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