Download MBBS Biochemistry PPT 4 L5 Phospholipids Lecture Notes

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Study Of

Compound Lipids

Compound Lipids

? Compound lipids are class of

Lipids

? Chemically Esters of Fatty acids

with Alcohols attached with

Additional groups.
? Additional Groups in Compound Lipids may

be either of these:

?Phosphoric acid
?Nitrogenous Base
?Carbohydrate moieties
?Proteins
?Sulfate groups

3 Main Compound Lipids

?Phospholipids
?Glycolipids
?Lipoproteins


Phospholipids

Phospholipids

? Compound Lipids

? Components:

? Alcohol- Glycerol/Sphingol
? Fatty Acids- PUFAs and SFAs
? Additional Group- Phosphoric acid and Nitrogenous

/Non Nitrogenous moiety

? Nature- Amphipathic
? Phospholipids (PL) Chemical y Possess:

?Fatty acids esterified to Alcohol and

?Phosphoric acid attached with

Nitrogenous /non nitrogenous base.

Types Of

Phospholipds

Based upon Alcohol

Present in Phospholipid structure
? Two Types of Phospholipids are :

?Glycerophospholipids:

Glycerol containing Phospholipids

?Sphingophospholipids:
Sphingosine/ Sphingol containing

Phospholipids.

Glycerophospholipids/

Glycerophosphatides


Names & Structures

OF

7 Glycerophospholipids

Simplest Glycerophospholipid

PHOSPHATIDIC ACID


? Depending upon Nitrogenous and Non

Nitrogenous moiety attached.

? Examples of 7 Glycerophospholipids are:

1. Phosphatidic Acid (Simplest PL)
2. Phosphatidyl Choline (Lecithin)
3. Phosphatidyl Ethanolamine (Cephalin)
4. Phosphatidyl Serine (Cephalin)
5. Phosphatidyl Inositol/ Lipositol
6. Phospatidal Ethanolamine/ Plasmalogen
7. DiPhosphatidyl Glycerol /Cardiolipin
Phosphatidic Acid

? Phosphatidic acid is a simplest

Glycerophospholipid.

? Phosphatidic acid has Glycerol esterified

with two Fatty acids at C1 and C2 .

? C3 is esterified with Phosphoric acid.

? Phosphatidic acid serve as a

precursor for biosynthesis of

other Glycerophospholipids

? Either by linking of

?Nitrogenous or
?Non nitrogenous base


Phosphatidyl Choline/Lecithin


? Phosphatidyl Choline (Lecithin) is

most commonest and abundant

Glycerophospholipid in body.
? Phosphatidyl Choline is commonly called

as Lecithin.

? Derived from word `Lecithos' meaning

Egg Yolk.

? Phosphatidic acid is linked to a

Nitrogenous base Choline to form

Phosphatidyl Choline.

Cephalins

?Type of Glycerophospholipids
?Nitrogen base is Ethanolamine

or Serine.

?Phosphatidylethanolamine and

Phosphatidylserine are

Cephalins.


Phosphatidyl Ethanolamine


Phosphatidyl Serine
? An Amino acid Serine

linked to Phosphatidic acid

forms Phosphatidyl Serine.

Phosphatidyl Inositol/ Lipositol


Phosphatidyl Inositol Tri Phosphate

(PIP3)
? Inositol/Myo Inositol a Polyol

derived from Glucose

? Non Nitrogenous ,

Carbohydrate Derivative.

? Inositol linked to Phosphatidic

acid forms Phosphatidylinositol.

? Phospahatidyl Inositol 3,4,5 Tri

Phosphate (PIP3) in presence of

enzyme Phospholipase C

? Generates Diacyl Glycerol and

Inositol Tri Phosphate.


Phosphatidalethanolamine/

Plasmalogen
? Plasmalogen possess an Ether

linkage at C1.

? Fatty acid is linked to C1 of

Glycerol, by an Vinyl(CH=CH2)

Ether (C-O-C)linkage instead of

usual Ester bond.

? Nitrogen base linked are

Ethanolamine/Choline.

Diphosphatidylglycerol/

Cardiolipin


Di Phosphatidyl Glycerol
? Cardiolipin was first isolated from

Cardiac Muscles of Calf and hence

the name derived.



? Diphosphatidylglycerol/Cardiolipin is

chemically composed of

? Two molecules of Phosphatidic acid

linked to one Glycerol .



SphingoPhospholipids/

Sphingophosphatides



? Sphingomyelin is an example

of Sphingophospholipid.

? Sphingophospholipid is

Sphingosine based Lipid

? Which has Sphingosine linked

with Fatty acid-Phosphate

and Choline.
? Sphingosine is linked with a Fatty

acid by an amide linkage to form

Ceramide.

? Ceramide is then linked to

Phosphoric acid and Choline to

form Sphingomyelin.

Properties Of Phospholipids


Amphipathic Nature Of PL

? Phospholipds are Amphipathic/

Amphiphil ic in nature.

? Since the structure of PL possess

both polar and nonpolar groups.


? Hydrophilic/Polar groups of

Phospholipids:

?Phosphoric acid
?Nitrogenous groups

? Hydrophobic/non polar groups

of Phospholipids :

?Fatty acid/Acyl chains

Exogenous And Endogenous Sources

Of Phospholipids
Occurrence And Distribution Of

Phospholipids

? Various types of Phospholipids

Associated to al over body cel s.

? Most predominantly associated to

Biomembranes

? Myelin Sheath
? Alveoli in Lungs
Functions Of Phospholipids (PL)

1. Biomembrane Components
2. Lung Surfactant
3. Lipid Digestion and Absorption
4. LCAT activity for Cholesterol Esterification and Excretion
5. Lipotropic Factor
6. Clotting Mechanism
7. Cardiolipin role
8. Coenzyme Role
9. Choline from Lecithin Methyl Donor
10. Detoxification role of Lecithin
11. Eicosanoids biosynthesis
12. Nerve Impulse Conduction
13. Second Messenger of Hormone Regulation


Glycerophospholipid Functions

Lecithin Is Most Functional Phospholipid


1. Phospholipids Components Of

Biomembranes

Phospholipid Bilayer of

Plasma membrane


Cholesterol intercalates among Phospholipids.
Cholesterol fills in the spaces left by the kinks of

PUFAs .
Cholesterol stiffens the bilayer and makes membrane

less fluid and less permeable.


? Role Of Lecithin

? The Glycerophospholipid Lecithin is

the major structural components of

biomembranes.

? An Amphipathic phospholipid bilayer

has polar head groups of PL directed

outwards.
? Membrane Phospholipid bilayer

,constituent of cel membranes

imparts:

?Membrane Structural Integrity

?Membrane Fluidity

?Membrane Flexibility

?Selective Permeability

? Phospholipids may have fatty

acids which are saturated or

unsaturated.

? This affects the properties of

the resulting bilayer/cel

membrane:
?Most membranes have

phospholipids derived from

unsaturated fatty acids.

?Unsaturated fatty acids add

fluidity to a bilayer since

`kinked' tails do not pack

tightly together.

? Phospholipids (PL) derived from unsaturated

phospholipids al ow faster transport of

nonpolar substances across the bilayer.


? Polar substances are restricted to cross

the membrane .

? PL bilayer in membranes protect the cel

from an entry of polar reactive and

interfering substances and serve as

security guards of cel s.
? Membranes of Nerve cel s, which

are stiffer contain a much higher

percentage of phospholipids

derived from saturated fatty acids.

? They also contain high levels of

Cholesterol which stiffens

membrane structure.

2.Phospholipid As Lung Surfactant


? DiPalmitoyl Phosphatidyl Choline serve

as an Lung surfactant.

? It Lowers surface tension and keeps

Alveoli of lungs blown. (prevent

adherence of alveoli)

? Enables effective exchange of gases

(Oxygen) in Lungs.


? After expiration of air the

alveoli gets deflated.

? The lung surfactant reduces

the surface tension and al ow

the alveolar wal s to

reinflate.


?Phospholipid as Lung

surfactant

?Prevent body to suffer

from Respiratory Distress

Syndrome (RDS).
3.Phospholipids

Help In Digestion And Absorption Of

Dietary Lipids

? Phospholipids being amphipathic

in nature act as good emulsifying

agents.

? Along with Bile Salts they help in

digestion and absorption of non

polar dietary Lipids.
4.Phospholipid Lecithin

Helps In Cholesterol Excretion


? Lecithin helps in Cholesterol

Esterification by LCAT activity.

? Cholesterol Ester is later

dissolved in Bile and further

excreted it out.


? Lecithin serve as a storage depot

of Choline.

? Choline is a store of labile Methyl

groups

? Hence Choline participate in

Transmethylation reactions .

? Choline is used for generation of

neurotransmitter `Acetyl Choline"

which helps in nerve impulse

transmission.

? Choline serve as Lipotropic factor

hence helps in Lipoprotein formation in

Liver to mobilize out Lipids and prevent

from Fatty Liver.
6. Phospholipids Releases

Arachidonic Acid For Eicosanoid

Biosynthesis

? Lecithin at 2nd carbon has

Arachidonic acid (PUFA).

? It donates Arachidonic acid which

is a precursor for Eicosanoid

biosynthesis.
? Phosphatidyl Inositol also

provides Arachidonic acid for

Eicosanoids biosynthesis.

?Lecithin helps CYT450

system for drug

detoxification.
8. Phospholipids Has Role

In Blood Coagulation

? Role Of Cephalin

? Phosphatidyl Ethanolamine has

role in blood coagulation.

? It converts clotting factor

Prothrombin to Thrombin by

factor X.
? Phosphatidyl Serine has role

in Apoptosis (Programmed

Cel death).

10.Role Of Phospholipids In

Hormonal Action

Mediates Cel Signal Transduction


? Role Of Phosphatidylinositol

? Phosphatidyl Inositol

Triphosphate (PIP3) is a

constituent of cel membrane

? It mediate hormone action /cel

signal transduction and maintain

intracel ular Calcium.
? Inositol tri phosphate and Diacylglcerol

are released from PIP3 by membrane

bound Phospholipase C

? The Inositol triphosphate and DAG

serve as second messenger to hormones

Oxytocin and Vasopressin.

?Plasmalogen

associated to brain and

muscles helps in Neural

functions.
? Role Of Cardiolipin

? Cardiolipin is rich in inner

mitochondrial membrane and

supports Electron Transport

Chain and cellular respiration.

? Cardiolipin exhibits

antigenic properties and

used in VDRL serological

tests for diagnosis Syphilis.
? Phospholipid serve as Coenzyme

for certain Enzymes :

?Lipoprotein Lipase
?Cytochrome Oxidase

Functions OF Sphingophospholipids


? Sphingomyelins are rich in

Myelin sheaths which surrounds

and insulate the axons of

neurons.

? Sphingomyelin helps in nerve

impulse transmission.
Disorders Related To Phospholipids

? Respiratory Distress Syndrome

(RDS)

? Suffered by premature born infants.
? Caused due to deficiency of Lung

surfactant DiPalmitoyl Phosphatidyl

Choline.


? Since Lung is last organ to mature.

? Premature babies has insufficient lung

surfactant lining in the alveoli walls.

? Which supports no normal respiration.

? Has respiration difficulties due to

alveolar col apse.
?Signs And Symptoms Of

RDS

?Low ATP production

?Weakness ,Lethargy

?Low Cellular Functions

?Poor Coordination

Lecithin/Sphingomyelin (L/S) Ratio

of Amniotic Fluid

Assessment Of Fetal Lung Maturity

And

Diagnostic Criteria For RDS


? Lecithin /Sphingomyelin (L/S)

ratio of amniotic fluid, col ected

by Amniocentesis is a good

indicator to evaluate fetal lung

maturity.

? Prior to 34 weeks of gestation the

concentration of Lecithin and

Sphingomyelin in amniotic fluid is

equal.

? In Later weeks of gestation the

Lecithin levels are markedly increased.
? At ful term L/S ratio is > 2/>5

? In pre term infants L/S ratio

is 1.5 or < 1 results to suffer

from RDS.

OTHER RDS Sufferers

Individual with Lung Damage and

Dysfunctions

? Old aged Persons
? Smokers
? Severely Infected Lungs
? Lungs toxicated and damaged by chemicals


? Old age persons and Adults with

Lung damage

(Due to Smoking/ Infections)

? Who unable to biosynthesize the

lung surfactant may also exhibit

RDS.


Prevent And Manage RDS

? Pregnant Women Diet for biosynthesis of L and S

? Pregnant Women Activities and Positions

? Prevent Damaging Environment Exposures


Membrane Related Disorders

Due To Defective Phospholipds

Multiple Sclerosis Due to Defect In

Sphingomyelins and Myelin Sheaths


Defect In Sphingomyelins

May Affect

Nerve Impulse Conduction

Membrane Carbs,Lipids and Proteins

Structural y Important For Functional Role


? Deranged Cellular Environment
? Cell membrane Damage
? Tissue Necrosis
? Cell Death
Mitochondrial Electron Transport Chain

Defects

Due to Phospholipid Deficits



Fatty Liver

Due to Phospholipid Defects

This post was last modified on 05 April 2022