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Carbohydrate Classification
1. N u mbers 2. Location of carbonyl group 3. N u mber of carbon atoms 4. C o n figuration 5. Reactivity
Common hexoses 1. A ldoses 2. K etoses
Stereochemistry 1. C h i rality 2. Enantiomers 3. D- & L-sugars 4. P hysical properties 5. F isher projections 6. Haworth formulae 7. S t e reo projections 8. Chair presentations
Conformation 1. I n t ramolecular cyclization 2. A n o mer 3. M utarotation 4. F uranose & pyranose
Some important monosaccharide
1. D - g lyceraldehyde 2. D - g lucose 3. D - f ructose 4. D-galactose 5. D - ribose
Disaccharide 1. G lycosidic bond 2. Disaccharide
Oligosaccharide Polysaccharide
Carbohydrate
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¶ Sugar Glucose + Sucrose
· Starch
¸ Cellulose
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Carbohydrate Compounds contain C, H, O with
general formula of Cm(H2O)n
All have C=O and -OH functional groups
Classified based on Size of base carbon chain Number of sugar unit Location of C=O group Stereochemistry
Types of Carbohydrates Classification based on the number of sugar units in the total chain
Monosachcarides Single sugar unit Disaccharides Two sugar units Trisachcarides Three sugar units Oligosaccharides up to 10/13/ sugar units Polysaccharides > 13 sugar units
Chaining relies on the glycosidic bonds
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Fischer Projections
• Used to represent carbohydrates (chiral carbons)
• Places the most oxidized group at the top (C1)
• Uses horizontal lines for bonds that come forward
• Uses vertical lines for bonds that go back
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D and L Notations
• By convention, the letter L is assigned to the structure with the —OH on the left
• The letter D is assigned to the structure with —OH on the right
D and L Monosaccharides • Stereochemistry determined by the asymmetric center
farthest from the carbonyl group
• Most monosaccharides found in living organisms are D
D D L
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Aldose
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Ketone Sugars Ketones are not easy to oxidize except for ketoses
Enediol reaction -- All monosaccharides are reducing sugars
CHO
OHH
HHO
OHH
OHH
CH2OH
OH
HHO
OHH
OHH
CH2OH
OH
O
HHO
OHH
OHH
CH2OH
OH
Aldose Ketosecis-enediolintermediate
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Ketose
Pure Fruits Sweetly Taste
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Conformation Intramolecular cyclization
Anomer
Mutaroation
Furanose & pyranose
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Cyclization of D-glucose
β-D-glucose
α-D-glucose CHO
OHH
HHO
OHH
OHH
CH2OH
OHOHO
OHOH
OH
OHOHO OH
OH
OH
C
OH
OH
OH
OH
CH2OH
OH
OH
O
H
HO
HOOH
OH
a b
OH
H
HO
OHO
H
HOHO
OHO
OH
OH
H
OH
OH
a
b
Intramolecular Cyclization Chain can bend and rotate
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Fisher Projections
Haworth Formulae
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Stereo Projections
Chair Presentations
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OH
O
OH
OH
OH
OH
Aldose(Glucose)
OH
OH
OH
OH
OH
OH
OH
O
OH
OH
OH
OH
O
OH
O
OH
OH
OH
OH
OH
O
OH
O
OH
OH
OH
OH
OH
Alditol(Glucitol)
Aldouronic Acid(Glucuronic Acid)
Aldaric Acid(Glucaric Acid)
Aldonic Acid(Gluconic Acid)
[H][O] C-1 and C-6
[O] C-6[O] C-1
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Pyranose: Chair, Boat, Half-chair, Skew.
O
123
4 5
4C1
O4 5
3 2 1
4C1
O1
234
5
1C4
O
1
23
45
1,4B
Furanose: Envelope, Twist. O
1E
O
1T
O
O
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COMPLICATION OF CARBOHYDRATE
1. Number of Carbon Atoms
2. The Location of Carbonyl Group
3. The Configuration of Sugar (D or L)
4. The Size of Ring (5, 6 or 7)
5. The Configuration at Position 1 (a or b)
6. The Connectivity between Sugar Units
7. Derivatives (oxidation, reduction, deoxy, various group)
CARBOHYDRATE ISOMERS Combination of Individual Units
Number of Carbohydrates
Two identical units, A-A dimer
11
Three identical units, A-A-A trimer
176
Three different units, A-B-C trimer
1,056
Five different units, A-B-C-D-E pentamer
2,144,640
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Starch Energy storage used by plant
Long repeating chain of a-D-glucose Chain up to 4000 units
Amylose Straight chain
Amylopectin Branched structure Major part of starch
Great for making gravy, jam & jelly
Starch can be found
Pasta, Rice , Potatos Bread
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Too much ….. Carbohydrate will be converted into fat and stored under the
skin leading to weight gain!