An Edited Version of an Already Existing Carbohydrate Presentation from SlideShare

1. Carbohydrate Chemistry
Structure and Isomerism

2. Structure of Monosaccharides
Fischer
projection
• The straight
chain
structural
formula
Haworth
projection
• Cyclic
formula or
ring structure
X-ray
diffraction
analysis
• Boat and
chair
conformation

3. Straight chain
Ring structure
Chair form

7. Isomerism
• The compounds possessing identical
molecular formula but different
structures are called isomers.
Various types of isomerism
1. Structural isomerism
2. Stereoisomerism

8. Structural Isomerism
• Same molecular formulae but differ from
each other by having different structures.

9. Stereoisomerism
• Same molecular formula and same
structure but they differ in configuration.
• That is, they differ in the arrangement of
their atoms in space.
• Presence of asymmetric carbon atoms
allow the formation of stereoisomerism

10. Stereoisomerism
• The important types of stereoisomerism
associated with glucose are
D and L enantiomerism
Optical isomerism
Epimerism
α and β anomerism

11. D and L Enantiomerism
“Handedness”
• Stereoisomers that are
nonsuperimposable mirror images of each
other.
• Handedness (D and L forms) is
determined by the configuration at the
high-numbered chiral carbon.

12. D and L Enantiomerism
“Handedness”

13. Optical Isomerism
• Optical activity is the capacity of a
substance to rotate the plane polarized
light passing through it.
Clockwise direction
• Dextrorotatory (d) or (+)
Counterclockwise direction
• Levorotatory (l)or (-)

14. Optical Isomerism

15. Epimerism
• Epimerism is the stereoisomerism if two
monosaccharides differ from each other in
their configuration around a single specific
carbon (other than anomeric) atom.

16. Epimerism

17. Anomerism
• These are isomers obtained from the
change of position of hydroxyl group
attached to the anomeric carbon e.g. 
and  glucose are 2 anomers.
• Also  and  fructose are 2 anomers.

18. Anomerism

19. • Mutarotation is defined as the change in
the specific optical rotation by the
interconversion of α and β forms of D
glucose to an equilibrium mixture
Mutarotation

20. Structure of Oligosaccharides
• Disaccharides
Disaccharides
Reducing
Maltose
Lactose
Isomaltose
Nonreducing
Sucrose

21. Disaccharides
• These are glycosides formed by the condensation
of 2 simple sugars.
• If the glycosidic linkage involves the carbonyl
groups of both sugars ( ) the resulting
disaccharide is
• On the other hand, if the glycosidic linkage involves
the carbonyl group of only one of the 2 sugars (as
in maltose and lactose) the resulting disaccharide is
reducing.

27. Polysaccharides
• These are formed by the condensation of n
molecules of monosaccharides with the removal
of n-1 molecules of water. Since condensation
involves the carbonyl groups of the sugars,
leaving only one free carbonyl group at the end
of a big molecule, polysaccharides are non-
reducing.
• They are of 2 types:
1. Homopolysaccharides (e.g. starch, glycogen,
cellulose).
2. Heteropolysaccharides (e.g. glycosaminoglycans,

30. - 1,4 linkage between
two glucose units
-1,6 linkage between
two glucose units

32. Aldehyde
group
H-C=O
Monosaccharides
Enantiomers
Nonsuperimposable
mirror images of
each other
Disaccharides
Sucrose = glucose + fructose
Lactose = galactose + glucose
Maltose = glucose + glucose
Oligosaccharides Polysaccharides
Homo-
Starch, glycogen,
cellulose
Hetero-
GAGs
Epimers
Differ in
configuration
around one
specific
carbon atom
Isomers
Same
chemical
formula
Ketoses
Ketone
group
C=O
Aldoses
Tri-
Tetra-
Penta-