Transcript File
Carbohydrates
Dr. Nasim
AP Biochem
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Monosaccharides
(Single sugar residue)
3 C:
4 C:
5 C:
6 C:
6 C:
Trioses
Tetroses
Pentoses
Hexoses
Hexoses
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Monosaccharides
(Single sugar residue)
(Aldose)
(ketose)
Glyceraldehydes
Erythrose
Ribose
Xylose
Glucose
DHA 3C
Erthrulose - 4 C
Ribulose - 5 C
Xylulose
5C
Fructose - 6 C
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Monosaccharides
Aldoses: Those Monosaccharides which
contain Aldehyde group. (H-C=O)
Ketose: Those Monosaccharides which
contain keto group. (C=O)
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Monosaccharides
Anomeric carbon: Aldoses & Ketose
may cyclize to produce an Anomeric
carbon.
Anomeric carbon contain reactive
hydroxyl group.
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Monosaccharides
If the Reactive hydroxyl group is free (Not
attached to any other molecule) then the
sugar is known as reducing sugars.
Reactive hydroxyl group may attached
covalently to another molecule.
N-Glycosidic linkage: If the Reactive
hydroxyl group is attached to–NH2
group.
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Monosaccharides
O-Glycosidic linkage: If the Reactive
hydroxyl group is attached to–OH group.
ISOMERS: If 2 compound have the same
chemical formula. E.g. Fructose &
glucose are isomers of each other.
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Monosaccharides
Epimers: If 2 compound have the same
chemical formula but the differ in
configuration around 1 specific C atom.
Galactose & glucose are C 4 Epimers of
each other.
Mannose & glucose are C 2 Epimers of
each other.
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Monosaccharides
Enantiomers: If 2 compound are mirror image
of each others.
E.g. L - Glucose & D – Glucose.
The configuration of asymmetric carbon atom
farthest from the aldehyde or keto group (with
reference to D or L glyceraldehydes)
determines whether a monosaccharide is of D
or L series.
In D form OH gp is on right side & vice versa in
left side.
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Disaccharides
(2 Monosaccharides units)
Sucrose = Glucose + Fructose
(α1-2 linkage)
Lactose = Glucose + Galactose
(β1-4 linkage)
Maltose = Glucose + Glucose
(α1-4 linkage)
Iso-malotose = Glucose + Glucose (α1-6)
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Oligosaccharides
(3-10 Monosaccharides)
E.g. Maltotriose: Compose of 3 Glucose
residues.
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Polysaccharides
(>10 Monosaccharides units)
Homo Polysaccharides
(contain same type of monosaccharides)
Glycogen which is also known as animal
starch.
Dextrin
Dextran
Cellulose
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Polysaccharides
Hetero Polysaccharides
(contain same type of monosaccharides
or different monosaccharides along with
prosthetic groups)
Muco Polysaccharides
Mucilages
Hemicellulose
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Polysaccharides
Hetero Polysaccharides
Muco Polysaccharides
Hyaluronic acid
Heparin
Chondroitin sulphate
Blood group Polysaccharides.
Serum mucoids
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Polysaccharides
Hetero Polysaccharides
Mucilages
Agar
Vegetable
Pectin
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Monosaccharides
Glyceraldehydes:
Reference sugar
All sugars are derived from it
D & L forms are refer to it
DHA
Produced from glucose in glycolysis &
also from glycerol which is produced in
break down of fats
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Monosaccharides
Erythrose & Erthrulose
Produced from glucose in HMP shunt
Can be converted to glucose
Ribose
Produced from glucose in HMP shunt
Ribose component of RNA
Deoxy-Ribose component of RNA
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Monosaccharides
Ribulose, Xylose & Xylulose
Produced from glucose in HMP shunt
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Monosaccharides
Glucose
Grape sugar
Dextrose
Dextro-rotation
Most common source sucrose which is
table sugar
Main source of energy for body &
specially brain.
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Monosaccharides
Glucose (Cont.)
FBS 60 – 100 mg/dl
RBS 100 – 160 mg/dl
On reduction glucose forms alcohol e.g.
Sorbitol
On oxidation sugar acids
Gluconic acid If oxidation of C1 of
glucose
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Monosaccharides
Glucose (Cont.)
Glucuronic acid If oxidation of C6 of
glucose
Glucaric acid If oxidation of C1& C6 of
glucose
Glucuronic acid is used for detoxification
of various toxic substances
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Monosaccharides
Galactose
Main source Lactose which is milk sugar
C 4 epimer of glucose
Mannose
Can be converted to glucose
On reduction forms Mannitol
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Monosaccharides
Fructose
Levulose.
Levo-rotation.
Sweetest among all sugars.
Most common source Sucrose (table sugar).
Pure honey = Fructose only.
Fructose Glucose.
Entry into cells is independent of Insulin.
Source of energy for sperms.
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Disaccharides
Maltose = Glucose + Glucose (α1-4)
Fruit sugar
Reducing sugar
Produced from starch by hydrolysis due
to salivary & pancreatic amylase.
Hydrolyzed by Maltase
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Disaccharides
Lactose = Glucose+ Galactose (β1-4)
Milk sugar
Reducing sugar
Hydrolyzed by Lactase
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Disaccharides
Sucrose = Glucose + Fructose (α1-2)
Cane sugar
Table sugar
Non-reducing sugar
Invert sugar
Hydrolyzed by Sucrase (Invertase)
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Polysaccharides
Homo Polysaccharides
Glycogen
Store from of Glucose
Present mostly in Liver & Muscles.
Animal starch
Branched structure (Tree like)
Less then 12 glucose residues
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Polysaccharides
Homo Polysaccharides
Glycogen (Cont.1)
Within a chain (α1-4) broken by
Phosphorylase enzyme.
At branch point (α1-6) broken by debranching enzyme.
Blood glucose levels are usually
maintained by Liver glycogen stores.
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Polysaccharides
Homo Polysaccharides
Starch
Most of dietary carbohydrates are in this
form.
2 types
Amylose (Straight chain)
Amylopectin (Branched structure) more
then 12 residues in each chain.
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Polysaccharides
Homo Polysaccharides
Starch (Cont.)
Hydrolyzed by salivary & Pancreatic
amylase into Maltose, Maltotriose &
dextrins.
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Polysaccharides
Homo Polysaccharides
Dextrins
Intermediate product of hydrolysis of
starch.
E.g. Amylodextrins, Erythrodextrins &
Achrodextrins.
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Polysaccharides
Homo Polysaccharides
Dextrans
Highly viscous.
Polysaccharides
Plasma expander.
Cellulose
Can’t be digested.
Increase bulk of stool.
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Polysaccharides
Hetero Polysaccharides
Muco Polysaccharides
Animal origin
Mucoprotein & Mucin (when in
combination with proteins)
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Polysaccharides
Hetero Polysaccharides
Muco Polysaccharides
Subtypes
Hyaluronic Acid
Chondroitin sulphate
Heparin
Blood group Polysaccharides
Serum mucoids
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Polysaccharides
Muco Polysaccharides
Hyaluronic Acid (Cementing agent)
Present in skin, synovial fluid, seminal
fluid & vitreous humor.
Functions
Prevents penetration of bacteria into skin
Lubrication of the joints
Helps in fertilization
Hydrolyzed by Hyaluronidase
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Polysaccharides
Muco Polysaccharides
Chondroitin sulphate
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Polysaccharides
Muco Polysaccharides
Heparin
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Polysaccharides
Muco Polysaccharides
Blood group Polysaccharides
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Polysaccharides
Muco Polysaccharides
Serum mucoids
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Polysaccharides
Mucilages
Plant origin
Agar
Non-digestible
Laxative
Culture media
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Polysaccharides
Vegetable gums
Used in pharmaceutical industry
Pectins
For making jellies
Hemicellulose
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Asymmetric carbon atom
Asymmetric carbon atom: The carbon atom to
which 4 different chemical groups are attached
& it can rotate plain polarized light to the right
or to the left.
E.g. Open chain formula of Glucose contains 4
Asymmetric carbon atoms. (C2, 3, 4 & 5).
E.g. Close chain formula of Glucose contains 5
Asymmetric carbon atoms. (C1, 2, 3, 4 & 5).
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Optical Isomers
Those sugars which rotates plain
polarized light to right are (d) sugars &
which to left are (l) sugars.
Racemic Mixture:
Such a solution which contains equal
amount of Levo & dextro-rotatory then
rotation of light will be equal but in
opposite direction.
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Ring Structure
Hemiacetal ring: if the ring is formed by
aldehyde gp.
Hemiketal ring: if the ring is formed by
keto gp.
Pyranose Ring: 6 sided ring. O2 bridge
b/w C1 & C5.
Furanose Ring: 5 sided ring. O2 bridge
b/w C1 & C4.
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Anomeric carbon
C of Aldehyde or keto gp forming
hemiacetal or Hemiketal rings.
C1 in Aldo-sugars. E.g. glucose
C2 in keto sugars. E.g. fructose
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Mutarotation
The direction of plain polarized light in a
freshly prepared glucose solution goes
on changing for some time before settling
to specific direction.
Reason: unfolding of ring structure to
striaght chain in order to maintain
equilibrium b/w α & β forms of sugars.
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Phenomenon of Inversion
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