Download MBBS Biochemistry PPT 80 Polysaccharides Lecture Notes

Download MBBS (Bachelor of Medicine, Bachelor of Surgery) 1st year (First Year) Biochemistry ppt lectures Topic 80 Polysaccharides Notes. - biochemistry notes pdf, biochemistry mbbs 1st year notes pdf, biochemistry mbbs notes pdf, biochemistry lecture notes, paramedical biochemistry notes, medical biochemistry pdf, biochemistry lecture notes 2022 ppt, biochemistry pdf.


Biomedically Important

Polysaccharides/Glycans

? Polysaccharides are complex class of

Carbohydrates,

? Chemically composed of more than ten,

same or different Monosaccharide units or

their derivatives

? Repeatedly linked by glycosidic linkages.
? General Formula of Polysaccharides

(C H O )n

6 10 5

? Iodine test is a characteristic test for

Polysaccharides
? Iodine test is based on Physical property

of adsorption.

? Iodine get adsorbed on complex structure

of Polysaccharides to give characteristic

color.

Glucosan

? Type of Homopolysaccharide
? Repeating unit,of Glucosan is Glucose
? Glucosan is a Polymer of Glucose.

Starch

Glycogen
Cellulose
Dextrin
Dextran
Fructosan

? Type of Homopolysaccharide
? Repeating unit in Fructosan is Fructose.
? Fructosan is a Polymer of Fructose.
? Inulin

Starch

? Plant Homopolysaccharide
? Starch is Glucosan
? Repeating Unit -

D Glucose (approx 7000)

? Components of Starch-
? Amylose and Amylopectin
Amylose

? Amylose is 15-20%
? Linear structure
? D Glucose linked by (1-4) glycosidic

bond.

CH OH

CH OH

CH OH

2

CH OH

2

2

2

H

O H H

O H H

O H H

O H

H

H

H

H

( OH H

O

OH H

OH H

OH H

O

O

O

O)

H OH

H OH

H OH

H OH

amylose( -1,4 links)

Amylopectin

? Amylopectin is 80-85 %

? Branched structure

? Branching point appears after every

25-30 Glucose units.

? It has (1-6) glycosidic bond at branching

point.

? (1-4) glycosidic bonds in linear structure.
? Starch is white ,odourless, tasteless powder .
? Starch is insoluble in cold water, but get

solubilized on heating and form gel /paste.

? Starch is a non reducing Carbohydrate.

Starch -Negative Benedicts Test.

? Starch on Iodine reaction gives blue color.
Source/Occurrence Of Starch
? Plants- Seeds, Tubers, Roots, Raw fruits.

? Dietary Sources of Starch.

? Grains- Rice ,Wheat, Jawar, Bajra

? Potatoes

? Beetroot.

? Sago (Tapioca)

? Vermicelli

? Suji.

? Raw Mangoes

Digestion of Starch

? In mouth- by salivary Amylase

? In intestine -by pancreatic Amylase

? Amylase cleaves, (1-4) glycosidic bonds of

Amylose and Amylopectin and releases Maltose

and Isomaltose.

? Maltose and Isomaltose is then digested by

Maltase and Isomaltase to release free Glucose

units.

? Thus Starch on digestion gives thousands of free

Glucose units which have high calorific value.
Glycogen

? Animal Homopolysaccharide
? Animal Starch
? Glycogen is chemically Glucosan.
? Repeating Unit ?

D Glucose (25-30 thousand Glucose

units)

? Glycogen is like Amylopectin structure ,but

it is highly branched

? Branching points appear after every 8-10

Glucose units, linked by (1-6) glycosidic

bond.

? Linear structure has Glucose linked with

(1-4) glycosidic bond.

? On Iodine reaction Glycogen gives deep

red color.
Glycogen

? Glycogen has more (1 6) branches.

? The highly branched structure permits

rapid glucose release from glycogen

stores, in muscle during exercise.

? Glycogen is present in animal-

? Liver (75 gm)

? Muscle (125 gm).
? After well fed condition, free and excess of

Glucose is condensed to Glycogen via

Glycogenesis.

? Rate of Glycogen synthesis ?

? Liver- 6-8 %,

? Muscle 1-2 %

? Glycogen is broken down to Glucose via

Glycogenolysis when body Glucose lowers

in fasting and starvation condition.

? Dietary Glycogen in GIT is digested by

- Amylase to Maltose and Isomaltose

and finally to thousands of Glucose Units.

Liver Glycogenolysis in Human body

regulates Blood Glucose levels in fasting

condition.

Muscle Glycogenolysis provides energy for

muscle activities in fasting condition.
Sr. No

Starch

Glycogen

Starch is Plant Homopolysaccharide. Glycogen is animal Homopolysaccharide

1.
2. Starch is composed of Amylose Glycogen is highly branched structure

(Linear)&Amylopectin (Branched) with branching points appearing after

every 8-10 Glucose residues.

3. Starch is composed of 4000-7000 Glycogen is composed of 6000-30,000

Glucose units.

Glucose units.

4. Starch is a storage form of Glucose Glycogen is storage form of Glucose and

and reserve food material in plants. reserve form of energy in animals and

human beings.

5. Starch is stored in roots, tubers, Glycogen is stored in Liver and Muscles

seeds, raw fruits of plants.

of animal and human body.

6. Starch serves as predominant dietary Glycogen is dietary form of

Carbohydrate form in Veg and

Carbohydrate only in Non-Veg eaters.

Nonveg eaters.

7. Starch with Iodine test gives deep Glycogen with Iodine test gives deep red

Blue color.

color.

Cellulose

? Non digestible carbohydrate

? Cel ulose serve as dietary Fiber.

? Cellulose is a Glucosan

? Repeating Unit - D Glucose.

(approx 2,500- 14,000 ).

? Cel ulose is a linear ,unbranched structure where D Glucose

units repeatedly linked by (1-4 ) glycosidic bonds.
Source/Occurrence Of Cellulose

? Cellulose is an abundant carbohydrate of nature exclusively

present in Plants cell wall.

? Dietary rich sources of Cellulose

? Whole Grains (outer covering)

? Green leafy vegetables

? Cabbage, Cucumber

? Legumes, Nuts, Beans

? Dates

? Fruits and Vegetable salads.

? In plants Cellulose present in cel wal provides structural and

mechanical support.

Cellulose has Ef ec t on Fecal Mass

Formation

? Cellulose acts as a roughage.
? It holds water ,helps in forming soft and bulky feces.
? Increases intra luminal pressure.
? Reduces transit time of feces to remain in gut.
? Eliminates daily, metabolic wastes and toxins out of

the body, through feces.

? Defecation with greater ease and good frequency.
?Cellulose prevents constipation,

and reduces risk of :

colon cancer
diverticulosis of intestine
hemorrhoids

?Cellulose reduces the absorption of :

?Glucose

?Cholesterol

?Ameliorate the conditions of :

Diabetes mellitus

Atherosclerosis respectively.

Cellulose being non calorific and

possessing high satiety value helps

in managing obesity in humans.
? For maintenance of good health ingest

dietary fibers.

? RDA for dietary fiber to maintain good

health:

? Adults= 20-25 gm/day.

? Children's= 5-10 gm/day.

? Disadvantage of dietary Cellulose-
? It decreases absorption of minerals.

Dextrin

? Intermediate hydrolytic product of Starch

digestion

? Dextrin is a Glucosan
? Repeating Unit - D Glucose.

? Dextrin is less complex than starch

structure.

? Dextrin is broken Starch molecule.
Types Of Dextrin

? Amylodextrin -Violet to Iodine reaction

? Erythrodextrin- Red to Iodine reaction

? Achrodextrin -Colorless to Iodine reaction.

Source/Occurrence of Dextrin

? In human GIT Dextrin is obtained as an intermediate

hydrolytic product of Starch digestion by the action

of

-Amylase activity.

? Dextrin is Present in commercially prepared infant

foods.
Biomedical Importance Of Dextrin

? Dextrin has mucilage nature(sticky) hence

used as binding and adhesive agent.

? Dextrin is used as infant food.

Dex tran

? Dextran is a Bacterial Homopolysaccharide

? Dextran is a Glucosan

? Repeating Unit ? D Glucose.

? Highly branched, complex, network like structure

Glucose units linked by

(1-4) ,(1-6) and (1-3) glycosidic linkages.

?
Source/Occurrence Of Dextran

? Dextran is obtained from Sucrose solution

incubated with bacteria Leuconostoc

mesenteroides

? Dextran solution is high molecular weight,

viscous solution with osmotic pressure

equivalent to plasma Albumin.

? Dextran maintains blood volume and osmotic

pressure.
? Dextran solution is used as
? Plasma substitute/plasma volume

expander

? Dextran infusion manages a hemorrhagic

case and prevent from hypovoluemic

shock.

Sr.No

Dextrin

Dextran

1. Dextrin is plant

Dextran is bacterial

Homopolysaccharide

Homopolysaccharide.

2. Dextrin is an intermediary

Dextran is a Glucosan obtained

hydrolytic product of Starch from Sucrose solution incubated
digestion.

with Leuconostoc mesenteroides.

3. Structure of Dextrin contains Structure of Dextran contains

(1-4) & (1-6) glycosidic (1-3),
bonds.

(1-4) & (1-6) glycosidic bonds.

4. Dextrin solution is used in

Dextran solution is used as plasma

commercially prepared infant volume expander in relieving
feedings and mucilage for

hypovoluemic shock in cases of

pasting stamps.

hemorrhage.
Fructosan

? Homopolysaccharide with repeating units as

Fructose.

Inulin

?Diagnostic Carbohydrate

? Diagnoses Kidney Function- GFR of

Kidney.

?Natural y present in Plants

? Roots and tubers of Dandelions

? Onion and Garlic bulbs

? Chicory Plant.
Chemistry Of Inulin

? Inulin is a Fructosan

? Repeating Unit-

D Fructose units (33-35 units)

? Repeatedly linked by

(1-2) glycosidic bonds.

? Inulin is non digestible and non absorbable form in human GIT, hence have no

calorific value.

? Inulin solution infused intravenously during Inulin Clearance Test, checks

Glomerular Filtration Rate (GFR) of Kidney (120-125 ml/min).

Heteropolysaccharides

?Heteropolysaccharides are type of

Polysaccharides composed of more than 10

different

? Monosaccharide units or their derivatives

repeatedly linked by glycosidic bonds.
Animal Heteropolysaccharides

Mucopolysaccharides (MPS)

?Human Heteropolysaccharides

?Animal Heteropolysaccharides

?Glycosaminoglycans (GAGs)
? Mucopolysaccharides were first isolated

from Mucin hence the name

Mucopolysaccharides.

? Mucopolysaccharides chemically

composed of more than 10

Monosaccharide units and its derivatives

repeatedly linked by glycosidic bonds.

? Mucopolysaccharides are complex, long,

linear, unbranched, polyanionic.

The Glycosaminoglycans has

Disaccharide repeating unit linked

by glycosidic bonds of

Uronic Acid

Amino Sugar
? Uronic Acid ?

Glucuronic acid /Iduronic acid

(Iduronic acid is 5' Epimer of Glucuronic acid)

? Amino Sugar-

Glucosamine / Galactosamine

(Acetylated or Sulfated or Both)

Jeanloz suggested the term GAG's as these

biomolecules has amino sugars as repeating units.

Properties of GAG's

? GAG's are polyanionic and acidic due to

presence of

?COO- and SO4-- -

? GAG's are hydrophil ic and attract water and

helps in distributing water.

? MPS due to repulsion of charges:

? It appear slippery or sticky in appearance/mucus

like secretions

? It expand to occupy large space.
? MPS/GAG's imparts fol owing physical

properties-

?Turgor

?High Viscosity

?High Density

?High Buoyancy.

Body Mucopolysaccharides
? Acidic Non Sulfated MPS:

? Hyaluronic Acid

? Acidic Sulfated MPS:

? Heparin

? Heparan Sulfate

? Chondritin Sulfate

? Dermatan Sulfate

? Keratan Sulfate

? Neutral MPS:

? Blood Group Substances

Hyaluronic Acid

?Acidic Non sulfated MPS

? Repeating Disaccharide Unit

?Glucuronic acid

?NAcetylGlucosamine.

?Hyaluronic acid is present as

ground substance/cementing

substance in extra cellular

spaces of connective tissue.
? Hyaluronic acid in synovial fluid of joints

and vitreous humor of eye serve as lubricant
and shock absorbant.

? Hyaluronic acid around ovum gives

protection.

? Hyaluronic acid plays role in cell migration

during morphogenesis.

? Enzyme "Hyaluronidase " hydrolyses

Hyaluronic acid.

? Hylauronidase present in head of sperm ,

hydrolyzes the Hyaluronic acid present on

ovum which facilitates its penetration and

fertilization.

? Snake venom is rich in Hyaluronidase,

thus snake bite hydrolyzes and liquifies the

Hyaluronic acid present in extracellular

spaces of cells ( TOXIN )
Heparin

?Most Acidic Sulfated MPS.

Disaccharide Repeating Unit:

?Glucuronate sulfate ( minor )

?Iduronate sulfate (major)

?N-Glucosamine Sulfate.

?Heparin, a soluble

PDB 1RID

glycosaminoglycan

found in granules of

mast cells and is highly

sulfated.
?Heparin has an

extended helical

conformation.

heparin: (IDS-SGN)5
Occurrence and Functions Of Heparin

?Heparin present in blood vessels, Liver,

Lung, Spleen and Monocytes

?Natural anticoagulant.

?In blood, it inhibits clot formation by

interacting with the protein antithrombin.
? Heparin is an indirect Thrombin inhibitor

.

? Rapid inactivator of Thrombin.
? Thus antithrombotic agent.
? Prevents intravascular blood clotting.
? Heparin releases enzyme Lipoprotein

Lipase from endothelial lining and serve

as coenzyme for it. Clearing factor

Therapeutic Use of Heparin

? Heparin is infused to prevent and treat

thrombous located in vein/artery in MI cases.

? Deep Vein Thrombosis.
? Pulmonary Embolism
? Strokes
? Heparin(LMW Heparin) injections are given to

M.I patients

? To liquify blood ,prevent thrombosis and clear

blood with lipids.
Heparan Sulfate

? Acidic Sulfated Mucopolysaccharide

? Disaccharide repeating units
? Glucuronate Sulfate (major)/ Iduronate

Sulfate (minor)-N Acetyl Glucosamine
Occurrence and Functions Of

Heparan Sulfate

? Heparan Sulfate present on extracel ular cell

surfaces or plasma membranes and serves as

receptors

? Participate in cell growth, cell adhesion, and

cell -cell communication.

? Heparan sulfate in basement membrane of

kidney helps in determining charge

selectiveness of Glomerular filtration.

? Heparan sulfate are also components of aorta,

liver, fibroblasts, synaptic and vesicles.
Chondritin Sulfate

Acidic Sulfated Mucopolysaccharide

? Disaccharide Repeating Unit

? Glucuronate-

? N ?Acetyl Galactosamine ?Sulfated.

? Chondritin Sulfate A-4 sulfated.

? Chondritin sulfate C-6 sulfated.

Occurrence and Functions Of

Chondritin Sulfate

? Chondritin Sulfate is present in connective

tissues-bones, cartilage, tendons .

? It gives mechanical strength,

compressibility and support to connective

tissues.

? Chondritin sulfate present in cornea give

over all shape to eye.
Dermatan Sulfate

? Acidic Sulfated Mucopolysaccharide.

? Chondritin sulfate-B / -Heparin

? Disaccharide Repeating Unit

? L-Iduronate-

? N-AcetylGalactosamine-sulfated

? Dermatan sulfate especially present in skin, blood

vessels and heart valves gives mechanical strength and

structural support to these tissues.

? Dermatan sulfate plays structural role in sclera of eye.

Keratan Sulfate

? Acidic Sulfated Mucopolysaccharide

? Keratan Sulfate is a MPS without Uronic acid instead

contains Galactose.

? Disaccharide Repeating Unit

? Galactose-N-Acetyl Glucosamine ?sulfated

? Keratan sulfate present in cartilage, aorta walls, gives

structural supports and mechanical strength.

? Keratan sulfate present in cornea and lens of eye has role in

lens transparency and shape of eye.
Applied aspects of

Mucopolysaccharides/ GAGs

? On ageing or during pathogenesis the

biosynthesis of certain specific

Mucopolysaccharide /Glycosaminoglycan

is either increased or decreased leading

to disorders and manifestations.

? Tumors cells-

? Increased Hyaluronic acid (Increases cell

migration)

? Decreased Heparan Sulfate (Decreases

cell adhesion)

? This Increases Metastasis
? Rheumatic Arthritis-

? Rheumatic nodule shows increased

Hyaluronic acid deposition.

? Atherosclerotic plaque-

? Excess production of Dermatan Sulfate

? Decreased production of heparin

? Osteoarthritis-

? Imbalance biosynthesis of Hyaluronic acid,

Chondritin Sulfate and Keratan Sulfate

Glycoprotein Or Proteoglycans

? Proteoglycans are composed of as many as 200 GAG

chains covalently bonded to a core protein via Serine/

Threonine side chains.

? Molecular weight range: 105 ? 107 Daltons.

? GAG chains linked:

? Hyaluronic acid

? Chondroitin sulfate

? Heparan sulfate

? Dermatan sulfate

? Keratan sulfate

Examples of Proteoglycans

?

Aggrecan

(Hyaluronate-Core Protein non covalently linked In

Cartilage)

?

Biglycan

?

Beta Glycan

?

Decorin

?

Serglycin

?

Syndecan

?

Perlecan

?

Versican
Plant Heteropolysaccharides

Agar-Agar

? Agar is obtained from red algae.(Sea weed)
? Agar is formed of two main components, Agarose and

Agaropectin.

? Agarose is a neutral galactose polymer, free from sulfate.
? Agaropectin is formed of galactose and galacturonic acid

units partially esterified with sulfuric acid.
Uses of Agar

?Preparation of bacteriological

culture media.

?Emulsifier, thickener for ice

creams,puddings.

?Laxative-for treatment of ulcers

and chronic constipation.

Pectin

?Obtained from apple pomace and inner portion

of citrus rind.

?Form viscous solutions in water.

?Composed of Arabinose, Galactose and

Galactouronic acid.

?Average molecular weight 100,000- 250,000.
Uses Of Pectin

? Pectin is topically applied as a paste in cases of burns

and ulcers.

? It acts as a detoxifying agent by conjugation with

toxins.

? It is of great importance in treatment of diarrhea and

dysentery.

? It is used as a gel and emulsion stabilizer and in

manufacture of jellies and jams.

Diagnostic Value of Carbohydrate:

? Fructosan Inulin, is used to carry out:
? Inulin Clearance Test, which checks, Glomerular

Filtration Rate of kidney.
Therapeutic Value of Carbohydrates:

? Cardiac Glycosides Digoxin- used to

treat cardiac insufficiency.

? Glycosides Ovabain and Phlorizin- used

in treatment of Diabetes mellitus.

? Glycosides Streptomycin ,Erythromycin

used to treat bacterial infections.

? Mannitol- Serve as osmotic diuretic used in

treatment of Acute Renal Failure.

? Lactulose -Relives Hyperammonaemia in

patients of Hepato Encephalopathy.

? Dextran- Used as plasma substitute in

hemorrhagic cases to prevent hypovoluemic

shock.

? Hyaluronan- Used to treat osteoarthritis.

This post was last modified on 05 April 2022