corbohydrates chemistry structure of isomerism

• The compounds possessing identical
molecular formula but different structures are
called isomers.
Various types of isomerism
1. Structural isomerism
2. Stereoisomerism
Stereoisomerism
• Same molecular formula and same structure
but they differ in configuration.
• That is arrangement of their atoms in space.
• Presence of asymmetric carbon atoms allow
the formation of stereoisomerism

1. Carbohydrate chemistry II
Structure and Isomerism
Dr. Vijay Marakala, MD.
Assistant professor
BIOCHEMISTRY
SIMS & RC

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

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 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 isomerism
Optical isomerism
Epimerism
αand βanomerism

11. D and L isomerism

12. 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 (-)

13. Optical isomerism

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

15. Epimerism

16. 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.

17. Anomerism

18. •Mutarotaion is defined as the change in the
specific optical rotation by the interconversion
of αand βforms of D glucose to an
equilibrium mixture
Mutarotaion

19. Structure of oligosaccharides
•Disaccharides
Disaccharides
Reducing
Maltose
Lactose
Isomaltose
Nonreducing
Sucrose

20. 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.

26. POLYSACCHARIDES
•These are formed by the condensation of nmolecules of
monosaccharides with the removal of n-1molecules 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, glycoproteins)

29. -1,4 linkage between
two glucose units
-1,6 linkage between
two glucose units

31. Aldehyde
group
H-C=O
Monosaccharides
Enantiomers
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
Keto
group
C=O
Aldoses