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Lipids
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Lipids
Organic compounds present in living
organisms, insoluble in water but able to be
extracted by organic solvents such as:
chloroform, acetone, benzene.
Extraction = the process of obtaining something from a mixture or compound
by chemical or physical or mechanical means
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Biologic role of lipids
As a building material for all membrane-like structures in
cells (phospholipids, cholesterol, glycolipids).
Have decisive role in dynamic processes of cell
membrane. Influence on fluidity, asymmetry, permeability,
enzymatic activity and receptor properties (fosfolipids,
cholesterol, fatty acid).
Steroid hormon precursor (cholesterol) and tissues
hormons (fatty acids).
Take part in immunological phenomena (eikozanoids)
[eicosanoids are signaling molecules made by oxidation of twentycarbon essential fatty acids]
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Lipids categories (according to Bloor)
I. Simple lipids: esters of fatty acids with various alcohols
a. Fats: esters of fatty acids with glycerol
b. Waxes: esters of fatty acids with higher molecular
weight monohydric alcohols
c. Sterols
II. Complex lipids : esters of fatty acids containing groups
in addition to alcohol and fatty acids.
a. Phospholipids
b. Glycolipids
c. Other complex lipids
III. Precursor and derived lipids
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Lipids categories (according to Bloor)
III. Precursors and lipids derivatives
a)
b)
c)
d)
e)
f)
g)
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fatty acids,
glycerol,
alcohols different than glycerol
sterols,
carbohydrates
vitamins soluble in fats
hormons
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FATTY ACIDS
STRUCTURES AND PROPERTIES
Monocarboxylic acids with hydrocarbon chains with different
amount of carbon atoms: 4 to 30.
Depends on carbon quantities they have different name:
1. Short-chain (<6 atoms C) fatty acids
2. Average- chain (8 – 14 atoms C) fatty acids
3. Long-chain (> 16 atoms C) fatty acids
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Hydrocarbon chain of fatty acid is hydrophobic.
Carboxylic group of fatty acids is hydrophilic.
CH3(CH2)7CH=CH(CH2)7COOH
Oleic acid (unsaturated)
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CH3(CH2)16COOH
Stearic acid (saturated)
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FATTY ACIDS
FUNCTIONALITY
Reserve (store) role in adipocyts – (cell which
stores synthesized fats)
Structural role in membrane cells
Take place in covalent modification of proteins
In protein – play role as a hydrophobic anchor
Energy material
Derivatives of 20-carbon atoms acids are
hormones.
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FATTY ACIDS
STRUCTURE and PROPERTIES
Saturated fatty acids contain over 10 carbon atoms in
chain.
are solids
are insoluble in water
melting point increases with length of the chain
Unsaturated fatty acids in room temperature are usually
liquids.
Fatty acid’s salts with alkali metals are well soluble in water but
magnesium and calcium salts are almost insoluble.
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FATTY ACIDS
STRUCTURE and PROPERTIES
Characteristic reactions of unsaturated fatty acids:
Hydration:
– CH = CH – + H2O
– CH(OH) – CH2 –
Reduction:
– CH = CH – + XH2
reduction
– CH2CH2 – + X
Oxidation:
oxidation
R1 – CH = CH –R2
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R1 – CHO + R2 – CHO
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FATTY ACIDS
STRUCTURE and PROPERTIES
Presence of unsaturated, double bond allows unsaturated fatty acids to
posses two stereo-isomeric structures : cis and trans
Oleic acid
Elaidic acid
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FATTY ACIDS
Nomenclature
• Common names have their names from the place where
they were discovered or where they can be found
• Systematic names are from Greek numbers with following
endings:
- anoic for saturated acids
- enoic for unsaturated acids
Octadecanoic acid
Stearic acid
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9,12 octadecadienoic acid
Linoleic acid
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FATTY ACIDS
Nomenclature
• Systematic names are from Greek numbers
• Location of unsaturated, double bond are indicated by ∆ (delta))
follow by the number of carbon atom with double bond .
Νumber of carbon atoms participating in double bonds are counted
starting from carbon atom in carboxylic group. Letters n lub ω
indicate double bond location, starting from the methyl group.
ω
Fatty acid with cis ∆-9 bond
CH3
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UNSATURATED FATTY ACIDS
Common
name
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Systematic
name
Abbreviated
name
Chemical structure
Oleic
9 – octadecenoic
18:1 ∆ 9
18:1 (n-9)
CH3(CH2)7CH=CH(CH2)7COOH
Eikoseic
9 - eicosenoic
20:1 ∆ 9
CH3(CH2)9CH=CH(CH2)7COOH
Erucic
13 doeicosenoic
22:1 ∆ 13
CH3(CH2)7CH=CH(CH2)11COO
H
Linoleic
9,12 octadecadienoic
18:2 ∆ 9,12
18:2 (n-6)
CH3(CH2)4(CH=CHCH2)2(CH2)6
COOH
Linolenic
9,12,15 octadecatrienoic
18:3 ∆ 9,12,15,
18:3 (n-3)
CH3CH2(CH=CHCH2)3 (CH2)6
COOH
Arachidonic
5,8,11,14 eikosanoic
20:4 ∆ 5,8,11,14,
20:4 (n-6)
CH3(CH2)4(CH=CHCH2)4 (CH2)2
COOH
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FATTY ACIDS
NECESSARY UNSATURATED FATTY ACIDS
There are 3 “families” of these acids: omega-3, omega-6 and omega-9
Human organism is able to place double bond only in position 9 counting
from methyl group.
Precursor of omega acids with bonds between position 3 and 6 must be
delivered to organism with food.
Source of unsaturated fatty acids :
- vegetable oils, soy, corn oil
- animal phospholipids
Polyunsaturated fatty acids from omega family, with 5 and 6 double bonds
are in large quantities in fish oils.
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ACYLGLYCEROLS
Because of their chemical structure they belong to
esters of glycerol and fatty acids
Alcohol component– glycerol
Acid component – monocarboxylic higher fatty acids
Most often they are mixtures of triglycerols of various
fatty acids.
Glycerol has attached through ester bond one, two or
three fatty acids. Usually, at each carbon atom from
glycerol, different fatty acid is attached.
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Acyl Fats (acylglycerols)
Glycerol
H2C – OH
HO – C – H
H2C – OH
C1
α
sn-1
C2
β
sn-2
C3
α
sn-3
In acylglycerols secondary hydroxyl group is located on the left side
of carbon atom
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Acyl Fats (acylglyceroles)
Glycerol
Triacylglycerol
O
H2C – OH
HO – C – H
H2C – OH
O
H2C – O – C – R1
R2 – C – O – C – H
H2C – O – C – R3
O
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Phospholipids
Phosphatidic acid
Phospholipids are built from four components:
Glycerol
Two acyl group connected by ester bond (with C1and C2 from
glycerol)
Phosphate connected by ester group (with C3 from glycerol)
Other alcohol (choline, ethanoloamine, serine, glycerol),
connected with -OH group from phosphate
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Phospholipids
+ )
Phosphatidic acid + HO – CH2 – CH2 – N(CH
3 3
(choline)
R` - palmitic acid
R” – oleic acid
Phosphatidylcholine (lecithin)
Phosphatidic acid + ethanolamine
Phosphatidylethanolamine
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Sphingophospholipids
• Sfingophospholipids are long chain amids of fatty acids
and sphingosine which additionally are containing
choline.
• Are composed from:
sphingosine – long chain,monosaturated dihydroxyl
aminoalcohol
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long chain fatty acid
phosphate
Choline
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Sphingophospholipids
sphingosine
+
unsaturated
fatty acid
ceramide (N- acylsphingosine)
+ choline
+ H3PO4
Sphingomyelin
( good isolator for nerve tissues)
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Glycolipids
Contain:
ceramide
sugar molecule (one or more)
galactosylceramide
glucosylceramide
(cerebroside)
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Gangliosides
Glucosylceramide derivative containing one or
several groups of sialic acid (amphipatic)
Sialic acid
Ganglioside GM1
There are different from cerebroside that instead of monosugar they
contain oligosaccharide.
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Isoprenoids, steroids and derivatives
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http://www.iupac.org/didac/
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isopren (2-methyl-1,3 butadien)
Isopentenyl pyrophosphate
(IPP)
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3,3-dimethylallyl pyrophosphate
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Cholesterol
• cholesterol belongs to steroids
and contains 6 isoprene units
• It’s precursor of all steroid
hormones
• Component of cells and
membranes
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Synthesis of cholesterol
squalene
lanosterol
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sterane
cholesterol
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Cholesterol
Exists in all membrane’s cells in mammalia:
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In estrified form
In a free form
It is 10% -15% of dry weight of brain
It is substrate for hormone synthesis
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Sterane
Structure:
C
A
D
B
cyklopenthanperhydrophenantrene
three rings of cyklohexane
and one ring of cyklopenthane= 4
rings
Component of:
cholesterol
steroid hormones
bile acids
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Sterane structure
5- α- hydrogen
trans
5-β- hydrogen
cis
Hydrogen bond at C5
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Sterane structure
5- α- hydrogen
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5-β- hydrogen
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Bile acids
Are synthesized from cholesterol in the liver
Insuficient amount of vit. C can disturb synthesis of bile acid which
can leads to vein’s sclerosis
Contain 1 to 3 hydroxyl groups attached to the ring
Contain carboxyl group in side chain
Are amphipatic (hydrophilic and hydrophobic)
Can decrease surface tension of water
They are good emulsifier
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Cholic acid (bile acid)
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The End
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