This document discusses carbohydrate chemistry. It defines carbohydrates as organic molecules found in nature that are made up of carbon, hydrogen, and oxygen. Carbohydrates are classified based on their structure into monosaccharides, disaccharides, oligosaccharides, and polysaccharides. Monosaccharides include important hexoses like glucose and fructose. Carbohydrates exhibit properties like optical activity and stereoisomerism due to asymmetric carbon atoms. Key topics covered include glycosidic linkages, reducing sugars, ring structure forms (pyranose and furanose), and epimers. Physiologically important monosaccharides and derived sugars are also mentioned.
3. • Carbohydrates are aldehyde or
ketone compounds with multiple
hydroxyl groups.
• The basic molecular formula
(C.H2O)n where n = 3 or more.
• The term ―carbohydrate comes
from the observation that when you
heat sugars, you get carbon and
water (hence, hydrate of carbon).
5. Monosaccarides-1
• * Def : They are the simplest
carbohydrate unites which can not be
hydrolyzed to a simpler form
• * General formula: (CH2O)n n≥3
6. :* Nomenclature
• 1- According to active group in
the sugar:
– If monosaccharide contains
aldehyde group (CHO) → it's
called aldose.
– And if contain ketone group
(c=o) → it's called
ketose.
8. Three Carbon Four Carbon
By combining the two methods , we find that:-3
3c-Aldotriose -ketotriose
4c-Aldotetrose -ketotetrose
5c-Aldopentise -ketopentose
6c-Aldohexose -ketohexose
13. An aldehyde or ketone can react with an
alcohol in a 1:1 ratio to yield a hemiacetal or
hemiketal, respectively, creating a new chiral
center at the carbonyl carbon
Hemiacetals or Hemiketals
16. carbon, AsymmetricAnomeric
carbon):chiralcarbon atom (
• It is that carbon atom attached
to four different groups or
atoms.
• Formation of a ring results in the
creation of an anomeric carbon
at carbon 1 of an aldose or at
carbon 2 of a ketose.
17. Reducing sugars
• If the oxygen on the anomeric
carbon (the carbonyl group) of a
sugar is not attached to any
other structure, that sugar is a
reducing sugar.
• Only the state of the oxygen on
the anomeric carbon determines
if the sugar is reducing or
nonreducing—the other hydroxyl
groups on the molecule are not
involved
18. Reducing sugars
• A reducing sugar can
react with chemical
reagents (for
example, Benedict's
solution) and reduce
the reactive
component, with the
anomeric carbon
becoming oxidized.
20. Optical activity-1
• Def. It is the ability of the compound to rotate
plane polarized light to the right or to the left.
• If the compound rotates plane polarized light
to the right, it is called dextrorotatory, d or
(+).
• If it rotates plane polarized light to the left, it
is called levorotatory, l or (-).
21. • The direction of rotation is independent
of the stereochemistry
• of the sugar, so it may be designated
D(−), D(+), L(−), or L(+).
• For example, the naturally occurring
form of fructose is the D(−) isomer.
22. •• dextrorotatorydextrorotatory sugar (d or +):sugar (d or +):
glucose,glucose, galactosegalactose and starchand starch
•• levorotatorylevorotatory sugar (l orsugar (l or --):): fructosefructose
and invert sugarand invert sugar..
23. 2‐ Stereoisomerism
Compound that have the same structural formula but differ in
spatial configuration are known as stereoisomers and the
phenomenon is called stereoisomerism.
The number of possible isomers of a compound depends on the
number of asymmetric carbon atoms (n) and is equal to 2n.
Glucose, with four asymmetric carbon atoms, has 16 isomers.
24. • The more important types of isomers
include
– D and L isomers,
– pyranose and furanose ring structures,
– alpha and beta anomers,
– epimers and
– aldose-ketose isomers.
25. IsomersIsomers
Are compounds which have the same molecularAre compounds which have the same molecular
weight, same percentage composition, and differweight, same percentage composition, and differ
in their physical and chemical properties.in their physical and chemical properties.
-- StereoisomersStereoisomers: are compounds that have the: are compounds that have the
same structural formula but differ in spatialsame structural formula but differ in spatial
configuration (arrangement of atoms and groupsconfiguration (arrangement of atoms and groups
of atoms in space around the asymmetricof atoms in space around the asymmetric
carbon(scarbon(s) i.e. different configuration).) i.e. different configuration).
26. 1. D and L isomers
):enantiomers(
• A special type of
isomerism is found in
the pairs of structures
that are mirror image of
each other.
• These mirror images
are called enantiomers
and the two members of
the pair are designated
as a D and an L-sugar.
27. • A monosaccharide is
designated D if the
hydroxyl group on the
highest numbered
asymmetric carbon=
prelast carbon is drawn to
the right as in D-
glyceraldehyde and L if the
hydroxyl group on the
highest numbered
asymmetric carbon is
drawn to the left as in L-
glyceraldehyde.
32. • The cyclic α and β anomers of a sugar in
solution are in equilibrium with each other,
and can be spontaneously interconverted
(a process called mutarotation)
41. 3.Sugar acids
1.1. Produced by oxidation ofProduced by oxidation of
carbonyl carbon to carboxyliccarbonyl carbon to carboxylic
group.group.
2.2. Or by oxidation of last hydroxylOr by oxidation of last hydroxyl
carbon to carboxylic group.carbon to carboxylic group.
3.3. Or by oxidation of both.Or by oxidation of both.
45. Glycoside Formation
• The hemiacetal and hemiketal forms of
monosaccharides can react with alcohols
to form acetal and ketal structures called
glycosides. The new carbon-oxygen bond
is called the glycosidic linkage.
47. OH of other-2
compound :
• A- May be carbohydrate (
Monosaccharides can be linked to
each other by O- glycosidic bonds to
form disaccharides, oligosaccharides
and polysaccharides).
• (monosaccharide+
monosaccharide)=hemiacetal+hemia
cetal=acetal.
• b- May be non carbohydrate e.g
glycolipid, glycoprotein.
• The non carbohydrate component of
a glycoside is called aglycone.
48. O- and N-glycosides
• If the group on the non-
carbohydrate molecule
to which the sugar is
attached is an -OH
group, the structure is an
O-glycoside
• All sugar-sugar
glycosidic bonds are O-
type linkages
49. O- and N-glycosides
• If the group is an -NH2 ,
the structure is an N-
glycoside
– purines and pyrimidines
(found in nucleic acids),
– aromatic rings (such as
those found in steroids and
bilirubin),
– proteins (found in
glycoproteins and
glycosaminoglycans),
50. Naming glycosidic bonds
• Glycosidic bonds
between sugars are
named according to
– numbers of the
connected carbons (1-4,
1-6), and
– position of the
anomeric hydroxyl
group of the sugar
involved in the bond.
51. Naming glycosidic bonds
• this anomeric hydroxyl
group is in the α
configuration, the
linkage is an α-bond.
• If it is in the β
configuration, the
linkage is a β-bond.
52. Naming glycosidic bonds
• Lactose, for example, is
synthesized by forming a
glycosidic bond between carbon
1 of β-galactose and carbon 4 of
glucose.
– The linkage is, therefore:
β(1 →4) glycosidic bond.
• Because the anomeric end of the
glucose residue is not involved in
the glycosidic linkage it (and,
therefore, lactose) remains a
reducing sugar.
53.
54. Naming of O‐ glycosidic bond() carbohydrate and carbohydrate
‐ Glycosidic bonds between sugars are named according to:
1‐ The numbers of the connected carbons
2‐ The position of the anomeric hydroxyl group of the sugar.
If the anomeric hydroxyl group is in α configuration the link is α‐
bond and if it’s in β, the link is β‐ bond. Examples
In lactose β 1 of galactose bind to C4 of glucose by β 1 → 4
galactosidic bond.
55. Examples of glycosides:
1‐ Disaccharides as maltose, lactose and sucrose
2‐ Polysaccharides.
3‐ Glycolipids.
4‐Glycoproteins.(may be O‐ or N‐ glycosidic link)
5‐Nucleotides as ATP, GTP, UTP where aglycon is purine or
pyrimidine bases (N‐ glycosides)
The glycosides that are important in medicine
1. cardiac glycosides all contain steroids as the aglycone.
2. Other glycosides include antibiotics such as streptomycin.
56. Disaccharides
‐ Disaccharide consists of two sugars joined by an O‐ glycosidic bond.
‐ The most abundant disaccharides are sucrose, lactose and maltose.
‐ Other disaccharides include isomaltose, cellobiose and trehalose.
‐The disaccharides can be classified into homo disaccharides and
hetero disaccharides.
‐A) Homo disaccharides: are formed of the same monosaccharide units
and include maltose, isomaltose, cellobiose and trehalose.
‐(B) Hetero disaccharides: are formed of different monosaccharide
units and include: sucrose, lactose.
57. Lactose:Lactose:
It is formed of -galactose and -glucose linked by
-1,4-glucosidic linkage
Contain free anomeric carbon so reducing sugar
It may appear in urine in late pregnancy and during
lactation.
O
OH
H H
H
OHH
OH
CH2OH
H
O
H OH ..... H
H ..... OH
H
OHH
OH
CH2OH
H
and Lactose
-Galactose Glucose
1 4O
58. SucroseSucrose
• α D-glucopyranose and
β D fructofuranose by α
1- 2 glycosidic bond
• No free aldehyde or
keton gp so non
reducing sugar
• hydrolysed to glucose
and fructose by sucrase
(invertase) enzyme.
• * Sucrose is
dextrorotatory +66.5.
O
H
OH
H
H
OHH
OH
CH2OH
H
1
Sucrose
-Glucose
-Fructose
CH2OH
O
H
CH2OH
OH H
H OH
O
2
59. Maltose (malt sugar):Maltose (malt sugar):
It consists of 2It consists of 2 --glucose units linked byglucose units linked by
--1,41,4--glucosidic linkage,glucosidic linkage,
Contain free anomeric carbon so reducing sugar.
O
H
OH
H
H
OHH
OH
CH 2OH
H
O
H OH ..... H
H ..... OH
H
OHH
OH
CH 2OH
H
O
and Maltose
-Glucose Glucose
1 4
60. B.B. TrehaloseTrehalose::
It is formed of 2 -glucose units linked by -1,1-
glucosidic linkage. Not Contain free anomeric
carbon so non reducing sugar
Present in a highly toxic lipid extracted from
Mycobacterium tuberculosis.
O
H
OH
H
H
OHH
OH
CH 2O H
H
O
H H
OH
HO H2C
H
OHH
OH H
O
11
Trehalose
-Glucose -Glucose
61. Disaccharides Components Reduction
1- sucrose =
cane sugar
= beet sugar =
table sugar
α D-
glucopyranose
and β D
fructofuranose.
by α 1- 2
glycosidic bond
No free
aldehyde or
keton gp so
non reducing
sugar
hydrolysed to
glucose and
fructose by sucrase
(invertase) enzyme.
* Sucrose is
dextrorotatory
+66.5.
2- Lactose (milk
sugar)
β D galactose
and α D glucose.
by β 1-4
glycosidic bond
Contain free
anomeric
carbon so
reducing
sugar
* It may appear in
urine in late
pregnancy and
during lactation.
62. Disaccharides *Components Bond Reduction
1- Maltose 2αD-glucose α 1-4 glycosidic Contain free
anomeric
carbon so
reducing sugar.
4- Trehalose 2αD-glucose α 1-1 glycosidic Not Contain
free anomeric
carbon so non
reducing sugar
65. 1. Starch
‐ is a homopolymer of glucose forming an α‐ glucosidic chain, called a
glucosan or glucan.
‐It is the most abundant dietary carbohydrate in cereals, potatoes,
legumes, and other vegetables.
‐The two main constituents are amylose (15–20%), which has a
nonbranching helical structure) and amylopectin
(80–85%), which consists of branched chains composed of 24–30
glucose residues united by 1 → 4linkages in the chains and by 1 → 6
linkages at the branch points.
:Dextrins2.
Are intermediates in the hydrolysis of starch.
66.
67. •• AmyloseAmylose::.. Straight chain compoundStraight chain compound
present in the form glucose unitspresent in the form glucose units
linked bylinked by --1,41,4--glucosidic bond of aglucosidic bond of a
helix formed of a large number ofhelix formed of a large number of --
glucose.glucose.
O
H H
H
OHH
OH
CH 2 OH
H
O
H H
OHH
OH
CH 2 OH
H
O
Am ylose
14
n
O
O
1 4
It forms the inner part of starch granules
72. Glycosaminoglycans (GAGs)
(Mucopolysaccharides)
‐ Glycosaminoglycans are long linear (unbranched)
heteropolysaccharide chains generally composed of a repeating
disaccharide unit (acidic sugar‐amino sugar)n.
‐The amino sugar is either D‐glucosamine or D‐galactosamine in
which the amino group is usually acetylated, and sometimes
sulphated.
There are 6 types:
1. heparin. 2. heparan sulphate. 3. dermatan sulphate
4. keratan s 5. Chondroitin s 6. hyaluronic acid
75. • Glycoproteins have many functions:
• 1- Soluble as enzymes, hormones and
antibodies.
• 2- In lysosomes
• 3- attached to the cell membrane (The
membrane bound glycoproteins) participate
in:
– a- cell surface recognition (by other cells,
hormones, viruses)
– b- Cell surface antigenicity (as blood gp
antigens)
76. Proteoglycans Glycoprotein
Carbohydrate components
Glycosaminoglycans
- Repeating disaccharide unit
- Linear (unbranched)
- long
- Contain uronic acids (glucuronic
and iduronic
- N- acetyl hexosamine
- Contain hexoses as galactose (in
keratin sulphate)
- contain sulphate
- No pentoses
- No deoxy sugar
Oligosaccharides
- No repeating units
- Branched
- short
- contain sialic acid derivatives
(NANA)
- N- acetyl hexasamine
- Contain hexoses as galactose
and mannose
- No sulphate
- Contain pentose
-Contain deoxy sugar as L-fucose
77. 2- Tissue distribution and
functions
Structural
- Cartilage
- Bone
- Tendons
- Cell membrane
- Cornea
Functional and structural
- mucines
- Blood groups antigens
- some hormones
- enzymes
- Immunoglobulins and
receptors