science fair project - mans · define lipids. describe the biological importance of lipids. point...
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Lipid ChemistryPresented By
Ayman Elsamanoudy
Salwa Abo El-khair
4
1. By the end of this chapter the student should be able to:
define lipids.
describe the biological importance of lipids.
point out basic lipid chemistry.
classify lipids.
explain the chemistry and main function of simple, compound
and derived lipids.
2. By the end of this chapter the student should be able to
apply biochemical knowledge on analyzing biochemical bases of
the diseases through case study.
3
Objectives:
Compound Lipids
Compound Lipids
Compound (conjugated) lipids are lipids
conjugated with other substances.
They include:
Phospholipids :
(lipid+ phosphoric acid + nitrogenous base).
Glycolipids :(lipid + carbohydrate).
Sulpholipids :(lipids + sulphate).
Lipoproteins :(lipid + protein).
Phospholipids They are a group of compound lipids formed of:
Alcohol &Fatty acids
+
Phosphoric acid
+
Nitrogenous base (may be).
They are classified according to the alcohol into:
Phosphoglycerides
Sphingomyelin
Phosphoglycerides
In which nitrogen phosphorous ratio (N/P
ratio =1) is 1
i.e. they contain one nitrogen and one
phosphate.
Sphingomyelin
in which N/P ratio is 2
i.e. it contains 2 nitrogen and one phosphate.
A- Phosphoglycerides
Phosphoglycerides are a group of phospholipids
containing glycerol with N/P ratio = 1.
They include:
Phosphatidic acid
Lecithin,
Cephalins,
Phosphatidyl inositol
Plasmalogen
Cardiolipin.
1- Phosphatidic acid
It is phosphoric acid ester of diglycerides.
Structure:
Glycerol.
Saturated fatty acid , attached to α carbon of
glycerol by ester bond.
Unsaturated fatty acid, attached to β carbon of
glycerol by ester bond.
Phosphoric acid attached to α carbon of glycerol
by ester bond.
Function of phosphatidic acid
It is an intermediate compound
in biosynthesis of other
phosphoglycerides and triglycerides
2- Lecithin
It is phosphatidyl
choline.
It is formed of:
Glycerol.
Saturated fatty acid,
Unsaturated fatty acid,
Phosphoric acid,
Choline attached to
phosphoric acid by ester
bond.
This means :phoshatidic
acid + choline base
Function of lecithin
1. It is the most abundant phospholipids in the
cell membrane.
2. It acts as a lipotropic factor
(substances that prevent accumulation of lipids
in the liver).
3. Dipalmityl lecithin acts as Lung surfactant
(substances that line the lung alveoli forming a
layer at the interface of fluid lining the
alveoli and air inside alveoli preventing lung
collapse).
Respiratory Distress Syndrome (RDS)
Incidence :In premature infants .
Causes : the lung alveoli don’t secrete sufficient
amount of lecithin.
Effect : lung collapse.
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Lysolecithin
Snake venom contains
lecithinase enzyme,
which removes the unsaturated fatty acid from
lecithin forming lysolecithin.
Lysolecithin is a strong surface- active
substance that has a marked haemolytic action
causing haemolysis of the red blood cells.
Lysolecithin
Cephalins
They are phosphatidyl ethanolamine & phosphatidyl serine
Structure
They are formed of:
Glycerol.
Saturated fatty acid
Unsaturated fatty acid,
Phosphoric acid.
Ethanolamine or serine.
CH
CH
CH
O
O
O
COR1
COR2
HPO4 CH2 CH2 NH2 CH2 CH2 NH2Ethanolamine
CH
CH
CH
O
O
O
COR1
COR2
HPO4 CH2 CH COOH
NH2
CH2 CH COOH
OH NH2Serine
phosphatidyl ethanolamine
phosphatidyl serine
Phosphoglycerides3- Cephalins
HO
HO
Phosphatidyl-serine
Phosphatidyl-ethanolamine 17
Function of cephalins
They have a role in blood coagulation.
They accelerate blood clotting because they
share in the structure of thromboplastin, which
is essential for blood clotting.
4- Phosphatidyl inositol (lipoinositol).
Structure
It is formed of: Glycerol.
Saturated fatty acid,
Unsaturated fatty acid,
Phosphoric acid
Inositol, which is a cyclic alcohol derived from glucose.
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CH2
C HO
CH2
C
O P
R2
O
-Phosphatidylinositol
O
OH
O
C R1
O
O
H
H
OH
OH
HOH
H
OHOH
H H
1
2 3
4
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Function of phosphatidyl inositol:
It is found in brain tissue.
It has a role in mechanism of hormone action.
on hydrolysis by phospholipase C enzyme, it gives
compounds that acts as second messengers in
hormone action e.g. diacyl glycerol (DAG) and
inositol triphosphate (IP3).
5- Plasmalogens:
Structure
It is formed of:
Glycerol.
(unsaturated alcohol) at
α position. (fatty aldehyde
in the enol form)
Unsaturated fatty acid at β position.
Phosphoric acid.
Nitrogenous base, which may be choline, ethanolamine or
serine.
SO, They are lecithin or cephalin in which the fatty acid
attached to α carbon is replaced by unsaturated alcohol .
Function of plasmalogens
They are present in cardiac muscle, skeletal
muscles and brain.
6- Cardiolipin
It is a diphosphatidyl glycerol formed of 2
phosphatidic acids attached together by
glycerol.
CH2
C HO
CH2
C
O P
R2
O
Cardiolipin
O
OH
O
C R1
O
O
CH2
CH OH
CH2
CH2
CH O
CH2
C
OP
R3
O
O
OH
O
CR4
O
O
Structure of Cardiolipin
It is formed of: 3 glycerol molecules.
2 saturated fatty acids.
2 unsaturated fatty acids.
2 molecules of phosphoric acid.
Functions of cardiolipin
Cardiolipin is present in heart muscle.
It is used as antigen for detection of syphilis.
B- Sphingomyelins
Sphingomyelin is a phospholipids with N/P ratio
= 2.
sphingomyelin contains sphingosine base (18 C).
It is called Sphingol ; long chain unsaturated
amino alcohol) instead of glycerol.
Sphingolipids
Ceramide
It is formed of sphingosine base to which fatty acid is
attached by amide linkage.
Structure of sphingomyelin
Sphingosine base.
Unsaturated fatty acid (to the amino group of
sphingosine by amide link).
Phosphoric acid (to the primary alcoholic group of
sphingosine by ester bond ).
Choline base attached to phosphoric acid by ester
bond .
Sphingomyelin
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Function sphingomelin
It is abundant in the nervous system in the myelin
sheath .
It is present to lesser extent in liver, spleen and bone
marrow.
N.B: Nimann Pick disease
It is a disease caused by deficiency of
sphingomelinase enzyme, which catabolizes
sphingomyelin.
This leads to accumulation of large amounts
of sphingomelin in liver, spleen and brain.
Sphingophospholipidsphosphoglycerides
Sphingosine base
(sphingol alcohol)Glycerol Alcohol
-One
-( usually long
unsaturated )
-linked by amide link
-2FA
-(at α position is saturated &
at β is unsaturated )
-linked by ester bond
Fatty acids
One One Phosphate group
Choline base Differ according to the type Nitrogenous Base
21N/P ratio
Negative Positive Acroline test
SphingomyelinePhosphatidic acid ,lecithen,
cephalines,plasmalogen and
cardiolipin
Types
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Lipid ChemistryPresented By
Ayman Elsamanoudy
Salwa Abo El-khair
5
Glycolipids
They are compound lipids
(carbohydrates +lipids).
They contain sphingosine base
They include cerebrosides and gangliosides.
1- Cerebrosides
They are called cerebrosides because they are
present mainly in the brain and nerves.
Cerebrosides Structure
Sphingosine base.
Long chain fatty
acid attached to
the amino group
of the sphingosine
base by amide linkage.
Carbohydrate usually
galactose but may be
glucose.
According to the fatty acid present,
Cerebrosides are classified into:
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OxynervonnervonCerebronkerasin
Hydroxy-
nervonic acid
Nervonic acid Cerebronic
acid
Lignoceric
acid
FA
24242424Number of
its C-
atoms
Monounsaturated Monounsaturated Saturated SaturatedDegree of
saturation
hydroxy FANon hydroxy
FA
hydroxy
FA
Non
hydroxy FA
Hydroxyl
group
Functions of cerebrosides
1. They are present mainly in the nervous
tissues i.e. brain and nerves.
- They act as electric insulators of nerve
impulses.
2. Also, they are present in spleen, liver,
adrenal gland, kidney and lungs.
2- Gangliosides
These are the most complex glycolipids.
Structure
Sphingosine base.
Long chain fatty acid.
One glucose molecule.
2 galactose molecules.
N-acetyl galactosamine.
N-acetyl neuraminic acid (siailic acid; NANA).
Function
Gangliosides are present in high concentration in brain.
They act as receptors at cell membrane.
Lipid part
CHO part
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Sulpholipids
They are cerebrosides containing sulphate group
attached to C3 of galactose.
Structure:
Sphingosine base.
Long chain fatty acid (attatched to the amino
group of the sphingosine base).
Carbohydrate usually galactose but may be
glucose.
Sulphate group (attatched to C3 of galactose).
Structure of supholipids
• Function
• They are
present in
brain and
nervous
tissues.
Structure of galactosylceramide (galactocerebroside, R
= H), and sulfogalactosylceramide (a sulfatide, R =
SO42- )
Lipoproteins
These are compound lipids formed of :
lipid part (triglycerides, cholesterol or
phospholipids) &
protein part (α or β globulin).
Function of lipoproteins:
In the structure of cell membrane.
Lipid transport in the blood (Lipids are insoluble in
water). Lipids bind to protein to make lipoproteins
water-soluble to be transported in the blood.
• Each contains different
kinds and amounts of
lipids and proteins
– The more protein,
the higher the
density
– The more lipid, the
lower the density
• Each has different
function
Lipoproteins
Hydrophobic lipids
Amphiphilic lipids
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Structure of lipoprotein
Hydrophobic lipids (TG, CE) in the core
Amphiphilic lipids (C, PL) and proteins on the surface
Separation of lipoproteins
Lipoproteins can be separated by:
1- Ultracentrifugation
In NaCl solution, lipoproteins are separated by
ultracentrifugation, as they differ in the degree of
floatation, into :
chylomicrons, VLDL, LDL and HDL.
2- Electrophoresis
As they differ in migration rate due to differences in
molecular weight and charge, lipoproteins are
separated into :
chylomicrons, pre β, β and α lipoproteins.
3- Chromatography
According to
ultracentrifugation
-Chylomicrons,
-Very low-density
lipoproteins
-Low-density
lipoproteins
-High-density
lipoproteins
According to
electrophoresis:
-Chylomicrons,
-Pre-β lipoproteins,
-β lipoproteins,
-α lipoproteins.
Lipoproteins
Anode
+
Cathode
---
α lipoproteins Pre-β lipoproteins β lipoproteins Chylomicrons
(HDL) (VLDL) (LDL)
LipoproteinsChylomicrons VLDL
Site of synthesis
Small intestine Liver
Structure Mainly triglycerides, small amount of cholesterol, phospholipids and protein
Mainly triglycerides, greater amount of cholesterol, phospholipids and protein
Lipoproteins
LDL HDL
Site of synthesis
Liver
Blood
Liver
Structure Mainly cholesteroland good amount of proteins, phospholipids and triglycerides
Mainly proteinsand phospholipids, small amount of cholesterol and little amount of triglycerides
Chylomicron VLDL LDL HDL
Size Largest Large Small Smallest
Rate of float-ation
Highest High Low Lowest
Electro-phoresis
Do not migratebecause of their highcontent of triglycerides (have high molecular weight and no charges).
Migrate after β globulin
Migrate with β globulin
Migrate with α globulin
Chylomicron VLDL
Function Transport exogenous triglycerides from the small intestine to tissues.
Transport endogenous triglycerides from the liver to tissues.
LDL HDL
Function Transport cholesterol from the liver to tissues.
Retrograde transport of cholesterol from the tissues to liver.
Transport phospholipids from the liver to tissues.
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HDLLDLVLDLChylomicron
Mainly in LiverBloodLiverSmall intestineSite of
synthesis
Very smallSmallLargeLargestSize
Mainly of
proteins and
phospholipids,
small amount of
cholesterol and
little amount of
triglycerides
Mainly
cholesterol and
appreciable
amount of
proteins,
phospholipids
and triglycerides
Principally
triglycerides,
greater amount of
cholesterol,
phospholipids
and protein
Mainly triglycerides,
small amount of
cholesterol,
phospholipids and
protein
Structure
Transport
from cholesterol
the tissues to the
liver (reverse
cholesterol
transport
Transport
from cholesterol
the liver to the
tissues.
Transport
endogenous
from triglycerides
the liver to the
tissues
exogenous Transport
from triglycerides
the small intestine to
the tissues.
Functions
Lowest Low High Highest Rate of
floatation
Migrate with α
globulin
Migrate with β
globulin
Migrate before β
globulin
Do not migrate Electrophore
sis
Activity 1- Give the hydrolytic products of the followings:
1-Lecithen
2- Cephalins
3- Cardiolipis
2-Compare between each of the followings :
1-Phosphoglycerides& sphingophospholipids
2-Chylomicron and HDL.
3- cerbrosides and gandliosides
3- enumerate the types of lipoproteins & mention the
main function of each of them 61
4-Enumerate:
1-lipids that contain choline base.
2- lipids that contain sphingol alcohol.
3-lipids that contain galactose sugar.
4- Methods of separation of lipoproteins
5- what is the type of bond in each of the following:
1- TAG
2-Ceramide.
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Choose the best correct nswer
Ceramide is a constituent of the following EXCEPT:
a) cerebroside
b) sulfatides
c) sphingomyelins
d) lecithen
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11/17/2014 64Ahmed A.Albadry
GREAT
THANKS
Ayman Elsamanoudy
Salwa Abo El-khair