19-1 chemistry 121 winter 2009 la tech chapter 19. lipids sections

19-1Chemistry 121 Winter 2009 LA Tech

Chapter 19. LipidsChapter 19. Lipids

SectionsSections


Chapter 19Chapter 19

19.1 Structure and Classification of Lipids19.1 Structure and Classification of Lipids19.2 Fatty Acids: Lipid Building Blocks19.2 Fatty Acids: Lipid Building Blocks19.3 Physical Properties of Fatty Acids19.3 Physical Properties of Fatty Acids19.4 Energy-Storage Lipids: Triacylglycerols19.4 Energy-Storage Lipids: Triacylglycerols19.5 Dietary Considerations and Triacylglycerols19.5 Dietary Considerations and Triacylglycerols19.6 Chemical Reactions of Triacylglycerols19.6 Chemical Reactions of Triacylglycerols19.7 Membrane Lipids: Phospholipids19.7 Membrane Lipids: Phospholipids19.8 Membrane Lipids: Sphingoglycolipids19.8 Membrane Lipids: Sphingoglycolipids19.9 Membrane Lipids: Cholesterol19.9 Membrane Lipids: Cholesterol19.10 Cell Membranes19.10 Cell Membranes19.11 Emulsification Lipids: Bile Acids19.11 Emulsification Lipids: Bile Acids19.12 Messenger Lipids: Steroid Hormones19.12 Messenger Lipids: Steroid Hormones19.13 Messenger Lipids: Eicosanoids19.13 Messenger Lipids: Eicosanoids19.14 Protective-Coating Lipids: Biological Waxes19.14 Protective-Coating Lipids: Biological WaxesChemistry at a Glance: Types of Lipids and How They FunctionChemistry at a Glance: Types of Lipids and How They FunctionChemical Connections: The Fat Content of Tree Nuts and Peanuts; Chemical Connections: The Fat Content of Tree Nuts and Peanuts; Artificial Fat Substitutes; The Cleansing Action of Soap; Trans Fatty Acids Artificial Fat Substitutes; The Cleansing Action of Soap; Trans Fatty Acids and Blood Cholesterol Levels; Steroid Drugs in Sports; The Mode of and Blood Cholesterol Levels; Steroid Drugs in Sports; The Mode of Action for Anti-Inflammatory DrugsAction for Anti-Inflammatory Drugs


LipidsLipids A heterogeneous class of naturally occurring A heterogeneous class of naturally occurring

organic compounds classified together on the organic compounds classified together on the basis of common solubility propertiesbasis of common solubility properties• insoluble in water• soluble in aprotic organic solvents including diethyl

ether, dichloromethane, and acetone

Lipids includeLipids include• Waxes• triglycerides• phospholipids • Prostaglandins• cholesterol, steroid hormones, and bile acids• fat-soluble vitamins


Structure and Classification of LipidsStructure and Classification of Lipids

Lipids that are ester or amides of fatty acids:Lipids that are ester or amides of fatty acids:WaxesWaxes – are carboxylic acid esters where both are carboxylic acid esters where both – are carboxylic acid esters where both are carboxylic acid esters where both

R groups are long straight hydrocarbon chain. R groups are long straight hydrocarbon R groups are long straight hydrocarbon chain. R groups are long straight hydrocarbon chain.chain.

Performs external protective functions. Performs external protective functions.Performs external protective functions. Performs external protective functions.

TriglyceridesTriglycerides– are carboxylic acid are carboxylic acid triesters of– are carboxylic acid are carboxylic acid triesters of

Glycerols . They are a major source of biochemical energy. Glycerols . They are a major source of biochemical energy.

Glycolipids Glycolipids – amides derived from sphingosine, contain polar carbohydrate groups. On the – amides derived from sphingosine, contain polar carbohydrate groups. On the cell surface, they connect with intracellular messengers. cell surface, they connect with intracellular messengers.

Glycerophopholipids –Glycerophopholipids – triesters of glycerols that contain charged phosphate diesters. They triesters of glycerols that contain charged phosphate diesters. They help to control the flow of molecules into and out of cells.help to control the flow of molecules into and out of cells.

Sphingomyelins Sphingomyelins – amides derived from an amino alcohol, also contain charged amino – amides derived from an amino alcohol, also contain charged amino alcohol, alcohol,

Phosphate diester groups. They are essential to the structure of cell membranes. Phosphate diester groups. They are essential to the structure of cell membranes.

Lipids that are not esters or amides: Lipids that are not esters or amides: SteroidsSteroids – They performs various functions They performs various functions – They performs various functions They performs various functions

such as hormones and contributes to the structure of cell membranes.such as hormones and contributes to the structure of cell membranes.

Eicosanoids Eicosanoids – They are carboxylic acids that are a special type of intracellular chemical– They are carboxylic acids that are a special type of intracellular chemical

messengers.messengers.


Wax esters are fatty acids esterified to long-chain saturated or monoenoic (one double Wax esters are fatty acids esterified to long-chain saturated or monoenoic (one double bond) alcohols. bond) alcohols.

They are carboxylic acid esters where both are carboxylic acid esters where bothThey are carboxylic acid esters where both are carboxylic acid esters where both

R groups are long straight hydrocarbon chain. R groups are long straight hydrocarbon R groups are long straight hydrocarbon chain. R groups are long straight hydrocarbon chain.chain.

They performs external protective functions. Performs external protective functions.They performs external protective functions. Performs external protective functions.

BeeswaxBeeswax

Spermaciti: sperm whale waxSpermaciti: sperm whale wax

O

CH3(CH2)24 O (CH2)29CH3

O

CH3(CH2)14 O (CH2)15CH3


Bee’s wax

Spermaceti source

Carnauba wax source


TriglyceridesTriglycerides

CH2OH

CHOH

CH2OH

CH2

CH2

CH

O

O

O

O

O

O

RCOOH

Glycerol

Saturated Fat or Oil


Properties of Fats and OilsProperties of Fats and Oils

OilsOils: A mixture of triglycerides that is liquid: A mixture of triglycerides that is liquid

because it contains a high proportions of because it contains a high proportions of unsaturated unsaturated fatty acidsfatty acids. .

Fats Fats : A mixture of triglycerides that is solid because it : A mixture of triglycerides that is solid because it contains a high proportions of contains a high proportions of saturated fatty acidssaturated fatty acids..


Physical properties of TriglyceridesPhysical properties of TriglyceridesDepends on their fatty acid componentsDepends on their fatty acid components

• melting point increases as the number of carbons in their hydrocarbon chains increases and as the number of double bonds decreases

• triglycerides rich in unsaturated fatty acids are generally liquid at room temperature and are called oilsoils

• triglycerides rich in saturated fatty acids are generally semisolids or solids at room temperature and are called fatsfats


TriglyceridesTriglyceridesThe lower melting points of triglycerides rich in The lower melting points of triglycerides rich in

unsaturated fatty acids are related to differences unsaturated fatty acids are related to differences in their three-dimensional shapein their three-dimensional shape• hydrocarbon chains of saturated fatty acids can lie

parallel with strong dispersion forces between their chains; they pack into well-ordered, compact crystalline forms and melt above room temperature

• because of the cis configuration of the double bonds in unsaturated fatty acids, their hydrocarbon chains have a less ordered structure and dispersion forces between them are weaker; these triglycerides have melting points below room temperature


Reduction of TriglyceridesReduction of Triglycerides• the process of converting fats to oils is called

hardeninghardening and involves catalytic reduction of some or all of an oil’s carbon-carbon double bonds

• in practice, the process is controlled to produce a fat of a desired consistency

• the resulting fats are sold for cooking (Crisco, Spry, and others)

• margarine and other butter substitutes are produced by partial hydrogenation of polyunsaturated oils derived from corn, peanuts, and soybeans

• because catalytic hydrogenation is to some degree reversible, hardening results in the isomerization of some cis-fatty acids to trans-fatty acids; trans fatty acids are to be avoided as much as possible


TriglyceridesTriglyceridesAn ester of glycerol with three fatty acidsAn ester of glycerol with three fatty acids

CH2OCR

CH2OCR''

R'COCH

O

O

O1. NaOH, H2O

2. HCl, H2O

CH2OH

CH2OHHOCH

RCOOH

R'COOH

R''COOH 1,2,3-Propanetriol(Glycerol, glycerin)

+

Fatty acidsA triglyceride


Soaps and DetergentsSoaps and DetergentsNatural soaps are prepared by boiling lard or other Natural soaps are prepared by boiling lard or other

animal fat with NaOH, in a reaction called animal fat with NaOH, in a reaction called saponificationsaponification (Latin, (Latin, saposapo, soap), soap)

CH2OCR

CH2OCR

RCOCH O

O

O3NaOH CHOH

CH2OH

CH2OH

3RCO-Na+

O

Sodium soaps1,2,3-Propanetriol(Glycerol; glycerin)

A triglyceride

+saponification

+


Soaps and DetergentsSoaps and DetergentsSoaps clean by acting as emulsifying agentsSoaps clean by acting as emulsifying agents

• the long hydrophobic hydrocarbon chains of soaps are insoluble in water and tend to cluster in such a way as to minimize their contact with water

• the polar hydrophilic carboxylate groups tend to remain in contact with the surrounding water molecules

• driven by these two forces, soap molecules spontaneously cluster into micelles

• MicelleMicelle: a spherical arrangement of organic molecules in water clustered so that their hydrophobic parts are buried inside the sphere and their hydrophilic parts are on the surface of the sphere and in contact with water


Soaps and DetergentsSoaps and Detergents• when soap is mixed with water-insoluble grease, oil,

and fat stains, the nonpolar parts of the soap micelles “dissolve” nonpolar dirt molecules and they are carried away in the polar wash water


SoapsSoapsSoaps form water-insoluble salts when used in Soaps form water-insoluble salts when used in

water containing Ca(II), Mg(II), and Fe(III) ions water containing Ca(II), Mg(II), and Fe(III) ions ((hard waterhard water))

2CH3(CH2)14COO-Na+2CH3(CH2)14COO-Na+ Ca2+

Ca2+

[CH3(CH2)14COO-]2Ca2+2Na

++

+

A sodium soap(soluble in water as micelles)

Calcium salt of a fatty acid (insoluble in water)

+

+

A sodium soap(soluble in water as micelles)

Calcium salt of a fatty acid (insoluble in water)


Synthetic DetergentsSynthetic DetergentsThe design criteria for a good detergent areThe design criteria for a good detergent are

• a long hydrocarbon tail of 12 to 20 carbons• a polar head group that does not form insoluble salts

with Ca(II), Mg(II), or Fe(III) ions• the most widely used synthetic detergents are the

linear alkylbenzenesulfonates (LAS)

• also added to detergent preparations are foam stabilizers, bleaches, and optical brighteners

CH3(CH2)10CH2

1. H2SO4

2. NaOHCH3(CH2)10CH2 SO3

-Na

+

Dodecylbenzene Sodium 4-dodecylbenzenesulfonate(an anionic detergent)


Fatty AcidsFatty Acids A long, unbranched chain carboxylic acidA long, unbranched chain carboxylic acid

• nearly all have an even number of carbon atoms, most between 12 and 20, in an unbranched chain

• the three most abundant are palmitic acid (16:0), stearic acid (18:0), and oleic acid (18:1)

• in most unsaturated fatty acids, the cis isomer predominates; the trans isomer is rare

• unsaturated fatty acids have lower melting points than their saturated counterparts; the greater the degree of unsaturation, the lower the melting point


Fatty AcidsFatty AcidsThe most abundant fatty acids

CH3(CH2)12COOH

CH3(CH2)10COOH

CH3(CH2)14COOH

CH3(CH2)16COOH

CH3(CH2)18COOH

CH3(CH2)7CH=CH(CH2)7COOH

CH3(CH2)5CH=CH(CH2)7COOH

CH3(CH2)4(CH=CHCH2)2(CH2)6COOH

CH3CH2(CH=CHCH2)3(CH2)6COOH

CH3(CH2)4(CH=CHCH2)4(CH2)2COOH

Structure

-49

16

1

77

63stearic acid

palmitic acid

Unsaturated Fatty Acids

Saturated Fatty Acids

20:4

18:3

18:2

18:1

16:1

20:0

18:0

16:014:0

12:0

Carbon Atoms/Double Bonds

mp(°C)

Common Name

-11

-5

70

58

44

arachidonic acid

linolenic acid

linoleic acid

oleic acid

palmitoleic acid

arachidic acid

myristic acid

lauric acid


Saturated Fatty AcidsSaturated Fatty Acids


Unsaturated Fatty AicdsUnsaturated Fatty Aicds


Saturated/unsturated fatty acidsSaturated/unsturated fatty acids


Saturated/unstaureated MixturesSaturated/unstaureated Mixtures


Fatty AcidsFatty Acidsthe greater the degree of unsaturation the lower the the greater the degree of unsaturation the lower the

melting point melting point

COOH

COOH

COOH

COOH

Stearic acid (18:0)(mp 70°C)

Oleic acid (18;1)(mp 16°C)

Linoleic acid (18:2)(mp-5°C)

Linolenic acid (18:3)(mp -11°C)


What are "Omega" series fatty acids?What are "Omega" series fatty acids?

Scientists differentiate fatty acids by the Scientists differentiate fatty acids by the characteristics of their molecules. The two characteristics of their molecules. The two principal essential fatty acids are Omega-6 principal essential fatty acids are Omega-6

(n-6) series and the Omega-3(n-3) series. The (n-6) series and the Omega-3(n-3) series. The number indicates the position of the first double number indicates the position of the first double carbon bond when counting from a specified end carbon bond when counting from a specified end of the molecule. of the molecule.


Essential Fatty AcidsEssential Fatty Acids

Fatty acids that cannot be produced by the body Fatty acids that cannot be produced by the body and are necessary for proper metabolism. The and are necessary for proper metabolism. The OMEGA 6 and OMEGA 3 fatty acids are referred to OMEGA 6 and OMEGA 3 fatty acids are referred to as Essential Fatty Acids (EFA).as Essential Fatty Acids (EFA).


PhospholipidsPhospholipidsPhospholipids are the second most abundant group Phospholipids are the second most abundant group

of naturally occurring lipidsof naturally occurring lipids• they are found almost exclusively in plant and animal

membranes, which typically consist of 40% to 50% phospholipids and 50% to 60% proteins

• the most abundant phospholipids are derived from phosphatidic acid, a molecule in which glycerol is esterified with two fatty acids and one phosphoric acid

• further esterification with a low-molecular weight alcohol gives a phospholipid

• the three most abundant fatty acids in phosphatidic acids are palmitic acid (16:0), stearic acid (18:0), and oleic acid (18:1)


Phospholipids Phospholipids

Phosphate(POPhosphate(PO44 )-containing molecules with )-containing molecules with

structures related to the triglycerides are aclled structures related to the triglycerides are aclled GlycerophopholipidsGlycerophopholipids

E.g. Phosphatidycholine (lecithin)E.g. Phosphatidycholine (lecithin)


Examples of glycerophospholipidsExamples of glycerophospholipids

Name

Phosphatidyl choline (lecithin)

Phosphatidyl ethanolamine (cephalin)


PhospholipidsPhospholipidsA phosphatidate and a phospholipidA phosphatidate and a phospholipid

CH2

CHCH2

OO

O

O

O-P-O-O

O-

CH2

CHCH2-O-P-OCH2CH2N(CH3)3

OO

O

O

O-

O

A phosphatidate

A phospholipid

nonpolarhydrocarbontails polar head

groups


PhospholipidsPhospholipids


Phosphatidycholine (lecithin)Phosphatidycholine (lecithin)


PhospholipidsPhospholipids• low-molecular weight alcohols in phospholipids

NH3+

HOCH2CHCOO-

HOCH2CH2N(CH3)3

HOCH2CH2NH2

HOHO

OHOH

OHHO

Name and Formula Name of Phospholipid

ethanolamine

+cholinephosphatidylcholine(lecithin)

phosphatidylethanolamine(cephalin)

serinephosphatidylserine

inositolphosphatidylinositol


Lipid BilayerLipid BilayerWhen placed in aqueous solution, phospholipids When placed in aqueous solution, phospholipids

spontaneously form a spontaneously form a lipid bilayerlipid bilayer• polar head groups lie on the surface, giving the bilayer

an ionic coating• nonpolar fatty acid hydrocarbon chains lie buried

within the bilayer

This self-assembly is driven by two noncovalent This self-assembly is driven by two noncovalent forcesforces• hydrophobic effectshydrophobic effects, which result when nonpolar

hydrocarbon chains cluster to exclude water molecules• electrostatic interactionselectrostatic interactions, which result when polar head

groups interact with water and other polar molecules in the aqueous environment


Plasma membrane Plasma membrane Planar lipid bilayers Planar lipid bilayers

Biological membranes are bilipid layers .Biological membranes are bilipid layers .

In a real cell the membrane phospholipids create a In a real cell the membrane phospholipids create a spherical three dimensional lipid spherical three dimensional lipid bilayer shell around the cell. However, they are bilayer shell around the cell. However, they are often represented two-dimensionally as:often represented two-dimensionally as:

Passive tranport

Active transport


Biological MembranesBiological MembranesFluid mosaic modelFluid mosaic model:: a biological membrane a biological membrane

consists of a phospholipid bilayer with proteins, consists of a phospholipid bilayer with proteins, carbohydrates, and other lipids embedded on the carbohydrates, and other lipids embedded on the surface and in the bilayersurface and in the bilayer• fluidfluid signifies that the protein components of

membranes “float” in the bilayer and can move freely along the plane of the membrane

• mosaicmosaic signifies that the various components of the membrane exist side by side, as discrete units rather than combining to form new molecules and ions


Fluid-Mosaic ModelFluid-Mosaic Model


Prostaglandins Prostaglandins

Essential fatty acids in the cell membranes Essential fatty acids in the cell membranes produce prostaglandins. produce prostaglandins.

Prostaglandins regulate bodily functions in the Prostaglandins regulate bodily functions in the heart, kidneys, liver, lungs, brain, heart, kidneys, liver, lungs, brain,

nerves and the immune system. nerves and the immune system.


Types of ProstaglandinsTypes of ProstaglandinsIn human beings, there are three families of In human beings, there are three families of

prostaglandins, each of which is derived prostaglandins, each of which is derived from a different fatty acid. from a different fatty acid.

Prostaglandin PGProstaglandin PG

PGEPGE11

PGFPGF11

PGEPGE22

PGFPGF22

EicosanoidsEicosanoids

Thromboxane AThromboxane A2 2

Leukotriene BLeukotriene B4 4


ProstaglandinsProstaglandinsProstaglandinsProstaglandins: a family of compounds that have : a family of compounds that have

the 20-carbon skeleton of prostanoic acidthe 20-carbon skeleton of prostanoic acid

Prostanoic acid

192018

1716

1514

13

78

9

10

1112

65

43

21CO2H


ProstaglandinsProstaglandinsProstaglandins are not stored in tissues as such, Prostaglandins are not stored in tissues as such,

but are synthesized from membrane-bound 20-but are synthesized from membrane-bound 20-carbon polyunsaturated fatty acids in response to carbon polyunsaturated fatty acids in response to specific physiological triggersspecific physiological triggers• one such polyunsaturated fatty acid is arachidonic acid

COOH

Arachidonic acid

9 8

11 12 1513

14


ProstaglandinsProstaglandins• among the prostaglandins synthesized biochemically

from arachidonic acid are

OH

COOH

O

HO HO

HO

COOH

OH

15

9 9

11 11

PGF2PGE2

15


ProstaglandinsProstaglandins• the observation that PGF2 stimulates contractions of

uterine smooth muscle led to the development of synthetic PGFs that can be used for therapeutic abortions

COOH

HO

HOHO CH3

HO

HO

COOH

HO H

PGF2

11

9

15 15

9

11

Carboprost(15S)-15-Methyl-PGF2

extra methyl groupat carbon-15


ProstaglandinsProstaglandins• the PGE1 analog, misoprostol, is used to prevent the

ulceration associated with the use of aspirin-like NSAIDs

COOCH3HO

O

HO

CH3

HO HHO

OCOOH

1615

MisoprostolPGE1

15 16


EicosanoidsEicosanoidsThe prostaglandins are members of an even larger The prostaglandins are members of an even larger

family of compounds called family of compounds called eicosanoidseicosanoids, all of , all of which contain 20 carbons and are derived from which contain 20 carbons and are derived from polyunsaturated fatty acidspolyunsaturated fatty acids• thromboxanes

O

OOH

COOH

Thromboxane A2(a potent vasoconstrictor)

189

11 201512


EicosanoidsEicosanoidsLeukotrienes Leukotrienes

• found primarily in white blood cells • one function is constriction of smooth muscles,

especially those of the lungs

S

OH

COOH

HN

NH

NH2

O

O

COOH

COOH

glycine

L-glutamic acidL-cysteine

20

14

11 9 76 5

1

Leukotriene C4 (LTC4)(a smooth muscle constrictor)


EicosanoidsEicosanoidsProstacyclinProstacyclin

O

OH OH

H H

HOOC6

79 8

1113

2014

Prostacyclin(a platelet aggregation inhibitor)

15

51


SteroidsSteroidsA group of plant and animal lipids that have this A group of plant and animal lipids that have this

tetracyclic ring structuretetracyclic ring structure


SteroidsSteroids Fats similar to, and usually synthesized from,

cholesterol.


SteroidsSteroidsFeatures common to steroidsFeatures common to steroids

• the fusion of rings is trans and each atom or group at a ring junction is axial

• the pattern of atoms or groups along the ring junctions is nearly always trans-anti-trans-anti-trans

• the steroid system is nearly flat and quite rigid• most have axial methyl groups at C-10 and C-13

HCH3

H

H

CH3

H

A BC D


SteroidsSteroidsCholesterolCholesterol

HO

Cholesterol has 8 stereocenters;256 stereoisomers are possible

HO

H3C

H3C

This is the stereoisomer found in human metabolism

** * * *

*

H

H

H

*

H3CH

H

*H


SteroidsSteroidsAndrogens - male sex hormonesAndrogens - male sex hormones

• synthesized in the testes• responsible for the development of male secondary sex

characteristics

AndrosteroneTestosteroneO

HOH

H

H3C H

H

H3C H3C

H

HH3C

H

O

HO


SteroidsSteroidsAnabolic steroidAnabolic steroid:: a steroid hormone, such as a steroid hormone, such as

testosterone, that promotes tissue and muscle testosterone, that promotes tissue and muscle growth and developmentgrowth and development

O

CH3HO

H3C

H3C

H H

H

O

OHH3C

H H

HH

HO

HOH3C

H3C

CH3

H H

H

Methandrostenolone Nandrolone Methandriol


SteroidsSteroidsEstrogensEstrogens:: female sex hormones female sex hormones

• synthesized in the ovaries• responsible for the development of female secondary

sex characteristics and control of the menstrual cycle

Progesterone Estrone

H3C

H

HH3C

H

C=OH

O

CH3

O

HO

H

H

H

H3C


Synthetic EstrogensSynthetic EstrogensProgesterone-like analogs are used in oral Progesterone-like analogs are used in oral

contraceptivescontraceptives

"Nor" refers to the absence of a methyl group here. It is present in ethindrone

Norethindrone

H3 C

H

HH

O

H

HO C CH


SteroidsSteroidsGlucocorticoid hormonesGlucocorticoid hormones

• synthesized in the adrenal cortex• regulate metabolism of carbohydrates• decrease inflammation• involved in the reaction to stress

CortisolCortisone

C=O

CH2OH

O

OH

H

H3C H

H

H3CO HO

H3C

H

HH3C

H

C=OOH

O

CH2OH


SteroidsSteroidsMineralocorticoid hormonesMineralocorticoid hormones

• synthesized in the adrenal cortex• regulates blood pressure and volume by stimulating

the kidneys to absorb Na+, Cl-, and HCO3-

Aldosterone

C=O

CH2 OH

O

H

H3 C H

H

CHO

OH


SteroidsSteroidsBile acidsBile acids

• synthesized in the liver, stored in the gallbladder, and secreted into the intestine

• emulsify dietary fats and aid in their absorption and digestion

H3C

HO

H3C

COOH

H H

H

HOH

Cholic acid


Steroid BiosynthesisSteroid BiosynthesisThe building block from which all carbon atoms of The building block from which all carbon atoms of

steroids are derived is the two-carbon acetyl steroids are derived is the two-carbon acetyl group of acetyl-CoAgroup of acetyl-CoAStage 1: synthesis of isopentenyl pyrophosphate from

three molecules of acetyl-CoA (Sect 16.5)

Stage 2: synthesis of cholesterol

Stage 3: conversion of cholesterol to other steroids

glucocorticoid hormones (e.g., cortisone)

mineralocorticoid hormones (e.g., aldosterone)

sex hormones (e.g., testosterone and estrone)

bile acids (e.g., cholic acid)

cholesterol


CH3-C-S-CoAO

(C10)

(C15)

(C30)

OH

HO CH3O-O

OP2O63-

Squalene

C10 terpenes

C15 and C20 terpenes

C30 terpenes

Cholesterol

Acetyl Coenzyme A

Isopentenyl pyrophosphate

(R)-Mevalonate

Geranyl pyrophosphate

Farnesyl pyrophosphate


Fat-Soluble VitaminsFat-Soluble VitaminsVitamins are divided into two broad classes on the Vitamins are divided into two broad classes on the

basis of their solubility basis of their solubility • those that are fat soluble (and hence classified as

lipids• those that are water soluble

The fat-soluble vitamins include A, D, E, and KThe fat-soluble vitamins include A, D, E, and K


Vitamin A (Retinol)Vitamin A (Retinol)• occurs only in the animal world • found in the plant world in the form of a provitamin in a

group of pigments called carotenes

CH2OH

Retinol (Vitamin A)

cleavage here

-Caroteneenzyme-catalyzedcleavage in the liver

2


Vitamin AVitamin AThe best understood role of vitamin A is its The best understood role of vitamin A is its

participation in the visual cycle in rod cellsparticipation in the visual cycle in rod cells• the active molecule is retinal (vitamin A aldehyde),

which forms an imine with an -NH2 group of the protein opsin to form the visual pigment called rhodopsin

• the primary chemical event of vision in rod cells is absorption of light by rhodopsin followed by isomerization of the 11-cis double bond to the 11-trans configuration


Vitamin AVitamin A• isomerization of the double bond at C11-C12 is

triggered by light striking rhodopsin

CH=N-opsin11

12

CH=N-opsin

1112

11-12 cis configuration

light


Vitamin AVitamin A• a group of structurally related compounds that play a

role in the regulation of calcium and phosphorus metabolism

• the most abundant form is vitamin D3

7-Dehydrocholesterol

Vitamin D3

HO

HO

UV light


Vitamin EVitamin EVitamin E: a group of compounds of similar Vitamin E: a group of compounds of similar

structurestructure• the most active is -tocopherol• vitamin E functions as an antioxidant; it traps peroxy

radicals of the type HOO• and ROO• formed as a result of oxidation by O2 of unsaturated hydrocarbon chains in membrane phospholipids

OH

O

Vitamin E (-Tocopherol)


Vitamin KVitamin K• the name of this vitamin comes from the German word

Koagulation, signifying its important role in the blood-clotting process

O

O O

O

Vitamin K1

isoprene units

2

Menadione(a synthetic vitamin K analog)


Nonglyceride Lipids Nonglyceride Lipids PhingolipidsPhingolipids

steroids, steroids,

waxeswaxes


Sphingolipids: SphingosineSphingolipids: SphingosineThese lipids are based on sphingosine, are found in These lipids are based on sphingosine, are found in

plants and animals, and are common in the nervous plants and animals, and are common in the nervous system.system.

CH CH CH2 CH3

CH OH

CH NH2

CH2OH

12

sphingosine


SphingolipidsSphingolipids

CH CH CH2 CH3

CH OH

CH NH

CH2OH

12

CO

R1

ceramideN-acylsphingosine

CH CH CH2 CH3

CH OH

CH NH

CH2O

12

OR1

P OO

CO

CH2CH2N+(CH3)3

sphingomyelinA ceramide with

phosphocholine or phosphoethanolamine as

head group


SphingoglycolipidsSphingoglycolipids

Attachment of carbohydrates to Attachment of carbohydrates to primaryprimary --OHOH of ceramideof ceramide

Cerebrosides: contain a single moiety, Cerebrosides: contain a single moiety, principally galactoseprincipally galactose

Sulfatides: sulfuric esters of Sulfatides: sulfuric esters of galactocerebrosidesgalactocerebrosides

Gangliosides: Gangliosides: contain contain a complex a complex oligosaccharide oligosaccharide moietymoiety


SphSphiingogngoglycolipids-2lycolipids-2

OCH2OH

HH

OHH

OH

OH

HH

OCH CH CH2

CH3CHOH

CHNH

CH2 12

C O

R1

a cerebroside

These compounds are found in the cell membranes of nerve and brain cells.


Clinical significance of sphingolipidsClinical significance of sphingolipids

R

R

R

Type 0

Type A

Type B

GlcNAc

Fucose

Galactose

Sialic acid (NANA)

Blood groups determined by various glycolipids on RBCs


EstrogensEstrogensThey are primarily responsible for the conversion of They are primarily responsible for the conversion of

girls into sexually-mature women. Participate in girls into sexually-mature women. Participate in the monthly preparation of the body for a the monthly preparation of the body for a possible pregnancy. Participate in pregnancy if it possible pregnancy. Participate in pregnancy if it occurs occurs


Anabolic steroidsAnabolic steroids

A number of synthetic androgens promote A number of synthetic androgens promote an increase in body weight and muscle an increase in body weight and muscle strength: popular with athletes, weight strength: popular with athletes, weight lifters, cyclists, professional football lifters, cyclists, professional football players, etc. players, etc.

Often these athletes take doses 100 time Often these athletes take doses 100 time greater than those used in standard greater than those used in standard therapy. Such illicit use therapy. Such illicit use

Side effects: acne, a decrease in libido, Side effects: acne, a decrease in libido, testicle size, and sperm counts to name a testicle size, and sperm counts to name a few. few.


Complex lipidsComplex lipidsLipoproteinsLipoproteins

Lipoproteins are composed of a neutral core of Lipoproteins are composed of a neutral core of cholesterol and triacylglycerols. cholesterol and triacylglycerols.

GlycolipidsGlycolipids

Sugar containing lipidsSugar containing lipids


Four major groups of plasma lipoproteins. Four major groups of plasma lipoproteins.

1. Chylomicrons 1. Chylomicrons

2. Very low-density lipoproteins (VLDL) 2. Very low-density lipoproteins (VLDL)

3. Low-density lipoproteins (LDL) 3. Low-density lipoproteins (LDL)

4. High-density lipoproteins (HDL) 4. High-density lipoproteins (HDL)


The roles of HDL, LDL, and cholesterol. The roles of HDL, LDL, and cholesterol.

Cholesterol and lipoproteins are related plaque that Cholesterol and lipoproteins are related plaque that causes heart attacks and most strokes. causes heart attacks and most strokes.

When LDL levels are low, atherosclerosis and heart When LDL levels are low, atherosclerosis and heart attacks are almost unknown.attacks are almost unknown.

High HDL levels are associated with a reduced risk High HDL levels are associated with a reduced risk of heart disease: "good" cholesterolof heart disease: "good" cholesterol


SphingolipidsSphingolipidsThese lipids are based on sphingosine, are found in These lipids are based on sphingosine, are found in

plants and animals, and are common in the nervous plants and animals, and are common in the nervous system.system.

CH CH CH2 CH3

CH OH

CH NH2

CH2OH

12

sphingosine



CH CH CH2 CH3

CH OH

CH NH

CH2OH

12

CO

R1

ceramideN-acylsphingosine

CH CH CH2 CH3

CH OH

CH NH

CH2O

12

OR1

P OO

CO

CH2CH2N+(CH3)3

sphingomyelinA ceramide with

phosphocholine or phosphoethanolamine as

head group


SphingoglycolipidsSphingoglycolipids

Attachment of carbohydrates to Attachment of carbohydrates to primaryprimary --OHOH of ceramideof ceramide

Cerebrosides: contain a single moiety, Cerebrosides: contain a single moiety, principally galactoseprincipally galactose

Sulfatides: sulfuric esters of Sulfatides: sulfuric esters of galactocerebrosidesgalactocerebrosides

Gangliosides: Gangliosides: contain contain a complex a complex oligosaccharide oligosaccharide moietymoiety


SphSphiingogngoglycolipids-2lycolipids-2

OCH2OH

HH

OHH

OH

OH

HH

OCH CH CH2

CH3CHOH

CHNH

CH2 12

C O

R1

a cerebroside

These compounds are found in the cell membranes of nerve and brain cells.


Clinical significance of sphingolipidsClinical significance of sphingolipids

R

R

R

Type 0

Type A

Type B

GlcNAc

Fucose

Galactose

Sialic acid (NANA)

Blood groups determined by various glycolipids on RBCs

19-1 chemistry 121 winter 2009 la tech chapter 19. lipids sections

Documents

membrane lipids

messenger lipids

la tech lipids

acetone lipids

emulsification lipids

types of lipids

lipids sections

carboxylic acids