1. Biochemistry Sixth Edition
Berg • Tymoczko • Stryer
Chapter 11:
Carbohydrates
Copyright © 2007 by W. H. Freeman and Company

2. Carbohydrates Common terms
Monosaccharides: glucose, fructose, mannose, etc.
Disaccharides: maltose, cellibiose, sucrose, lactose
Polysaccharides: starch, glycogen, chitin, glycosaminoglycans
Aldoses, ketoses
Pentoses, hexoses
Pyranose, furanose
Anomeric carbon atom, anomers, a, b
D,L isomers, epimers, penultimate carbon
Glycosidic bond, hemiacetal, acetal
Mutarotation
Reducing sugar

3. Trioses (three carbons)
* Know * *
aldose aldose ketose

4. *
Adlose family
Aldose family
* Know * * * *

5. *
Ketose family
Ketose family
* Know * *

6. D-Stereochemistry of Glucose
Convention for the Fischer projection:
Carbonyl (#1C) is at the top.
OH to right = "D"
OH to left = "L"
Glucose is assigned the D stereochemistry because the penultimate carbon atom is D.

7. Hemiacetal formation

8. Pyranose and Furanose forms
Hemiacetal,
Haworth
structure
Hemiketal,
Haworth
structure

9. Haworth Structure of Glucose
Draw Fischer, rotate 90o,
then form the hemiacetal
a-anomer
b-anomer

10. Haworth Structure of Fructose

11. Ribose and Deoxyribse
Haworth structures

12. Mutarotation of Fructose
Open
chain
form

13. Mutarotation of Glucose
b-D-glucofuranose
~0.5%
a-D-glucofuranose
~0.5%
Open
chain
Form
~0.003%
a-D-glucopyranose
36%, aD = 112o
b-D-glucopyranose
63%, aD = 18.7o
Observed rotation = 52.7o

15. Glycosidic bond (acetal)

16. Three glucose residues
The connections (gycosidic bonds) are (a 1-4)

17. Lobry de Bruyn-Alberda von Eckenstein rearrangement
Reaction
of a sugar
in NaOH.

18. Methylation of Glucose
Converting a hemiacetal to an acetal.

19. Methylation of Glucose
Exhaustive methylation forms one glycocidic bond and the rest are ethers.

20. Sugar Derivatives
Also, oxidized or reduced or phosphorylated or amino sugars

21. Sugar Oxidation at C-1
Gluconic
acid

22. Sugar Oxidation at C-6

23. Sugar Phosphates

24. N-Acetylmuramic acid N-acetylglucosamine + lactate,
A component of bacterial cell wall.

25. N-Acetylneuraminic acid
N-acetylmannosamine + PEP

26. Common disaccharides
The anomeric OH in 1, 2, & 3 may be a or b, but sucrose may not.
Maltose:
a-D-glucopyranosyl-(14)-a-D-glucopyranose
2. Cellibiose:
b-D-glucopyranosyl-(14)-a-D-glucopyranose
Lactose:
b-D-galactopyranosyl-(14)-a-D-glucopyranose
4. Sucrose:
a-D-glucopyranosyl-(12)-b-D-fructofuranoside

27. Maltose, a disaccharide

28. Other disaccharides
Cellibiose

29. Common Homopolysaccharides
Amylose (linear starch)
An a-(14)-D-glucose polymer
2. Cellulose (linear)
A b-(14)-D-glucose polymer
Amylopectin (branched starch)
An a-(14)-D-glucose polymer branched a-(16)
Glycogen (branched)
Chitin (linear)
An b-(14)-D-N-acetylglucosamine polymer

30. Glucopolysaccharides
Homopolysaccharides

31. A 1-6 branch point This branch occurs in glycogen and amylopectin.
However, glycogen is more highly branched.

32. A high energy glucose carrier

33. Heteropolysaccharides
Glycosaminoglycans
(disaccharide repeating units)
Chondroitin-6-sulfate:
-D-glucuronic acid-(b 13)-N-acetyl-D-galactosamine-6-sulfate-(b 14)-
Keratan sulfate:
-D-galactose-(b 14)-N-acetyl-D-glucosamine-6-sulfate-(b 13)-

34. Heteropolysaccharides
Glycosaminoglycans
(disaccharide repeating units)
Dermatan sulfate:
-L-iduronic acid-(b 13)-N-acetyl-D-galactosamine-4-sulfate-(b 14)-
Hyaluronic acid:
-D-glucuronic acid-(b 13)-N-acetyl-D-glucosamine-(b 14)-

35. A Proteoglycan A glycoconjugate:
(polysaccharide linked to a protein or peptide)

36. Proteogycan
Electron
micrograph

37. Complex Carbohydrates

38. L-Fucose
L-fucose is 6-deoxy-L-galactose

39. Linkages in Glycoproteins

40. N-Linked Carbohydrate
High mannose

41. N-Linked Carbohydrate
Complex carbohydrate

43. Dolichol phosphate (isoprenoid)
This is the endoplasmic reticulum membrane anchor on which the core carbohydrate for a glycoprotein is synthesized. It is then modified in a Golgi body.

45. From Golgi to Lysosome
Mannose-6-P is a marker that directs some hydrolytic proteins from a Golgi body to a lysosome where glycolipids and glycosaminoglycans are degraded.

46. Hydrolysis of the
N-acetylglucosamine to leave a Mannose-6-P residue.

47. Review - Glycoconjugates
Proteoglycans (glycosaminoglycans + protein).
Mostly carbohydrate (~85%), e.g. cartilage
Glycoproteins (most 1-10% carbohydrate) N and O linked complex carbohydrates
e.g. receptors
Peptidoglycans (carbohydrate + small peptide). e.g. bacterial cell wall

48. Proteoglycan
Sketch

49. Peptidoglycan Bacterial cell wall (murein): A long linear polymer of:
-N-acetyl-D-glucosamine-(b 14) -N-acetyl- Muramic acid-(b 14)-
A tetrapeptide is attached through the carboxyl of the lactate moiety of muramic acid.
Lactate-CO-L-Ala-D-isoGlu-L-Lys-D-Ala-

50. Peptidoglycan Bacterial cell wall:
Lactate-CO-L-Ala-D-isoGlu-L-Lys-D-Ala-
In gram (+) bacteria crosslinks are formed by a pentaglycine bridge from the D-Ala residue above to the L-Lys in another peptide. (Outer surface is carbohydrate)
In gram (-) bacteria crosslinks are formed by a direct link from the D-Ala residue above to the L-Lys in another peptide. (Outer surface is cell membrane)

51. Gram Positive (+) Cell Wall
Up to 20 layers of peptideglycan

52. Gram Negative (-) Cell Wall
Monolayer of peptideglycan

53. Biochemistry Sixth Edition
Berg • Tymoczko • Stryer
End of Chapter 11
Copyright © 2007 by W. H. Freeman and Company