48 Solution (1) True or (2) False A. T There are more unsaturated fats in vegetable oils. B. F Vegetable oils have higher melting points than fats. C. T Hydrogenation of oils converts some cis-double bonds to trans- double bonds. D. T Animal fats have more saturated fats. 49 Hydrolysis In hydrolysis, Triacylglycerols split into glycerol and three fatty acids. An acid or enzyme catalyst is required. O CH2 O C (CH2)14CH3 O H+ CH O C (CH2)14CH3 +3H2O O CH2 O C (CH2)14CH3 CH2 OH O CH OH + 3 HO C (CH2)14CH3 CH2 OH 50 Saponification and Soap Saponification Is the reaction of a fat with a strong base. Splits triacylglycerols into glycerol and the salts of fatty acids. Is the process of forming “soaps” (salts of fatty acids). With KOH gives softer soaps. 51 Saponification O CH2 O C (CH2)14CH3 O CH O C (CH2)14CH3 + 3NaOH O CH2 OH CH2 O C (CH2)14CH3 CH OH O + 3 Na+ -O C (CH2)14CH3 CH2 OH “soap” 52 Learning Check What products are obtained from the complete hydrolysis of glyceryl trioleate? 1. Glycerol and 3 oleic acids 2. Glyceryl tristearate 3. Glycerol and 3 stearic acids 53 Solution What products are obtained from the complete hydrolysis of glyceryl trioleate? 1. Glycerol and 3 oleic acids 54 Learning Check Write the product of the following reaction. O CH2 O C (CH2)5CH CH(CH2)7CH3 O Ni CH O C (CH2)5CH CH(CH2)7CH3 + 3 H2 O CH2 O C (CH2)5CH CH(CH2)7CH3 55 Solution O CH2 O C (CH2)14CH3 O CH O C (CH2)14CH3 O CH2 O C (CH2)14CH3 56 Glycerophospholipids Glycerophospholipids are The most abundant lipids in cell membranes. Composed of glycerol, two fatty acids, phosphate and an amino alcohol. Fatty acid Fatty acid Glycerol Amino PO4 alcohol 57 Glycerophospholipids Are Polar A glycerophospholipid has Two nonpolar fatty acid chains. A phosphate group and a polar amino alcohol. CH3 │+ + HO−CH2−CH2−N−CH3 HO−CH2−CH2−NH3 │ choline CH3 ethanolamine + NH3 │ Amino alcohols HO−CH2−CH−COO− serine 58 Structure and Polarity of A Glycerophospholipid Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings 59 Lecithin and Cephalin Lecithin and cephalin are glycerophospholipids Abundant in brain and nerve tissues. Found in egg yolk, wheat germ, and yeast. Copyright © 2007 by Pearson Education, Inc Publishing as Benjamin Cummings 60 Learning Check Identify each as a A. fatty acid B. triacylglycerol C. amino alcohol D. glycerophospholipid 1. glyceryl trioleate 2. cephalin 3. choline 4. palmitic acid 61 Solution Identify each as a A. fatty acid B. triacylglycerol C. amino alcohol D. glycerophospholipid 1. glyceryl trioleate B. triacylglycerol 2. cephalin D. glycerophospholipid 3. choline C. amino alcohol 4. palmitic acid A. fatty acid 62 Learning Check Identify the components and type of glycerophospholipid O ║ CH2−O −C −(CH2)16 −CH3 O ║ CH2−O −C −(CH2)16 −CH3 + O NH3 ║ │ CH2−O −P −O − CH2−CH−COO- │ O- 63 Solution Identify the components and type of glycerophospholipid O ║ CH2−O −C −(CH2)16 −CH3 O 2 stearic acids ║ CH2−O −C −(CH2)16 −CH3 + O NH3 ║ │ type = cephalin CH2−O −P −O − CH2−CH−COO- │ serine O- phosphate amino alcohol 64 Sphingolipids Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings 65 Sphingolipids Sphingolipids Are similar to phospholipids. Contain sphingosine (a long-chain amino alcohol), a fatty acid, phosphate, and a small amino alcohol. Have polar and nonpolar regions. fatty acid sphingosine amino PO4 alcohol 66 Sphingosine Sphingosine is a long-chain unsaturated amino alcohol. CH3−(CH2)12 −CH=CH−CH−OH │ CH−NH2 │ CH2−OH sphingosine 67 Sphingolipids In sphingomyelin, a sphingolipid found in nerve cells There is an amide bond between a fatty acid and sphingosine, an 18-carbon alcohol. Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings 68 Glycosphingolipids Glycosphingolipids contain monosaccharides bonded to the –OH of sphingosine by a glycosidic bond. Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings 69 Glycosphingolipids and Cerebrosides Glycosphingolipids Are sphingolipids that contain monosaccharides. Can be a cerebroside with galactose. Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings 70 Gangliosides Gangliosides Are similar to cerebrosides, but contain two or more monosaccharides. Are important in neurons. Act as receptor for hormones and viruses. Can accumulate and cause genetic diseases. 71 Gangliosides GM2 is a ganglioside That accumulates in Tay-Sachs disease. Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings 72 Lipid Diseases (Lipidoses) In many lipid diseases, the deficiency of an enzyme causes the accumulation of glycolipids. TABLE 17.3 Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings 73 Learning Check Identify each as a 1) Fatty acid 2) Triacylglycerol 3) Amino alcohol 4) Glycerophospholipid 5) Glycosphingolipid A. Glyceryl trioleate B. Cephalin C. Choline D. Galactocerebroside E. Palmitic acid 74 Solution A. Glyceryl trioleate 2) Triacylglycerol B. Cephalin 4) Glycerophospholipid C. Choline 3) Amino alcohol D. Galactocerebroside 5) Glycosphingolipid E. Palmitic acid 1) Fatty acid 75 Steroids: Cholesterol, Bile Salts, and Steroid Hormones CH3 CH3 CH3 CH3 CH3 HO Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings 76 Steroid Nucleus A steroid nucleus consists of 3 cyclohexane rings. 1 cyclopentane ring. No fatty acids. steroid nucleus 77 Cholesterol Cholesterol Is the most abundant steroid in the body. Has methyl CH3- groups, alkyl chain, and -OH attached to the steroid nucleus. CH3 CH3 CH3 CH3 CH3 HO 78 Cholesterol in the Body A normal, open artery. Cholesterol in the body Is obtained from meats, milk, and eggs. Is synthesized in the liver. Is needed for cell membranes, brain and nerve tissue, steroid hormones, and Vitamin D. Clogs arteries when high levels form plaque. An artery clogged by cholesterol plaque Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings 79 Cholesterol in Foods Cholesterol is TABLE 17.4 Synthesized in the liver. Obtained from foods. Considered elevated if plasma cholesterol exceeds 200 mg/dL. Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings 80 Learning Check Match the components of the cholesterol molecule with the following: ___ carbon chain ___hydroxyl group ___ steroid nucleus D ___methyl group CH3 CH3 CH3 B CH3 CH3 A C HO 81 Solution Match the components of the cholesterol molecule with the following: D carbon chain A hydroxyl group C steroid nucleus B methyl group D CH3 CH3 CH3 B CH3 CH3 A C HO 82 Bile Salts Bile salts Are synthesized in the liver from cholesterol. Are stored in the gallbladder. Are secreted into the small intestine. Have a polar and a nonpolar region Mix with fats to break them part. Emulsify fat particles to provide large surface area. 83 Bile Salts cholic acid, a bile acid glycine, an amino acid O CH3 CH2 OH C N COO- Na+ CH3 H Polar region CH3 HO OH Nonpolar region sodium glycocholate, a bile salt 84 Lipoproteins Lipoproteins Combine lipids with proteins and phospholipids. Are soluble in water because the surface consists of polar lipids. 85 Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings Types of Lipoproteins Lipoproteins Differ in density, composition, and function. Include low-density lipoprotein (LDLs) and high- density lipoprotein (HDLs). TABLE 17.5 Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings 86  Transport of Lipoproteins in the Body Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings 87 Steroid Hormones Steroid hormones Are chemical messengers in cells. Are produced from cholesterol. Include sex hormones such as androgens (testosterone) in males and estrogens (estradiol) in females. 88 Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings Adrenal Corticosteroids Adrenal corticosteroids are steroid hormones that Are produced by the adrenal glands located on the top of each kidney. Include aldosterone, which regulates electrolytes and water balance by the kidneys. Include cortisone, a glucocorticoid, which increases blood glucose level and stimulates the synthesis of glycogen in the liver. 89 Adrenal Corticosteroids Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings 90 Anabolic Steroids Anabolic steroids Are derivatives of testosterone. Are used illegally to increase muscle mass. Have side effects including fluid retention, hair growth, sleep disturbance, and liver damage. 91 Learning Check Identify each as a 1. fatty acid 2. steroid 3. triacylglycerol 4. phospholipid 5. sphingolipid A. cholesterol B. glycerol, 2 fatty acids, phosphate, and choline C. glyceryl tristearate D. sphingosine, fatty acid, phosphate, and choline E. estradiol F. bile salts G. lipids in plasma membranes 92 Solution A. cholesterol 2 steroid B. glycerol, 2 fatty acids, phosphate, and choline 4 phospholipid C. glyceryl tristearate 3 triacylglycerol D. sphingosine, fatty acid, phosphate, and choline 5 sphingolipid E. estradiol 2 steroid F. bile salts 2 steroid G. lipids in plasma membranes 4 phospholipid, 5 sphingolipid. 93  Cell Membranes Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings 94 Cell Membranes Cell membranes Separate cellular contents from the external environment. Consist of a lipid bilayer made of two rows of phospholipids. Have an inner portion made of the nonpolar tails of phospholipids with the polar heads at the outer and inner surfaces. 95 Fluid Mosaic Model of Cell Membranes The lipid bilayer Contains proteins, carbohydrates, and cholesterol. Has unsaturated fatty acids that make cell membranes fluid-like rather than rigid. Has proteins and carbohydrates on the surface that communicate with hormones and neurotransmitters. 96 Fluid Mosaic Model Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings 97 Transport Through Cell Membranes The transport of substances through cell Membranes involves Diffusion (passive transport), which moves particles from a higher to a lower concentration. Facilitated transport, which uses protein channels to increase the rate of diffusion. Active transport, which moves ions against a concentration gradient. 98 Transport Pathways Through Cell Membranes Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings 99 Learning Check The transport of particles across a cell membrane from high concentration to low concentration is called 1. Facilitated transport 2. Diffusion 3. Active transport 100 Solution The transport of particles across a cell membrane from high concentration to low concentration is called 2. Diffusion 101