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Introduction Definition: water insoluble compounds
Most lipids are fatty acids or ester of fatty acid They are soluble in non-polar solvents such as petroleum
ether, benzene, chloroform Functions
Energy storage Structure of cell membranes Thermal blanket and cushion
Precursors of hormones (steroids and prostaglandins) Types:
Fatty acids Neutral lipids Phospholipids and other lipids
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Fatty acids Carboxylic acid derivatives of long chain hydrocarbons
Nomenclature (somewhat confusing)
Stearate stearic acid C18:0
n-octadecanoic acid
General structure:
(CH2)nCH3 COOH
n is almost always even
n = 0 : CH3COOH n = 1 : propionic aci
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Fatty acids Common fatty acids
n = 4 butyric acid (butanoic acid)
n = 6 caproic acid (hexanoic acid)n = 8 caprylic acid (octanoic acid)
n = 10 capric acid (decanoic acid)
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Fatty acids common FAs:
n = 12: lauric acid (n-dodecanoic acid; C12:0)n = 14: myristic acid (n-tetradecanoic acid; C
14:0)
n = 16: palmitic acid (n-hexadecanoic acid; C16:0)
n = 18; stearic acid (n-octadecanoic acid; C18:0)
n = 20; arachidic (eicosanoic acid; C20:0)
n= 22; behenic acid
n = 24; lignoceric acid
n = 26; cerotic acid
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Less common fatty acids
iso isobutyric acid
anteiso
odd carbon fatty acid propionic acid hydroxy fatty acids ricinoleic acid,
dihydroxystearic acid, cerebronic acid
cyclic fatty acids hydnocarpic, chaulmoogricacid
R
H3C
H3C H3C
R
CH3
(CH2)12-CO2H (CH2)10-CO2H
chaulmoogric acid hydnocarpic acid
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H3C
CH3 CH3 CH3 CH3
COOH
PHYTANIC ACID
A plant derived fatty acid with 16 carbons and branches at C 3, C7, C11 and
C15. Present in dairy products and ruminant fats.
A peroxisome responsible for the metabolism of phytanic acid is defective
in some individuals. This leads to a disease called Refsums disease
Refsums disease is characterized by peripheral polyneuropathy, cerebellar
ataxia and retinitis pigmentosa
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(CH2)10H3C C C (CH2)4 COOH
TARIRIC ACID
CHH2C (CH2)4 C C C C (CH2)7 COOH
ERYTHROGENIC ACID
Less common fatty acids
These are alkyne fatty acids
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Fatty acids Fatty acids can be classified either as:
saturated or unsaturated
according to chain length: short chain FA: 2-4 carbon atoms
medium chain FA: 6 10 carbon atoms
long chain FA: 12 26 carbon atoms
essential fatty acids vs those that can be biosynthesized in the
body: linoleic and linolenic are two examples of essential fatty acid
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Unsaturated fatty acids Monoenoic acid (monounsaturated)
H3C
HOOC
Double bond is alwayscis in natural fatty acids.
This lowers the melting
point due to kink in
the chain
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Unsaturated fatty acids Dienoic acid: linoleic acid
(CH2)4CH3 CH=CH CH2 CH=CH (CH2)7 COOH
cis
linoleic acid
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Unsaturated fatty acidsVarious conventions are in use for indicating the
number and position of the double bond(s)
HC CH(CH2)7COOH(CH2)7H3C
1918
10
18:1,9 or9
18:1
H3C CH2CH 2CH2CH2CH2CH2CH2CH CH( CH2)7COOH
191017n
2 3 4 5 6 7 8 9 10 18
9, C18:1 or n-9, 18:1
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Unsaturated fatty acids Polyenoic acid (polyunsaturated)
COOH
CH3
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Unsaturated fatty acids Monoenoic acids (one double bond):
16:1, 9 7: palmitoleic acid (cis-9-hexadecenoic acid
18:1, 9 9: oleic acid (cis-9-octadecenoic acid)
18:1, 9 9: elaidic acid (trans-9-octadecenoic acid)
22:1, 13 9: erucic acid (cis-13-docosenoic acid)
24:1, 15 9: nervonic acid (cis-15-tetracosenoic acid)
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Unsaturated fatty acids Trienoic acids (3 double bonds)
18:3;6,9,12 6 : g-linolenic acid (all cis-6,9,12-octadecatrienoicacid)
18:3; 9,12,15 3 : a-linolenic acid (all-cis-9,12,15-octadecatrienoic acid)
Tetraenoic acids (4 double bonds) 20:4; 5,8,11,14 6: arachidonic acid (all-cis-5,8,11,14-
eicosatetraenoic acid)
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Unsaturated fatty acids
Pentaenoic acid (5 double bonds) 20:5; 5,8,11,14,17 3: timnodonic acid or EPA
(all-cis-5,8,11,14,17-eicosapentaenoic acid)*
Hexaenoic acid (6 double bonds) 22:6; 4,7,10,13,16,19 3: cervonic acid or DHA
(all-cis-4,7,10,13,16,19-docosahexaenoic acid)*
Both FAs are found in cold water fish oils
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Typical fish oil supplements
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Properties of fats and oils fats are solids or semi solids
oils are liquids
melting points and boiling points are not usuallysharp (most fats/oils are mixtures)
when shaken with water, oils tend to emulsify
pure fats and oils are colorless and odorless (color
and odor is always a result of contaminants) i.e.butter (bacteria give flavor, carotene gives color)
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Examples of oils Olive oil from Oleo europa (olive tree)
Corn oil fromZea mays
Peanut oil fromArachis hypogaea Cottonseed oil from Gossypium
Sesame oil from Sesamum indicum
Linseed oil from Linum usitatissimum
Sunflower seed oil from Helianthus annuus Rapeseed oil from Brassica rapa
Coconut oil from Cocos nucifera
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Non-drying, semi-drying and drying oils based on the ease of autoxidation and
polymerization of oils (important in paints andvarnishes)
the more unsaturation in the oil, the more likelythe drying process Non-drying oils:
Castor, olive, peanut, rapeseed oils
Semi-drying oils Corn, sesame, cottonseed oils
Drying oils Soybean, sunflower, hemp, linseed, tung, oiticica oils
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Fatty acid reactions salt formation
ester formation
lipid peroxidation
RCO2H RCO2-Na+
NaOH(a soap)
R'OH + RCO2H RCO2R'-H20
R
R'
H H
R R'
OOH
O2
non-enzymatic
very reactive
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Soaps
Process of formation is known as saponification Types of soaps:
Sodium soap ordinary hard soap
Potassium soap soft soap (shaving soaps are potassium
soaps of coconut and palm oils) Castile soap sodium soap of olive oil
Green soap mixture of sodium and potassium linseed oil
Transparent soap contains sucrose
Floating soap contains air
Calcium and magnesium soaps are very poorly water soluble(hard water contains calcium and magnesium salts theseinsolubilize soaps)
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Lipid peroxidation a non-enzymatic reaction catalyzed by oxygen
may occur in tissues or in foods (spoilage) the hydroperoxide formed is very reactive and leads to
the formation of free radicals which oxidize proteinand/or DNA (causes aging and cancer)
principle is also used in drying oils (linseed, tung,walnut) to form hard films
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Hydrogenated fats hydrogenation leads to either saturated fats and or
trans fatty acids
the purpose of hydrogenation is to make the oil/fatmore stable to oxygen and temperature variation(increase shelf life)
example of hydrogenated fats: Crisco, margarine
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Neutral lipids Glycerides (fats and oils) ;glycerides
Glycerol
Ester of glycerol - mono glycerides, diglycerides andtriglycerides
Waxes simple esters of long chain alcohols
CH2OH
CH2OH
OHH OH
OH
OH
glycerol is a prochiral molecule
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GLYCERIDES
O
OH
OH
R
O
O
OH
O
R
O
R
O
O
O
R
O
R
O
OR
O
MONOGLYCERIDE DIGLYCERIDE TRIGLYCERIDE
Function: storage of energy in compact form and cushioning
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WAXES
simple esters of fatty acids (usually saturated with longchain monohydric alcohols)
H3C (CH 2)14 C
O
O CH 2 (CH 2)28-CH 3
long chain alcohol
fatty acid
Beeswaxalso includes some free alcohol and fatty acids
Spermaceticontains cetyl palmitate (from whale oil)useful for
Pharmaceuticals (creams/ointments; tableting and granulation)
Carnauba waxfrom a palm tree from brazila hard wax used on
cars and boats
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Bees wax
Spermaceti source
Carnauba wax source
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Waxes
(CH2)14H3C CH2-OH cetyl alcohol
(CH2)24H3C CH2-OH hexacosanol
(CH2)28H3C CH2-OH triacontanol (myricyl alcoh
Examples of long chain monohydric alcohols found in waxes
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Phospholipids the major components of cell membranes
phosphoglycerides
O R
O R'
O
P
O
O
O
O-
X
Ofatty acids (hydrophobic tail)
glycerol
phosphate
Phospholipids are generally composed of FAs, a nitrogenous base, phosphoric
acid and either glycerol, inositol or sphingosine
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O R
O R'
O
P
O
O
O
O-
X
Ofatty acids (hydrophobic tail)
glycerol
phosphate
X = H (phosphatidic acid) - precursor to other phospholipids
X = CH2-CH2-N+(CH3)3 phosphatidyl choline
X = CH2-CH(COO-)NH3
+phosphatidyl serine
X = CH2-CH2-NH3+
phosphatidyl ethanolamine
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Phosphatidyl inositol
Commonly utilized in cellular signaling
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Sphingolipids
OH
NH2
OH
NH2
OH
HO Rlong chain hydrocarbon
attach fatty acid here
attach polar head group here
sphingosine
Based on sphingosine instead of glycerol
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Sphingomyelin (a ceramide)
NH
O
HO R
PO
O-
O
N(CH3)+
R'
O
usually palmitic acid
phosphatidyl choline (also can be ethanolami
It is a ubiquitous component of animal cell membranes, where it is by far the most
abundant sphingolipid. It can comprise as much as 50% of the lipids in certain tissues,
though it is usually lower in concentration than phosphatidylcholine
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Ether glycerophospholipids Possess an ether linkage instead of an acyl group at the
C-1 position of glycerol PAF ( platelet activating factor)
A potent mediator in inflammation, allergic response and inshock (also responsible for asthma-like symptom
The ether linkage is stable in either acid or base
Plasmalogens: cis a,b-unsaturated ethers
The alpha/beta unsaturated ether can be hydrolyzed more easily
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Ether glycerophospholipids
H2C CH
O
CH2
O
O
P
O
-O O
C O
CH3
CH2
CH2
N
CH3
CH3
CH3
platelet activating factor or PAF
H2C CH
O
CH2
O
O
P
O
-O O
C O
CH2 CH2 N
CH3
CH3
CH3
A choline plasmalogen
H
H
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glycolipids
NH
O
HO R
R'
O
SUGAR polar head is a suga
beta linkage
There are different types of glycolipids: cerebrosides, gangliosides,
lactosylceramides
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GLYCOLIPIDS Cerebrosides
One sugar molecule Galactocerebroside in neuronal membranes Glucocerebrosides elsewhere in the body
Sulfatides or sulfogalactocerebrosides A sulfuric acid ester of galactocerebroside
Globosides: ceramide oligosaccharides Lactosylceramide
2 sugars ( eg. lactose) Gangliosides
Have a more complex oligosaccharide attached Biological functions: cell-cell recognition; receptors for
hormones
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Gangliosides complex glycosphingolipids that consist of a ceramide
backbone with 3 or more sugars esterified,one of thesebeing a sialic acid such as N-acetylneuraminic acid
common gangliosides: GM1, GM2, GM3, GD1a, GD1b, GT1a,GT1b, Gq1b
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Ganglioside nomenclature letter G refers to the name ganglioside
the subscripts M, D, T and Q indicate mono-, di-, tri,and quatra(tetra)-sialic-containing gangliosides
the numerical subscripts 1, 2, and 3 designate thecarbohydrate sequence attached to ceramide
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Ganglioside nomenclature Numerical subscripts:
1. Gal-GalNAc-Gal-Glc-ceramide
2. GalNAc-Gal-Glc-ceramide
3. Gal-Glc-ceramide
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O
CH 2OH
H OH
H
OH
OH
O
O
CH 2OH
H NH
H
OH
O
CH 2OH
H OH
H
H
O
CH 2OH
H OH
H
H
OH H
O
H
O
O
CH 2HC
HC
NH
C O
R
HO
C
C
O
O
C O
CH 3
NH
H
CHOH
CHOH
OH
CH 2OH
H
H
COO-C
O
H3C
H
H
H
H
D-Galactose
N-Acetyl-D-galactosamine D-galactose D-glucose
N-acetylneuraminidate (sialic acid)
A ganglioside (GM1)
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Cardiolipids
C
H2C O
O
H2C O P
O
OH
O
C
O
R1
C
O
R2
CH2 C
OH
H
CH2 O P O
OH
O
CH2
C OH
CH2O
C
O
R3
C
O
R4
H
glycerolglycerol
glycerol
A polyglycerol phospholipid; makes up 15% of total lipid-phosphorus
content of the myocardiumassociated with the cell membrane
Cardiolipids are antigenic and as such are used in serologic test for
syphilis (Wasserman test)
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Sulfolipids also called sulfatides or cerebroside sulfates
contained in brain lipids
sulfate esters of cerebrosides present in low levels in liver, lung, kidney, spleen,
skeletal muscle and heart
function is not established
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Lipid storage diseases also known as sphingolipidoses
genetically acquired
due to the deficiency or absence of a catabolic enzyme
examples: Tay Sachs disease
Gauchers disease
Niemann-Pick disease
Fabrys disease
http://www.ninds.nih.gov/disorders/lipid_storage_diseases/lipid_storage_diseases.htm
http://www.ninds.nih.gov/disorders/lipid_storage_diseases/lipid_storage_diseases.htmhttp://www.ninds.nih.gov/disorders/lipid_storage_diseases/lipid_storage_diseases.htmhttp://www.ninds.nih.gov/disorders/lipid_storage_diseases/lipid_storage_diseases.htmhttp://www.ninds.nih.gov/disorders/lipid_storage_diseases/lipid_storage_diseases.htm7/30/2019 Lec 4 Lipids
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Genetic defects in ganglioside metabolism leads to a buildup of gangliosides (ganglioside GM2) in
nerve cells, killing them
NAcGal Gal Gal Glu
NAcNeu
enzyme that hydrolyzes here (beta hexosaminod
is absent in Tay-Sachs disease
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Tay-Sachs disease a fatal disease which is due to the deficiency of
hexosaminidase A activity accumulation of ganglioside GM2 in the brain of
infants mental retardation, blindness, inability to
swallow a cherry red spot develops on the macula
(back of the the eyes) Tay-Sachs children usually die by age 5 and
often sooner
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Genetic defects in globoside metabolism Fabrys disease:
Accumulation of ceramide trihexoside in kidneys of patientswho are deficient in lysosomal a-galactosidase A sometimes
referred to as ceramide trihexosidase Skin rash, kidney failure, pains in the lower extremities
Now treated with enzyme replacement therapy: agalsidasebeta (Fabrazyme)
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Genetic defects in cerebroside metabolism Krabbes disease:
Also known as globoid leukodystrophy Increased amount of galactocerebroside in the white matter of the brain Caused by a deficiency in the lysosomal enzyme galactocerebrosidase
Gauchers disease: Caused by a deficiency of lysosomal glucocerebrosidase Increase content of glucocerebroside in the spleen and liver Erosion of long bones and pelvis Enzyme replacement therapy is available for the Type I disease
(Imiglucerase or Cerezyme) Also miglustat (Zavesca) an oral drug which inhibits the enzyme
glucosylceramide synthase, an essential enzyme for the synthesis ofmost glycosphingolipids
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Miglustat (Zavesca)
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Genetic defects in ganglioside metabolism Metachromatic leukodystrophy
accumulation of sulfogalactocerebroside (sulfatide) in the centralnervous system of patient having a deficiency of a specific
sulfatase mental retardation, nerves stain yellowish-brown with cresyl
violet dye (metachromasia)
Generalized gangliosidosis
accumulation of ganglioside GM1 deficiency of GM1 ganglioside: b-galactosidase
mental retardation, liver enlargement, skeletal involvement
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Niemann-Pick disease principal storage substance: sphingomyelin which
accumulates in reticuloendothelial cells
enzyme deficiency: sphingomyelinase
liver and spleen enlargement, mental retardation
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Blood groups
determined by various glycolipids on RBCs
A antigens
B antigens
H antigens
AcN Gal
L-Fucose
Ac
N Glu-sphingosine
Gal Gal NAc-Glu-sphingosine
L-Fucose
Gal NAc--Glu-sphingosine
L-Fucose
not recognized by anti-A or anti-B antibodies
(found on type O blood cells)
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Cholesterol and cholesterol esters
CH3
CH3
H
OH
H3C
HH
hydrophillic
hydrophobic
OR
O
usually palmitate
drawn this way
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STEROID NUMBERING SYSTEM
A B
C D1
2
3
45
6
7
89
10
11
12
13
14 15
16
17
18
19
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STEREOCHEMISTRY OF STEROIDSCH3 CH3H
H
H
H
CH3CH3
HH
H
H
H
H
CH3
OH
CH3
O
O
HO
H
H
H
CH3
H
CH3
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Cholesterol sources, biosynthesis
and degradation diet: only found in animal fat
biosynthesis: primarily synthesized in the liver fromacetyl-coA; biosynthesis is inhibited by LDL uptake
degradation: only occurs in the liver
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Cholesterol and cholesterol esters
HO
HH
H
O
HH
H
R
O
usually palmitate
The hydroxyl at C-3 is hydrophilic; the rest of the
molecule is hydrophobic; also 8 centers of asymmetry
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Cholesterol and cholesterol esters
HO
HH
Functions: -serves as a component of membranes of cells (increases or
moderates membrane fluidity
-precursor to steroid hormones
-storage and transportcholesterol esters
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Functions of cholesterol serves as a component of membranes of cells
(increases or moderates membrane fluidity)
precursor to steroid hormones and bile acids
storage and transport cholesterol esters
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Prostaglandins and other
eicosanoids (prostanoids) local hormones, unstable, key mediators of
inflammation
derivatives of prostanoic acid
COOH
20
8
12
prostanoic acid
9
1115
O
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O R
O
O
P
O
O
O-
X
O
COOH
CH3
phospholipase A2 (enzyme that hydrolyzes
at the sn-2 position - inhibit
indirectly by corticosteroids
H20
prostaglandin synthase
(also k nown as cyclooxygenase)
O
O
COOH
OH
very unstable
bond
PGH2
COX is inhibibited by
aspirin and other NSAIDs
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O
O
COOH
OH
PGH2
COOH
OH
O
HO
COOH
OHHO
HO
PGE2 PGF2akey mediator of inflammation
O
R1
O
R1
O
R1 R
HO
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R2 R2
PGA PGB
1
R2
PGC
R1
R2
O
PGD
R1
R2
O
HO
R1
R2
HO
HO
R1
R2
O
O
PGE PGFa PGG and PGHR2
HO
O
R1
R1
R2
O
PGJ
R1
R2
O
O
PGK
PGI
O
O
R1
R2 O
R1
R2HO
OH
TXA TXB
SUBSTITUTION PATTERN OF PROSTANOIDS
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Prostacyclins, thromboxanes and
leukotrienes PGH2 in platelets is converted to thromboxane A2
(TXA2) a vasoconstrictor which also promotesplatelet aggregation
PGH2 in vascular endothelial cells is converted toPGI2, a vasodilator which inhibits plateletaggregation
Aspirins irreversible inhibition of platelet COXleads to its anticoagulant effect
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Functions of eicosanoids Prostaglandins particularly PGE1 block gastricproduction and thus are gastric protection agents
Misoprostol (Cytotec) is a stable PGE1 analog that
is used to prevent ulceration by long term NSAIDtreatment
PGE1 also has vasodilator effects Alprostadil (PGE1) used to treat infants with
congenital heart defects Also used in impotance (Muse)
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Functions of eicosanoids PGF2a causes constriction of the uterus
Carboprost; Hebamate (15-Me-PGF2a) inducesabortions
PGE2 is applied locally to help induce labor at term
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Examples of drugs derived from prostaglandins
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C5H11
HS
Cys
gGlu
OH
COOH
LEUKOTRIENE F 4 (LTF4)
C5H11
HS
Cys
OH
COOH
Gly
gGlu
LEUKOTRIENE C 4 (LTC4)
Leukotrienes are derived from arachidonic acid via the enzyme5-lipoxygenase which converts arachidonic acid to 5-HPETE
(5-hydroperoxyeicosatetranoic acid) and subsequently by
dehydration to LTA4
peptidoleukotrienes
Leukotrienes
Leukotrienes
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C5H
11
HS
Cys
OH
COOH
LEUKOTRIENE E 4 (LTE4)
C5H11
HS
Cys
OH
COOH
Gly
LEUKOTRIENE D 4 (LTD4)
Leukotrienes are synthesized in neutrophils, monocytes, macrophages,
mast cells and keratinocytes. Also in lung, spleen, brain and heart.A mixture of LTC4, LTD4 and LTE4 was previously known as the
slow-reacting substance of anaphylaxis
peptidoleukotrienes
Leukotrienes
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C5H11
COOH
O
LEUKOTRIENE A 4 (LTA4)C5H11
HO
COOH
OH
LEKOTRIENE B 4 (LTB4)
Non-peptidoleuktrienes: LTA4 is formed by dehydration of
5-HPETE, and LTB4 by hydrolysis of the epoxide of LTA4
Leukotrienes
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Biological activities of leukotrienes
1. LTB4 - potent chemoattractent- mediator of hyperalgesia- growth factor for keratinocytes
2. LTC4 - constricts lung smooth muscle
- promotes capillary leakage1000 X histamine
3. LTD4 - constricts smooth muscle; lung- airway hyperactivity
- vasoconstriction4. LTE4 - 1000 x less potent than LTD4
(except in asthmatics)
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Leukotriene receptor antagonists
Montelukast
(Singulair)
Zafirlukast
(Accolate)
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Lipid-linked proteins Lipid-linked proteins (different from lipoproteins)
lipoproteins that have lipids covalently attached to them
these proteins are peripheral membrane proteins
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Lipid-linked proteins 3 types are most common:
Prenylated proteins
Farnesylated proteins (C15 isoprene unit)
Geranylgeranylated proteins (C20 isoprene unit)
Fatty acylated proteins
Myristoylated proteins (C14)
Palmitoylated proteins (C16)
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Lipid-linked proteins glycosylphosphatidylinositol-linked proteins (GPI-
linked proteins)
occur in all eukaryotes, but are particularly abundant in
parasitic protozoa located only on the exterior surface of the plasma
membrane
Fatty acylated proteins
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Fatty acylated proteins
Prenylated proteins
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y p
GPI-linked proteins
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Lipoproteins particles found in plasma that transport lipidsincluding cholesterol
lipoprotein classes chylomicrons: take lipids from small intestine through lymph
cells
very low density lipoproteins (VLDL)
intermediate density lipoproteins (IDL)
low density lipoproteins (LDL)
high density lipoproteins (HDL)
Terpenes
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Lipoprotein
class
Density
(g/mL)
Diameter
(nm)
Protein %
of dry wt
Phosphol
ipid %
Triacylglycerol
% of dry wt
HDL 1.063-1.21 515 33 29 8
LDL 1.019
1.063
1828 25 21 4
IDL 1.006-1.019 25 - 50 18 22 31
VLDL 0.951.006 30 - 80 10 18 50
chylomicrons < 0.95 100 - 500 1 - 2 7 84
Composition and properties of human lipoproteins
most proteins have densities of about 1.31.4 g/mL and lipid aggregates usually
have densities of about 0.8 g/mL
Lipoprotein structure
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Lipoprotein structure
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LDL molecule
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The apolipoproteins major components of lipoproteins often referred to as aproteins
classified by alphabetical designation (A thru E)
the use of roman numeral suffix describes theorder in which the apolipoprotein emerge fromachromatographic column
responsible for recognition of particle by receptors
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HELICAL WHEEL PROJECTION OF A PORTION OF
APOLIPOPROTEIN A-I
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LIPOPROTEINS spherical particles with a hydrophobic core (TG and
esterified cholesterol)
apolipoproteins on the surface large: apoB (b-48 and B-100) atherogenic
smaller: apoA-I, apoC-II, apoE
classified on the basis of density and electrophoreticmobility (VLDL; LDL; IDL;HDL; Lp(a)
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Apoproteins of human lipoproteinsA-1 (28,300)- principal protein in HDL
90 120 mg% in plasma
A-2 (8,700) occurs as dimer mainly in HDL 30 50 mg %
B-48 (240,000) found only in chylomicron
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Apoproteins of human lipoproteins C-1 (7,000) found in chylomicron, VLDL, HDL
4 7 mg %
C-2 (8,800) - found in chylomicron, VLDL, HDL
3 8 mg % C-3 (8,800) - found in chylomicron, VLDL, IDL, HDL
8 15 mg %
D (32,500) - found in HDL 8 10 mg %
E (34,100) - found in chylomicron, VLDL, IDL HDL 3 6 mg %
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Major lipoprotein classes chylomicrons
density
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Major lipoprotein classesVLDL
density >1.006
diameter 30 - 80nm
endogenous triglycerides
apoB-100, apoE, apoC-II/C-III
prebeta in electrophoresis
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Major lipoprotein classes IDL (intermediate density lipoproteins)
density: 1.006 - 1.019
diameter: 25 - 35nm
cholesteryl esters and triglycerides
apoB-100, apoE, apoC-II/C-III
slow pre-beta
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Major lipoprotein classes HDL (high density lipoproteins)
density: 1.063-1.210
diameter: 5-12nm
cholesteryl esters and phospholipids
apoA-I, apoA-II, apoC-II/C-III
alpha (electrophoresis)
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Major lipoprotein classes LDL (low density lipoproteins)
density: 1.019 - 1.063
diameter: 18-25nm
cholesteryl esters
apoB-100
beta (electrophoresis)
< 130 LDL cholesterol is desirable, 130-159 is borderlinehigh and >160 is high
Photograph of an arterial plaque
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The LDL receptor characterized by Michael Brown and Joseph
Goldstein (Nobel prize winners in 1985)
based on work on familial hypercholesterolemia
receptor also called B/E receptor because of itsability to recognize particles containing both aposB and E
activity occurs mainly in the liver
receptor recognizes apo E more readily than apo B-100
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Representation of the
LDL receptor
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Terpenes simple lipids, but lack fatty acid component
formed by the combination of 2 or more moleculesof 2-methyl-1,3-butadiene (isoprene)
monoterpene (C-10) made up of 2 isoprene units
sesquiterpene (C-15) made up of 3 isoprene units
diterpene (C-20) made up of 4 isoprene units
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Monoterpenes
limonene
CHO
citronellal
OH
menthol camphene
Monoterpenes are readily recognized by their characterisitic flavors
and odors ( limonene in lemons, citronellal in roses and geraniums,
pinene in turpentine and menthol from peppermint
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Sesquiterpenes
bisabolene
HO
eudesmol
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Diterpenes
CH 2OH
HO
H
H
OH
COOHC
O
CH 3
O
phytol gibberelic acid
CH 3 CH 3H3C
CH 3
CH 3
O
H
All-trans-retinal
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Triterpenes
Triterpenes are C-30 compounds are addition products of 2 sesquiterpenes;
Both squalene and lanosterol are precursors of cholesterol and other steroids
HO
H
squalene lanosterol
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Other terpenes tetraterpenes (C-40) are not as common as mono,
di, and triterpenes include the carotenoids such as beta-carotene
(precursor of vitamin A) and lycopene found in
tomatoes usually colorful compounds due to highly conjugated
system
polyisoprenoids or polyprenols consist of
numerous isoprene adducts (8 22) examples include dolichol phosphate, undecaprenylalcohol (bactoprenol) and the side chains of vitamins K,
vitamin E and coenzyme Q