Carbohydrates.pdf.monosaccharyde,polysaccharide

Carbohydrate

1. CARBOHYDRATES
Mst Rubaiat Nazneen Akhand
Associate Professor
Department of Biochemistry and Chemistry
Faculty of Biotechnology and Genetic Engineering
Sylhet Agricultural University
Sylhet-3100, Bangladesh

2. What is Carbohydrate?
■Carbohydrates are the polyhydroxyaldehydes or polyhydroxyketones that contain
Carbon, Hydrogen and Oxygen, the ratio between Hydrogen and Oxygen is 2:1 and
their derivatives.
■Emperical Formula: C
m
(H
2
O)
n
■Exceptions:
–Acetic Acid (C
2
H
4
O
2
), Lactice Acid (C
3
H
6
O
3
): Formula is C
m
(H
2
O)
n
, Non-Carbohydrate
–Deoxyribose (C
5
H
10
O
4
), Rhamnohexose (C
6
H
12
O
5
): Carbohydrate, Formula not-satisfied.
■Functions:
–Most abundant dietary source of energy (4 cal/g) for all organisms
–Precursors for many organic compounds; e.g, fats, amino acids
–Participate in the structure of cell membrane and cell functions like cell growth, adhesion
and fertilization; e.g, glycoproteins, glycolipids etc
–Structural components of many organisms; e.g, exoskeleton of some insects
–Serve as the storage of energy (e.g, glycogen) to meet the immediate energy demands of
the body

3. Classification
Carbohydrates
Monosaccharides
Based on C-
number
Triose
Tetrose
Pentose
Hexose
Heptose
Based on
Functional
group
Aldose
Ketose
Disaccharides
Reducing
Non-Reducing
OligosaccharidesPolysaccharides
Based on Structure
Homopolysaccharides
Heteropolysaccharides
Based on Functions
Structural
Functional

4. Carbohydrates
Monosaccharides
Disaccharides Oligosaccharides Polysaccharides
■Simplest group of Carbohydrates
■Often regarded as simple sugar
■Contains single polyhydroxyaldehyde or polyhydroxyketone unit
■Cannot be hydrolyzed
■General Formula: C
n
(H
2
O)
n
■Example: Glucose, Fructose etc

5. Carbohydrates
Monosaccharides
Disaccharides OligosaccharidesPolysaccharides
■Based on Carbon number
–Triose: Contains 3 Carbon molecules
■Glyceraldehyde: combines with phosphate; intermediate in glycolysis
■Dihydroxyacetone: combines with phosphate; intermediate in glycolysis
–Tetrose : Contains 4 Carbon molecules
■D-erythrose: Widely found, as phosphate participate in carbohydrate metabolism
–Pentose : Contains 5 Carbon molecules
■D-ribose: Contribute to RNA molecule formation
■D-Deoxyribose: DNA molecule formation
■D-Ribulose: Intermediate in HMP (Hexose monophosphate) shunt
–Hexose : Contains 6 Carbon molecules
■D-Glucose: Constituent of di,oligo,polysaccharides. Ready source of energy
■D-Fructose: Fruit sugar, Honey sugar
■D-Galactose: Constituent of lactose.
■D-Mannose: Structure formation of polysaccharides
–Heptose : Contains 7 Carbon molecules
■D-Seduheptulose: Intermediate in HMP shunt (PPP: Pentose phosphate pathway)

6. Carbohydrates
Monosaccharides
Disaccharides OligosaccharidesPolysaccharides
■Based on Functional Groups
–Aldehyde
■Contains (-CHO) aldehyde as functional group
■Glyceraldehyde, D-erythrose, D-ribose, D-Glucose
–Ketone
■Contains (-CH=O) ketone as functional groups
■Dyhydroxyacetone, D-erythrulose, D-ribulose, D-Fructose

7. Fischer Projection and Howarth’s Formula
Fischer Projection Formula Howarth’s Formula

8. ■Six-membered ring compounds are called pyranoses, as they
resemble six-membered ring compound pyran
–Glucopyranose, galactopyranose etc.
■Six-membered ring compounds containing a hemiketal
linkage are called furanoses.
–Fructofuranose
Pyranose and Furanose

9. ■A hemiacetal or a hemiketal is a compound that results from the addition of an  
alcohol to an aldehyde or a ketone, respectively. 
■Two molecules of an alcohol can add to a carbonyl carbon to form hemiacetal or
hemiketal.
■The Greek word hèmi, meaning half(semi), refers to the fact that a single alcohol
has been added to the carbonyl group, in contrast to acetals or ketals, which are 
formed when a second alkoxy group has been added to the structure.
Hemiacetal/Hemiketal Carbon

10. ■Reaction between the
aldehyde group at C1 and
the OH group at C5 forms
a hemiacetal linkage
■This produces either α-D-
glucose or β- D-glucose
Cyclic D-glucose
formation

11. ■The penultimate (second to last carbon) carbon is the last chiral carbon of the 
chain.
■The alcohol group attached to this carbon is that which attacks the carbonyl 
during cyclization of a sugar.
Penultimate Carbon

12. Monosaccharides exhibit Isomerism
■All the monosaccharides except dihydroxyacetone contain one
or more chiral carbon
■They are optically active and show isomerism
■Isomers are the molecules with identical molecular formula but
different structural configurations.
■Isomers do not necessarily share similar chemical or physical
properties.

13. Isomers: Classification
Isomers
Structural isomer
Chain
Positional
Functional
Metamerism
Tautomerism
Ring-chain
Stereoisomers
Geometrical Optical
EnantiomersDiastereomers
Epimers
Anomers

14. Isomers: Mainly two types
■Structural isomers: have identical molecular
formulas but differing in the order in which
the individual atoms are connected.
–E.g., C
3
H
6
O
■Stereoisomers: have same molecular
formula and the same structural formula but
differ in the spatial arrangement of the
atoms in the molecule.
–They are nonsuperimposable;
–can not align all atoms at the same time
–They are mirror image
–E.g., D-glucose and L-glucose

15. Isomers: Structural: Chain
Structural
isomer
Chain
Positional
Functional
Metamerism
Tautomerism
Ring-chain
•It is also known as Skeletal isomerism.
•The components of these isomers display
differently branched structures.
•Commonly, chain isomers differ in the
branching of carbon

16. Isomers: Structural: Positional
Structural
isomer
Chain
Positional
Functional
Metamerism
Tautomerism
Ring-chain
•The positions of the functional groups or
substituent atoms are different in
position isomers.
•Typically, this isomerism involves the
attachment of the functional groups to
different carbon atoms in the carbon
chain.

17. Isomers: Structural: Functional
Structural
isomer
Chain
Positional
Functional
Metamerism
Tautomerism
Ring-chain
•It is also known as functional group
isomerism.
•Same molecular formula, differ in
functional group.

18. Isomers: Structural: Metamerism
Structural
isomer
Chain
Positional
Functional
Metamerism
Tautomerism
Ring-chain
•This type of isomerism arises due to the
presence of different alkyl chains on each
side of the functional group.
•It is a rare type of isomerism and is
generally limited to molecules that contain
a divalent atom (such as sulfer or oxygen),
surrounded by alkyl groups.

19. Isomers: Structural: Tautomerism
Structural
isomer
Chain
Positional
Functional
Metamerism
Tautomerism
Ring-chain
•A tautomer of a compound refers to the
isomer of the compound which only differs
in the position of protons and electrons.
•Typically, the tautomers of a compound
exist together in equilibrium and easily
interchange.
•It occurs via an intramolecular proton
transfer.
•An important example of this phenomenon
is Keto-enol tautomerism.

20. Isomers: Structural: Ring-Chain
Structural
isomer
Chain
Positional
Functional
Metamerism
Tautomerism
Ring-chain
•In ring-chain isomerism, one of the isomers
has an open-chain structure whereas the
other has a ring structure.
•They generally contain a different number
of pi bonds.

21. Isomers: Stereoisomer: Geometrical
Stereoisomers
Geometrical Optical
Enantiomers Diastereomers
Epimers
Anomers
•It is popularly known as cis-trans isomerism.
•These isomers have different spatial
arrangements of atoms in three-dimensional
space.

22. Isomers: Stereoisomer: Optical
Stereoisomers
Geometrical Optical
Enantiomers Diastereomers
Epimers
Anomers
•Compounds that exhibit optical isomerism
feature similar bonds
•Different spatial arrangements of atoms
•Forming non-superimposable mirror
images.

23. Isomers: Stereoisomer: Enantiomers
Stereoisomers
Geometrical Optical
Enantiomers Diastereomers
Epimers
Anomers
•Enantiomers are chiral molecules that are 
mirror images of one another.
•Dextrarotatory (D) and Levorotatory (L) type
•In L-form, -OH group at the penultimate
carbon (the C before the last C) is on the left
side.
•In D-form, -OH group at the penultimate
carbon is on the right side.
•Majority of the sugars in higher animals are of
D-type.

24. Isomers: Stereoisomer: Epimer
Stereoisomers
Geometrical Optical
Enantiomers Diastereomers
Epimers
Anomers
•Diastereomers are not mirror images to each
other
•Epimers: If two monosaccharides differ from
each other in their configuration around a
single specific carbon (other than anomeric)
atom.

25. Isomers: Stereoisomer: Anomers
Stereoisomers
Geometrical Optical
Enantiomers Diastereomers
Epimers
Anomers
•Anomers are not mirror images to each other
•An anomer is an epimer at the hemiacetal/ 
hemiketal carbon in a cyclic saccharide, an 
atom called the anomeric carbon.
•α-anomer: OH group on the opposite of 
terminal carbon
•β- anomers: OH group on the same side of 
terminal carbon

26. Mutarotation
■Change in the special optical rotations, representing the interconversion of α, β- 
anomers to an equilibrium mixture.
+112.2° +18.7°+52.7°

27. Racemic Mixture
■Equimolar mixture of D and L-enantiomer
■They cancel the optical activity of each other

28. Tautomerization of Monosaccharides
■Tautomerization or
Enolization
–The process of shifting
a hydrogen atom from
one carbon atom to
another to produce
enediols is known as
tautomerization.
C
OH
Enediols

29. Reducing properties of Monosaccharides
■Reducing property is the presence of free aldehyde or keto group of
anomeric carbon
■To identify reducing sugar following tests are performed:
–Benedict’s test
–Fehling’s test
–Barfoed’s test
■Enediol forms or sugars reduce cupric ions of copper sulfate to to
cuprous ions, which form a yellow ppt of cuprous hydroxide or a red ppt
of cuprous oxide

30. Oxidation of Monosaccharides
■Oxidation of aldehyde group
–Formation of gluconic acid
–CHOᾆ COOH
■Oxidation of Terminal alcohol
group
–Production of glucuronic acid
–CH
2
OHᾆ COOH
■Oxidation of both aldehyde and
alcohol group
–Production of glucaric acid

31. Reduction of Monosaccharides
■Treatment with reducing agent e.g., sodium amalgum
H-C=O ᾆ H-C-OH
■Reduction results in corresponding alcohols
–D-glucose ᾆ D-Sorbitol
–D-galactose ᾆ D-Dulcitol
–D-Mannose ᾆ D-Mannitol
–D-Fructose ᾆ D-Mannitol + D-Sorbitol
–D-Ribose ᾆ D-Ribitol
2H
H
|
|
R
|
R

32. Other Reactions of Monosaccharides
■Dehydration
–Treatment with H
2
SO
4
results in elimination of 3 H
2
O
–Produces hydroxymethyl furfural (Hexose) or furfural (pentose)
■Osazone formation
–Phenylhydrazine in acetic acid when boiled with reducing sugar,
forms osazone
■Ester formation
–In enzymatic or non-enzymatic reactions alcohol groups may be
esterified

33. Derivatives of Monosaccharides
■Sugar acid
–Formed by the oxidation
–E.g., gluconic acid, glucuronic acid
■Sugar alcohol (polyols)
–Formed by reduction of aldose or ketose
–E.g., sorbitol, mannitol
■Amino sugar
–When one or more –OH groups are replaced by –NH3 group
–E.g., D-glucosamine, D-galactosamine
■Deoxysugars
–They contain one oxygen less than present in the parent molecule
–Present in DNA
■L-ascorbic acids
–Structure of this water soluble vitamin closely resembles to
monosaccharide.

34. ■Produces two molecules of monosaccharides on hydrolysis
■Monosaccharide units held together by glycosidic bond
■Monosaccharide units are either similar or dissimilar
■Crystalline, water-soluble, sweet to taste
■Reducing
–Contains Free aldehyde or keto groups
–Maltose: Malt sugar; two glucose units
–Lactose: Milk sugar; Glucose and Galactose
■Non-Reducing
–Doesnot contain Free aldehyde or keto groups
–Sucrose: Table sugar; Constituent of cane sugar, beet sugar
–Trehalose: Source of energy in some bacteria, fungi, plants and invertebrate animals
Carbohydrates
Monosaccharides
Disaccharides
OligosaccharidesPolysaccharides

35. ■It is a covalent bond that joins a carbohydrate (sugar) molecule to another group, which
may or may not be another carbohydrate.
■Formed between the hemiacetal or hemiketal group of a saccharide (or a molecule derived
from a saccharide) and the hydroxyl group of some compund such as an alcohol.
■Substance containing a glycosidic bond is a glycoside.
■Glycosidic bonds can be either S-, N-, C- or O-
Sucrose
Glycosidic linkage

36. Carbohydrates
Monosaccharides Disaccharides
Oligosaccharides
Polysaccharides
■Produces 3-8 molecules of monosaccharides on hydrolysis
■Monosaccharide units held together by glycosidic bond
■Normally present as glycans
■Oligosaccharides and their derivatices in foods
–Gentio-oligosaccharides (produced from pustulan)
–Gluco-oligosaccharides (produced from sucrose)
–Human milk oligosaccharides (HMO) (human breast milk)
–Isomalto-oligosaccharides or IOS (produced from starch)
–Lactosucrose (produced from lactose and sucrose)
–Maltotriose (produced from starch during digestion, found in liquid glucose, brown rice syrup)
–Mannan-oligosaccharides or MOS (artificially produced)
–Melibiose-derived oligosaccharides
–N-acetylchito-oligosaccharides (derived from chitosan)
–Pectic oligosaccharides (derived from pectin)
–Xylo-oligosaccharides (produced from corncob and birch wood)
Oligosaccharides are often added to commercial foods as sweeteners or fiber

37. Carbohydrates
Monosaccharides Disaccharides
Oligosaccharides
Polysaccharides
■Digestion, Fermentation, Absorption, Function, Side Effects
–Oligosaccharides, except maltotriose, are indigestible, which means humans lack enzymes to break
them down in the small intestine, so they reach the large intestine, where beneficial colonic bacteria
break them down (ferment) to absorbable nutrients, which provide some energy–about 2 Calories 
(kilocalories) per gram in average.
–Certain breakdown products of oligosaccharides may have beneficial effect on large intestinal
lining.
■Most oligosaccharides act as a soluble fiber, which may help prevent constipation. 
■Ingestion of large amount of oligosaccharides can result in abdominal bloating  
and excessive gas (flatulence).
■Oligosaccharides as Prebiotics
–Prebiotics are non-digestible nutrients that selectively promote the growth of normal intestinal 
bacteria that may have beneficial effects on the large intestinal lining.
–Oligosaccharides currently considered as prebiotics include fructo-oligosaccharides (FOS) or 
oligofructose and trans-galacto-oligosaccharides

38. Carbohydrates
Monosaccharides Disaccharides Oligosaccharides
Polysaccharides
■Contains more than 8 molecules of monosaccharides
■Polymers of monosaccharides
■Also termed as glycans
■High molecular weight (>20,000)
Chitin
Glucosamine
Glucose
Starch
Glucose

39. ■Based on Structure
–Homopolysaccharides contains single monosaccharide units
■Starch, glycogen, cellulose, chitin
■Some provide structural functionality e.g., cell wall formation in plant, and some
serve as storage form and used as fuels.
Polysaccharides: Classifications
–Heteropolysaccharides contains multiple
monosaccharide units
■Hyaluronic acid, Heparin etc
■Provides extracellular support for
organisms of all kingdoms. E.g.,
–Peptidoglycan layer of bacterial cell
–In animals they produces matrix in
extracellular space, that hold
individual cells together and provide
protection, shape and support to
cells, tissues and organs.

40. ■Based on Function
–Structural contributes to structure formation
■Cellulose, chitin
–Storage polysaccharides are stored within cell
■Starch in plants, glycogen in animals
Polysaccharides: Classifications

41. Homopolysaccharides: Starch
■Starch is the storage form of carbohydrate in plant
■These are stored mainly in tubers like potatoes and seeds
■Starch is heavily hydrated, they have many exposed hydroxyl groups available to
hydrogen bond with water.
■Contains two types of glucose polymers: amylose and amylopectin

42. Homopolysaccharides: Starch
■Amylose
–contains long, unbranced chains of
α-D-glucose
–connected by α(1ᾆ4) bond
■Amylopectin
–MW of upto 200 million
–Highly branched; Branch has α(1ᾆ6) bond
–Branch points occur in every 24 to 30 residues.

43. Homopolysaccharides: Glycogen
■Polymer of α(1ᾆ4) linked glucose subunits (upto 50,000), with α(1ᾆ6) linked branches.
■More extensively branched and more compact than starch.
■Branch in every 8 to 12 residues.
■The main storage polysaccharide of animal cells, mainly in liver (~7% of the wet weight)
■Also present in skeletal muscle.
■Each branch in glycogen ends with a non-reducing sugar unit.
■So glycogen molecule with n-branches has n+1 nonreducing ends but only one reducing
end.
■Break down of glycogen starts from nonreducing ends.

44. Glucose is not stored in its monomeric form
Glycogen
concentration in
hepatocytes is 0.01 µM 
(equivalent to a
glucose concentration
of 0.4 M)
This amount of glycogen is insoluble and
no effect on osmolarity of cytosol.
1 µM=1X10
-6
M
Osmolarity would be
eleveted significantly.
Osmotic entry of
water inside cell
If hepatocyte
cytosol contain
0.4 M glycose
Rupture of
cell
The free energy change for glucose
uptake into cells against this very high
concentration gradiant would be very
large.
External
concentration of
about 5 mM
(concentration in
the blood of the
mammal)

45. ■Bacterial and yeast
polysaccharides
■Polymer of α(1ᾆ6) linked D-
glucose.
■All have α(1ᾆ3) branches; some
have α(1ᾆ2) and α(1ᾆ4) branches
■Dental plaque formed by bacteria
on the surface of teeth is rich in
dextrans. This allows bacteria to
stick to teeth and to each other.
■Dextrans provide a source of
glucose for bacterial metabolism.
Homopolysaccharides: Dextrans

46. Homopolysaccharides: Cellulose
■Tough, fibrous, water insoluble
■Found in cell wall of plants, particularly in
stalks, stems, trunks and all the woody
portions of the plant body
■Linear, unbranched homopolysaccharide
■Contains 10,000 to 15,000 β- D-glucose unit.
■β(1ᾆ 4) glycosidic bonds
■Most vertebrate animals can’t use cellulose as 
fuel source.
■Cellulase enzyme that breaks β(1ᾆ 4) glycosidic
bonds is absent in vertebrate animals

47. Homopolysaccharides: Chitin
■Contains N-acetyl glucosamine residues in β(1ᾆ 4) glycosidic bond
■Forms extended fibers similar to those of cellulose and can’t be 
digested by vertebrates.
■Principal component of the hard exoskeletons of many arthropods
like insects, lobsters and crabs.
■2
nd
most abundant polysaccharide.
June beetle

48. Heteropolysaccharides: Glycosaminoglycan (GAG)
https://themedicalbiochemistrypage.org/glycosaminoglycans-and-proteoglycans/
■GAGs or Mucopolysaccharides are long linear polysaccharides
■Consist of repeating disaccharides (double sugar) units.
■Two monosaccharides are:
–either N-acetylglucosamine or N-acetylgalactosamine.
–Uronic acid (either D-glucuronic acid or L-iduronic acid)
■Some GAGs contain esterified sulfate groups
■GAGs are highly polar and attract water
■Used in the body as lubricant or shock absorber
■Found extensively in animals and bacteria but absent in plants
■Example:
–Chondroitin sulfate/dermatan sulfate
–Heparin/ Heparan sulfate
–Keratan sulfate
–Hyaluronic acid

49. GAG: Hyaluronan
■Hualuronan (Hyaluronic acid) contains alternating residues of D-Glucuronic
acid and N-acetylglucosamine
■Upto 50,000 repeats of the basic disaccharide units
■MW is several million KD
■Forms clear, highly viscous noncompressible solutions

50. GAG: Hyaluronan
■Serves as lubricants in the synovial fluid of joints
■Present in vitreous humor of the vertebrate eyes
■It is a component of extracellular matrix
(ECM) of cartilage and tendons
■Contributes tensile strength and elasticity
■Hyaluronidase enzyme from pathogenic
bacteria can break down hyalurnon
■In some animal species, Hyaluronidase in
sperm hydrolyzes the outer GAG coat
around an ovum, allowing sperm
penetration.

51. ■These are generally much short polymers
■Contains 20-60 disaccharides units
■Composed of D-glucosamine and N-acetyl
galactosamine 4-sulfate
■Contains β(1ᾆ 3) and β(1ᾆ 4) glycosidic
bonds
■Covalently linked to specific proteins
(proteoglycans)
■Contributes to the tensile strength of
cartilage, tendons, ligaments, heart
valves and the walls of aorta
■Dermatan sulfate contributes to the
pliability of skin, present in blood vessels
and heart valves. The glucuronate is
replaced by L-iduronate (C5-epimer of
glucuronate).
GAG: Chondroitin 4-sulfate

52. ■These are generally much short polymers
■Contains ~25 disaccharides units
■No uronic acid, sulfate content is variable
■Composed of D-glucosamine and N-acetyl
galactosamine 4-sulfate
■contains β(1ᾆ 4) and β(1ᾆ 3) glycosidic bonds
■Present in cornea, cartilage, bone and a
variety of horny structures formed from
dead cells: horn, hair, hoofs, nails and claws
GAG: Keratan 4-sulfate

53. ■Generally much short polymers of 15-90 disaccharides units
■Composed of 2-O-sulfated iduronic acid and 6-O-sulfated, N-sulfated 
glucosamine, -Highly sulfated
■contains α(1ᾆ 4) glycosidic bonds
■Produced by all animal cells
■Intracellular form of heparan sulfate produced primarily by mast cells
(leukocyte)
■Purified heparin is used as anti-coagulant
GAG: Heparan sulfate

54. Heteropolysaccharides:Peptidoglycan
■Bacterial cell walls are strengthened by
peptidoglycan layers
■Consist of repeating disaccharides N-acetyl
glucosamine (NAG) and N-acetyl muramic acid
(NAM)
■Glycosidic bond: NAG β(1ᾆ 4)
NAM
■Linear polymers lie side by side
in cell wall, cross linked by
short peptides.
■Envelopes the entire cell and
prevents cell swelling and lysis

55. Glycoconjugates
■Glycoconjugates is the general classification for carbohydrates covalently linked with 
other chemical species such as proteins, peptides, lipids and saccharides.

■Glycoconjugates are formed in processes termed glycosylation
■Glycoconjugates can be:
–Glycoproteins
–Proteoglycans
–Glycolipids
–Glycosphingolipids
■These are involved in:
–Cell-cell interactions
–Cell cell recognition
–Cell-matrix interactions
–Detoxification process

56. Glycoconjugates: Proteoglycans
■Macromolecules of the cell surface of ECM
■One or more sulphated GAG chains are joined covalently to a membrane
protein or a secreted protein
■GAG chain bind to EC proteins through electrostatic interactions
between the protein and the negatively charged sugar moieties on the
proteoglycan
■Major components of all ECM

57. Glycoconjugates: Glycoproteins
■These are protein molecules
■Oligosaccharide chains are attached to amino acid side-chains
■Carbohydrate is attached to the protein in a co-translational or post-
translational modification (Glycosylation process)
■They are integral membrane proteins
■Play cell-cell interactions
■Several types of glycosylation:
–N-glycosylation: Attached to nitrogen
–O-glycosylation: Attached to oxygen
–P-glycosylation: Attached to phosphorous
–C-glycosylation: Attached to carbon
–S-glycosylation: Attached to sulfer

58. Glycoconjugates: Role of Glycoproteins***
■Mucins secreted in the mucus of the respiratory and digestive tracts
■Molecules such as antibodies (immunoglobulins), which interact directly with antigens.
■Major histocompatibility complex (or MHC), are expressed on the surface of cells and interact
with T-cells as part of the adaptive immune response.
■H antigen of the ABO blood compatibility antigens.
■Gonadotropins hormones (luteinizing hormone a follicle-stimulating hormone)
■Integrin protein found on platelets that is required for normal platelet aggregation and 
adherence to the endothelium.
■Components of the Zona pellucida, which surrounds the oocyte, and is important for sperm-
egg interaction.
■Structural glycoproteins, which occur in Connective tissue. These help bind together the fibers, 
cells, and ground substance of  Connective tissue. They may also help components of the 
tissue bind to inorganic substances, such as calcium in bone.
■Glycoprotein-41 (gp41) and glycoprotein-120 (gp120) are HIV viral coat proteins.
■Soluble glycoproteins often show a high viscocity, for example, in egg white and blood plasma
***For DVM and BGE only

59. Glycoconjugates: Glycolipids
■Lipids with a carbohydrate
attached by a glycosidic bond
■Found on the surface of cell
membrane
■Maintain stability of cell
membrane
■Facilitate cellular recognition
■Important for immune
response

60. Glycoconjugates: Glycosphingolipids
■Subtype of glycolipids, contain amino alcohol sphingosine
■Plasma membrane components
■Hydrophilic head groups are oligosaccharides
■Neurons are rich in glycosphingolipids: Helps in
–Nerve conduction and
–Myelin formation
■Play role in Signal transduction in
cells
■Glycosphingolipids include:
–Cerebrosides
–Gangliosides
–Globosides
Sphingosine