《有机化学》课程PPT教学课件（Organic Chemistry with Biological Applications, 3th Edition, John McMurry, 2016）Chapter 23 Biomolecules - Lipids and Their Metabolism

GNGE JOHN MCMURRY CHAPTER 23 Biomolecules:Lipids and Their Metabolism Organic Chemistry with Biological applications

CHAPTER 23 Biomolecules: Lipids and Their Metabolism

Biomolecules:Lipids and Their Metabolism Lipids are naturally occurring organic molecules isolated from organisms by extraction with nonpolar organic solvents Fats,oils,waxes,some vitamins and hormones,and most nonprotein cell-membrane components Lipids have limited solubility in water Lipids defined by their physical property (solubility)and not by their structure

Lipids are naturally occurring organic molecules isolated from organisms by extraction with nonpolar organic solvents ▪ Fats, oils, waxes, some vitamins and hormones, and most nonprotein cell-membrane components ▪ Lipids have limited solubility in water ▪ Lipids defined by their physical property (solubility) and not by their structure Biomolecules: Lipids and Their Metabolism

Biomolecules:Lipids and Their Metabolism Lipids classified into two broad types: 1.Those that contain ester linkages that can be hydrolyzed Include fats and waxes 2.Steroids which do not have ester linkages and cannot be hydrolyzed Includes cholesterol and other steroidal hormones 0 CH2O-C-R CH3 CHO-C-R HO CH20-&-R Animal fat-a triester Cholesterol (R,R',R"=C11-C19 chains) LmigA Rpt Rd

Lipids classified into two broad types: 1. Those that contain ester linkages that can be hydrolyzed ▪ Include fats and waxes 2. Steroids which do not have ester linkages and cannot be hydrolyzed ▪ Includes cholesterol and other steroidal hormones Biomolecules: Lipids and Their Metabolism

23-1 Waxes,Fats,and Oils Waxes are mixtures of esters of long-chain carboxylic acids with long-chain alcohols Carboxylic acid usually has an even number of carbons from 24 through 36 Beeswax is the ester of the C30 alcohol triacontan-1-ol and the C16 acid hexadecanoic acid CH3(CH2)14CO(CH2)2gCH3 Triacontyl hexadecanoate(from beeswax) Cengage Leaming.All Rights Reserved

Waxes are mixtures of esters of long-chain carboxylic acids with long-chain alcohols ▪ Carboxylic acid usually has an even number of carbons from 24 through 36 ▪ Beeswax is the ester of the C30 alcohol triacontan-1-ol and the C16 acid hexadecanoic acid 23-1 Waxes, Fats, and Oils

Waxes,Fats,and Oils Animal fats and vegetable oils are the most widely occurring lipids Closely related structures Have different appearances Animal fats are solids like butter and lard Vegetable oils are liquids like corn and peanut oil

Animal fats and vegetable oils are the most widely occurring lipids ▪ Closely related structures ▪ Have different appearances ▪ Animal fats are solids like butter and lard ▪ Vegetable oils are liquids like corn and peanut oil Waxes, Fats, and Oils

Waxes,Fats,and Oils Fats and oils are triglycerides,or triacylglycerols Triesters of glycerol with three long-chain carboxylic acids called fatty acids Fats are used by animals for long-term energy storage Less highly oxidized than carbohydrates Provide about six times as much energy as an equal weight of glycogen Fatty acyl Glycerol 0 Stearoyl (stearic acid) CH2OCCH2CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2CH3 0 Oleoyl (oleic acid) CHOCCH2CH2CH2CH2CH2CH2CH2CH=CHCH2CH2CH2CH2CH2CH2CH2CH3 Linoleoyl (linoleic acid) CH2OCCH2CH2CH2CH2CH2CH2CH2CH-CHCH2CH-CHCH2CH2CH2CH2CH3 A triacylglycerol

▪ Fats and oils are triglycerides, or triacylglycerols ▪ Triesters of glycerol with three long-chain carboxylic acids called fatty acids ▪ Fats are used by animals for long-term energy storage ▪ Less highly oxidized than carbohydrates ▪ Provide about six times as much energy as an equal weight of glycogen Waxes, Fats, and Oils

Waxes,Fats,and Oils Hydrolysis of a fat or oil with aqueous NaOH yields glycerol and three fatty acids Fatty acids are generally unbranched and contain an even number of carbon atoms between 12 and 20 If double bonds are present they are generally Z,or cis -The three fatty acids of a specific triacylglycerol do not need to be the same A fat or oil is likely to be a complex mixture of many different triacyglycerols

Hydrolysis of a fat or oil with aqueous NaOH yields glycerol and three fatty acids ▪ Fatty acids are generally unbranched and contain an even number of carbon atoms between 12 and 20 ▪ If double bonds are present they are generally Z, or cis ▪ The three fatty acids of a specific triacylglycerol do not need to be the same ▪ A fat or oil is likely to be a complex mixture of many different triacyglycerols Waxes, Fats, and Oils

Waxes,Fats,and Oils Structures of some common fatty acids TABLE 23.1 Structures of Some Common Fatty Acids No.of Melting Name carbons point (C) Structure Saturated Lauric 12 43.2 CH3(CH2)10CO2H Myristic 14 53.9 CH3(CH2)12CO2H Palmitic 16 63.1 CH3(CH2)14CO2H Stearic 18 68.8 CH3(CH2)16CO2H Arachidic 20 76.5 CH3(CH2)18CO2H Unsaturated Palmitoleic 16 -0.1 (Z)-CH3(CH2)sCH-CH(CH2)7CO2H Oleic 18 13.4 (Z)-CH3(CH2)7CH-CH(CH2)7CO2H Linoleic 18 -12 (Z,Z)-CH3(CH2)4(CH-CHCH2)2(CH2)6CO2H Linolenic 18 -11 (all Z)-CH3CH2(CH-CHCH2)3(CH2)6CO2H Arachidonic 20 -49.5 (all Z)-CH3(CH2)4(CH-CHCH2)4CH2CH2CO2H

Structures of some common fatty acids Waxes, Fats, and Oils

Waxes,Fats,and Oils Composition of some fats and oils TABLE232 Composition of Some Fats and Oils Unsaturated fatty Saturated fatty acids(%) acids(%) C12 C14 C16 C18 C18 C18 Source Lauric Myristic Palmitic Stearic Oleic Linoleic Animal fat Lard 25 15 50 可 Butter 2 10 25 10 25 6 Human fat 1 3 25 8 46 10 Whale 8 12 3 35 10 blubber Vegetable oil Coconut 50 18 8 2 6 1 Corn 10 4 35 45 Olive 7 5 5 80 2 Peanut 7 5 60 20

Composition of some fats and oils Waxes, Fats, and Oils

Waxes,Fats,and Oils Palmitic acid (C6) and stearic acid (C1s)are the most abundant saturated fatty CH3CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2COH acids Stearic acid Omega-3 double bond Oleic and linoleic acids (both Cis) are the most abundant unsaturated fatty acids CH3CH2CH=CHCH2CH-CHCH2CH-CHCH2CH2CH2CH2CH2CH2CH2COH Linolenic acid,an omega-3 polyunsaturated fatty acid

Palmitic acid (C16) and stearic acid (C18) are the most abundant saturated fatty acids Oleic and linoleic acids (both C18) are the most abundant unsaturated fatty acids Waxes, Fats, and Oils