Lipids A heterogeneous class of naturally occurring...

1

19-1 Chemistry 121 Winter 2011 LA Tech

Introduction to Organic Chemistry and Biochemistry

Instructor Dr. Upali Siriwardane (Ph.D. Ohio State)

E-mail: [email protected]

Office: 311 Carson Taylor Hall ; Phone: 318-257-4941;

Office Hours: MWF 8:00 am - 10:00 am;

TT 9:00 – 10:00 am & 1:00-2:00 pm.

December 17, 2010 Test 1 (Chapters 12-13)

January 19, 2011 Test 2 (Chapters 14,15 & 16)

February 7, 2011 Test 3(Chapters 17, 18 & 19)

February 23, 2011 Test 4 (Chapters 20, 21 & 22)

February 24, 2011 Comprehensive Make Up Exam:

Chemistry 121(01) Winter 2010-11


Chapter 19. Lipids

Sections


Chapter 19

19.1 Structure and Classification of Lipids

19.2 Fatty Acids: Lipid Building Blocks

19.3 Physical Properties of Fatty Acids

19.4 Energy-Storage Lipids: Triacylglycerols

19.5 Dietary Considerations and Triacylglycerols

19.6 Chemical Reactions of Triacylglycerols

19.7 Membrane Lipids: Phospholipids

19.8 Membrane Lipids: Sphingoglycolipids

19.9 Membrane Lipids: Cholesterol

19.10 Cell Membranes

19.11 Emulsification Lipids: Bile Acids

19.12 Messenger Lipids: Steroid Hormones

19.13 Messenger Lipids: Eicosanoids

19.14 Protective-Coating Lipids: Biological Waxes

Chemistry at a Glance: Types of Lipids and How They Function

Chemical Connections: The Fat Content of Tree Nuts and Peanuts;

Artificial Fat Substitutes; The Cleansing Action of Soap; Trans Fatty

Acids and Blood Cholesterol Levels; Steroid Drugs in Sports; The Mode

of Action for Anti-Inflammatory Drugs


Lipids A heterogeneous class of naturally occurring

organic compounds classified together on the

basis of common solubility properties

• insoluble in water

• soluble in aprotic organic solvents including diethyl

ether, dichloromethane, and acetone

Lipids include

• Waxes

• triglycerides

• phospholipids

• Prostaglandins

• cholesterol, steroid hormones, and bile acids

• fat-soluble vitamins

2


Structure and Classification of Lipids

Lipids that are ester or amides of fatty acids: Waxes – 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

chain.

Performs external protective functions. Performs external protective functions.

Triglycerides– are carboxylic acid are carboxylic acid triesters of

Glycerols . They are a major source of biochemical energy.

Glycolipids – amides derived from sphingosine, contain polar carbohydrate groups. On the

cell surface, they connect with intracellular messengers.

Glycerophopholipids – triesters of glycerols that contain charged phosphate diesters. They

help to control the flow of molecules into and out of cells.

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

alcohol, phosphate diester groups. They are essential to the structure of cell membranes.

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

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

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

Messengers.


Wax

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

alcohols.

They 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

chain.

They performs external protective functions. Performs external protective functions.

Beeswax

Spermaciti: sperm whale wax

O

CH3(CH

2)24

O (CH2)29

CH3

O

CH3(CH

2)14

O (CH2)15

CH3


Bee’s wax

Spermaceti source

Carnauba wax source


Triglycerides

CH2OH

CHOH

CH2OH

CH2

CH

2

CH

O

O

O

O

O

O

RCOOH

Glycerol

Saturated Fat or Oil

3


Properties of Fats and Oils

Oils: A mixture of triglycerides that is liquid

because it contains a high proportions of unsaturated

fatty acids.

Fats : A mixture of triglycerides that is solid because it

contains a high proportions of saturated fatty acids.


Physical properties of Triglycerides

Depends 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 oils

• triglycerides rich in saturated fatty acids are generally

semisolids or solids at room temperature and are

called fats


Triglycerides The lower melting points of triglycerides rich in

unsaturated fatty acids are related to differences

in 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 Triglycerides • the process of converting fats to oils is called

hardening 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

4


Triglycerides An ester of glycerol with three fatty acids

CH2OCR

CH2OCR''

R'COCH

O

O

O

1. NaOH, H2O

2. HCl, H2 O

CH2 OH

CH2 OH

HOCH

RCOOH

R'COOH

R''COOH

1,2,3-Propanetriol(Glycerol, glycerin)

+

Fatty acidsA triglyceride


Soaps and Detergents Natural soaps are prepared by boiling lard or other

animal fat with NaOH, in a reaction called

saponification (Latin, sapo, 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 Detergents Soaps 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

• Micelle: 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 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

5


Soaps Soaps form water-insoluble salts when used in

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

(hard water)

2CH3 (CH2 )14COO-Na

+2CH3 (CH2 )14COO

-Na

+Ca

2 +Ca

2 +

[CH3 (CH2 ) 1 4COO-]2 Ca

2+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 Detergents The 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 Acids A 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 Acids The most abundant fatty acids

CH3 ( CH2 ) 1 2COOH

CH3 ( CH2 ) 1 0COOH

CH3 ( CH2 ) 1 4COOH

CH3 ( CH2 ) 1 6COOH

CH3 ( CH2 ) 1 8COOH

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

63

stearic acid

palmitic acid

Unsaturated Fatty Acids

Saturated Fatty Acids

20:4

18:3

18:2

18:1

16:1

20:0

18:0

16:0

14:0

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

myris tic acid

lauric acid

6


Saturated Fatty Acids


Saturated/Unsturated fatty acids


Unsaturated Fatty Aicds


Saturated/Unsturated fatty acids

7


Saturated/Unstaureated Mixtures


Fatty Acids the greater the degree of unsaturation the lower the

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)


Unsaturated triglyceride


What are "Omega" series fatty acids?

Scientists differentiate fatty acids by the

characteristics of their molecules. The two

principal essential fatty acids are Omega-6

(n-6) series and the Omega-3(n-3) series. The

number indicates the position of the first double

carbon bond when counting from a specified end

of the molecule.

8


Essential Fatty Acids

Fatty acids that cannot be produced by the body

and are necessary for proper metabolism. The

OMEGA 6 and OMEGA 3 fatty acids are referred

to as Essential Fatty Acids (EFA).


Phospholipids Phospholipids are the second most abundant

group of 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

Phosphate(PO4 )-containing molecules with

structures related to the triglycerides are aclled

Glycerophopholipids

E.g. Phosphatidycholine (lecithin)


Examples of glycerophospholipids

Name

Phosphatidyl choline (lecithin)

Phosphatidyl ethanolamine (cephalin)

9


Phospholipids A phosphatidate and a phospholipid

CH2

CH

CH2

O

O

O

O

O-P-O-

O

O-

CH2

CH

CH2 -O-P-OCH2 CH2 N(CH3 ) 3

O

O

O

O

O-

O

A phosphatidate

A phospholip id

nonpolarhydrocarbon

tails polar head groups


Phospholipids


Phosphatidycholine (lecithin)


Phospholipids • low-molecular weight alcohols in phospholipids

NH3+

HOCH2CHCOO-

HOCH2CH2N(CH3 )3

HOCH2CH2NH2

HO

HOOH

OH

OHHO

Name and Formula Name of Phospholipid

ethanolamine

+choline

phosphatidy lcholine(lecithin)

phosphatidy leth anolamine

(ceph al in)

serineph osphatidy lserine

inosito l

phosp hatid yl inositol

10


Lipid Bilayer When placed in aqueous solution, phospholipids

spontaneously form a lipid 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

forces

• hydrophobic effects, which result when nonpolar

hydrocarbon chains cluster to exclude water molecules

• electrostatic interactions, which result when polar head

groups interact with water and other polar molecules in

the aqueous environment


Plasma membrane

Planar lipid bilayers

Biological membranes are bilipid layers .

In a real cell the membrane phospholipids create a

spherical three dimensional lipid

bilayer shell around the cell. However, they are

often represented two-dimensionally as:

Passive tranport

Active transport


Biological Membranes Fluid mosaic model: a biological membrane

consists of a phospholipid bilayer with proteins,

carbohydrates, and other lipids embedded on the

surface and in the bilayer

• fluid signifies that the protein components of

membranes “float” in the bilayer and can move freely

along the plane of the membrane

• mosaic 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 Model

11


Prostaglandins

Essential fatty acids in the cell membranes

produce prostaglandins.

Prostaglandins regulate bodily functions in the

heart, kidneys, liver, lungs, brain,

nerves and the immune system.


Types of Prostaglandins In human beings, there are three families of

prostaglandins, each of which is derived

from a different fatty acid.

Prostaglandin PG

PGE1

PGF1

PGE2

PGF2

Eicosanoids

Thromboxane A2

Leukotriene B4


Prostaglandins Prostaglandins: a family of compounds that have

the 20-carbon skeleton of prostanoic acid

Prostanoic acid

192018

1716

1514

13

78

9

10

1112

6

5

4

3

2

1CO2 H


Prostaglandins Prostaglandins are not stored in tissues as such,

but are synthesized from membrane-bound 20-

carbon polyunsaturated fatty acids in response to

specific physiological triggers

• one such polyunsaturated fatty acid is arachidonic acid

COOH

Arachidonic acid

9 8

11 12 1513

14

12


Prostaglandins • among the prostaglandins synthesized biochemically

from arachidonic acid are

OH

COOH

O

HO HO

HO

COOH

OH

15

9 9

11 11

PGF2PGE2

15


Prostaglandins • 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


Prostaglandins

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

ulceration associated with the use of aspirin-like

NSAIDs

COOCH3HO

O

HO

CH3

HO HHO

O

COOH

1615

MisoprostolPGE1

15 16


Eicosanoids The prostaglandins are members of an even larger

family of compounds called eicosanoids, all of

which contain 20 carbons and are derived from

polyunsaturated fatty acids

• thromboxanes

O

O

OH

COOH

Thromboxane A2

(a potent vasoconstrictor)

189

112015

12

13


Eicosanoids 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)


Eicosanoids Prostacyclin

O

OH OH

H H

HOOC

6

79 8

11

13

2014

Prostacyclin(a platelet aggregation inhibitor)

15

51


Steroids A group of plant and animal lipids that have this

tetracyclic ring structure


Steroids

Fats similar to, and usually synthesized from,

cholesterol.

14

19-53 Chemistry 121 Winter 2011 LA Tech 19-54 Chemistry 121 Winter 2011 LA Tech

Steroids Features 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


Steroids Cholesterol

HO

Cholesterol has 8 s tereocenters;256 stereoisomers are possible

HO

H3 C

H3 C

This is the stereoisomer found in human metabolism

**

* * **

H

H

H

*

H3 CH

H

*H


Steroids Androgens - male sex hormones

• synthesized in the testes

• responsible for the development of male secondary sex

characteristics

AndrosteroneTestosterone

O

H

OH

H

H3 C H

H

H3 C H3 C

H

HH3 C

H

O

HO

15


Steroids Anabolic steroid: a steroid hormone, such as

testosterone, that promotes tissue and muscle

growth and development

O

CH3HO

H3C

H3C

H H

H

O

OHH3 C

H H

HH

HO

HOH3C

H3 C

CH3

H H

H

Methandrostenolone Nandrolone Methandriol


Steroids Estrogens: female sex hormones

• synthesized in the ovaries

• responsible for the development of female secondary

sex characteristics and control of the menstrual cycle

Progesterone Estrone

H3 C

H

HH3 C

H

C=O

H

O

CH3

O

HO

H

H

H

H3 C


Synthetic Estrogens Progesterone-like analogs are used in oral

contraceptives

"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


Steroids Glucocorticoid hormones

• synthesized in the adrenal cortex

• regulate metabolism of carbohydrates

• decrease inflammation

• involved in the reaction to stress

CortisolCortisone

C=O

CH2 OH

O

OH

H

H3 C H

H

H3 CO HO

H3 C

H

HH3 C

H

C=O

OH

O

CH2 OH

16


Steroids Mineralocorticoid 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


Steroids Bile acids

• synthesized in the liver, stored in the gallbladder, and

secreted into the intestine

• emulsify dietary fats and aid in their absorption and

digestion

H3 C

HO

H3 C

COOH

H H

H

HOH

Cholic acid


Steroid Biosynthesis The building block from which all carbon atoms of

steroids are derived is the two-carbon acetyl

group of acetyl-CoA

Stage 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-CoA

O

( C1 0)

( C1 5)

( C3 0)

OH

HO CH3O

-O

OP2 O63 -

Squalene

C10 terpenes

C15 and C20 terpenes

C30 terpenes

Cholesterol

Acetyl Coenzyme A

Isopentenyl pyrophosphate

(R)-Mevalonate

Geranyl pyrophosphate

Farnesyl pyrophosphate

Biosynthesis Choresterol

17


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

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 K


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

-Carotene

enzyme-catalyzedcleavage in the liver

2


Vitamin A The best understood role of vitamin A is its

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

triggered by light striking rhodopsin

CH= N-opsin11

12

CH= N-opsin

11

12

11-12 cis configuration

light

18


Vitamin 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 D 3

HO

HO

UV light


Vitamin E Vitamin E: a group of compounds of similar

structure

• 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 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 Sphingolipids

steroids,

waxes

19


Sphingolipids: Sphingosine

These lipids are based on sphingosine, are found in

plants and animals, and are common in the nervous

system.


Sphingolipids

CH CH CH2

CH3

CH OH

CH NH

CH2OH

12

CO

R1

ceramide N-acylsphingosine

CH CH CH2

CH3

CH OH

CH NH

CH2O

12

OR1

P OO

CO

CH2CH

2N

+(CH

3)3

sphingomyelin

A ceramide with

phosphocholine or

phosphoethanolamine as

head group


Sphingoglycolipids

Attachment of carbohydrates to primary -OH of ceramide

Cerebrosides: contain a single moiety, principally galactose

Sulfatides: sulfuric esters of galactocerebrosides

Gangliosides: contain a complex oligosaccharide moiety


Sphingolipids

20


Sphingoglycolipids-2

OCH

2OH

HH

OHH

OH

OH

HH

O

CH CH CH2

CH3CH

OH

CH

NH

CH2 12

C O

R1

a cerebroside

These compounds are found in the cell membranes of nerve and brain cells. 19-78 Chemistry 121 Winter 2011 LA Tech

Clinical 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


Estrogens They are primarily responsible for the conversion of

girls into sexually-mature women. Participate in

the monthly preparation of the body for a

possible pregnancy. Participate in pregnancy if it

occurs


Anabolic steroids

A number of synthetic androgens promote

an increase in body weight and muscle

strength: popular with athletes, weight

lifters, cyclists, professional football

players, etc.

Often these athletes take doses 100 time

greater than those used in standard

therapy. Such illicit use

Side effects: acne, a decrease in libido,

testicle size, and sperm counts to name a

few.

21


Complex lipids Lipoproteins

Lipoproteins are composed of a neutral core of

cholesterol and triacylglycerols.

Glycolipids

Sugar containing lipids


Four major groups of plasma lipoproteins.

1. Chylomicrons

2. Very low-density lipoproteins (VLDL)

3. Low-density lipoproteins (LDL)

4. High-density lipoproteins (HDL)


The roles of HDL, LDL, and cholesterol.

Cholesterol and lipoproteins are related plaque that

causes heart attacks and most strokes.

When LDL levels are low, atherosclerosis and heart

attacks are almost unknown.

High HDL levels are associated with a reduced risk

of heart disease: "good" cholesterol


Sphingolipids

These lipids are based on sphingosine, are found in

plants and animals, and are common in the nervous

system.

CH CH CH2

CH3

CH OH

CH NH2

CH2OH

12

sphingosine

22


Sphingolipids

CH CH CH2

CH3

CH OH

CH NH

CH2OH

12

CO

R1

ceramide N-acylsphingosine

CH CH CH2

CH3

CH OH

CH NH

CH2O

12

OR1

P OO

CO

CH2CH

2N

+(CH

3)3

sphingomyelin

A ceramide with

phosphocholine or

phosphoethanolamine as

head group 19-86 Chemistry 121 Winter 2011 LA Tech

Sphingoglycolipids

Attachment of carbohydrates to primary -OH of ceramide

Cerebrosides: contain a single moiety, principally galactose

Sulfatides: sulfuric esters of galactocerebrosides

Gangliosides: contain a complex oligosaccharide moiety


Sphingoglycolipids-2

OCH

2OH

HH

OHH

OH

OH

HH

O

CH CH CH2

CH3CH

OH

CH

NH

CH2 12

C O

R1

a cerebroside

These compounds are found in the cell membranes of nerve and brain cells. 19-88 Chemistry 121 Winter 2011 LA Tech

Clinical 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

Lipids A heterogeneous class of naturally occurring...

Documents

Transcript of Lipids A heterogeneous class of naturally occurring...