1. Chapter 7 Carbohydrates and Glycobiology

2. Carbohydrates are everywhere http://www.homejoin.com.tw/newpic2000/HST-40.jpg http://www.cofc.edu/~delliss/virtuallabbook/LoadingGel/Minigel2a.jpg http://www.99main.com/~charlief/theeyebg.gif http://sportsdrz.com/images/knee.jpg

3. Sucrose http://graphics.stanford.edu/courses/cs348b-competition/cs348b-05/donut/fifthdonut.jpg http://www.solarnavigator.net/solar_cola/cola_images/sucrose_table_sugar_crystals.jpg glazed donuts Sucrose (table sugar)

4. What are carbohydrates? Carbo-hydrates are a group of organic compound that can usually represented as (CH 2 O) n. Glucose, fructose, and galactose are all carbohydrates.  -D-Galactose

5. Classification of carbohydrate –carbon number –L- or D- isomers –pyranose or furanose –α or β anomers –ketose or aldose

6. Carbon number In addition to simple hexose such as glucose, galactose, and mannose, there are a number of sugar derivatives in which a hydroxyl group in the parent compound is replaced with another substituent, or carbon atom is oxidized to a carboxyl group. Therefore, researchers must give each carbon of a sugar a number.

7. Carbon number HO C H C C H C H C H CH 2 OH HO OH CH 2 OH H C C H C H C H HO O OH CH 2 OH aldose ketose 1 2 3 4 5 6 1 2 3 4 5 6

8. L- and D- isomers CHO H | -C- | OH CH 2 OH CHO H | -C- | HO CH 2 OH -glyceraldehyde D L [  ] 25 D =+8.7 ˚ [  ] 25 D =-8.7 ˚

9. L- and D-isomers Although L- and D-isomers of glyceraldehydes are truly levo-rotatory (-) and dextro-rotatory (+), L- and D- sugars are NOT. For example, L-arabinose [  ] 20 D =+105.1 ˚ and D-fructose [  ] 20 D =-92 ˚  -L-arabinose (pyranose form)

10. How to determine L- and D- First, find the chiral carbon C H-=O | H--OH C H- -HC | | OH C

11. How to determine L- and D- If there is more than one chiral carbon, then… H-C H-C-OH | H 2 -C-OH | H-C-OH | =O H 2 -C-OH C=O H-C-OH H 2 -C-OH HO- | | | | -HC D- L-

12. C 5 Formation of the cyclic form HO H C C H C H H CH 2 OH HO OH C 1 C H HO O C H OHOH C HOH C H C HOHOH CH 2 OH 1 5 6  anomer

13. Other sugar generate 5-member ring C 5 H C C H C H CH 2 OH HO O OH 2 CH 2 OH H O C OH C HOH C H C HOCH 2 2 5 6 CH 2 OHOH CH 2 OH  anomer

14. (few)

20. The importance of a sialic acid a sialic acid Normal protein Asialo- glycoprotein: Will be removed by asialoglycoprotein receptors in the liver Sialidase (neuraminidase)

21. Monosaccharides Colorless, crystalline solids Water soluble but not soluble in nonpolar solvent Taste sweet

22. Monosaccharides have reducing powers http://www.uni-regensburg.de/Fakultaeten/nat_Fak_IV/Organische_Chemie/Didaktik/Keusch/Grafik/fehling2.gif

23. Disaccharide is made by joining two monosaccharides

24. Lactose is only present in milk

25. Sucrose is also called table sugar

26. Trehalose is a major constituent of insect hemolymph

27. 3 ≦ oligosaccharide ≦ 20

28. Polysaccharides Polysaccharides can serve as fuels, structural elements, and extracellular support.

30. Polysaccharides Homopolysaccharides –Starch (amylose, amylopectin) –Glycogen –Chitin Heteropolysaccharides –Peptidoglycan –Agar (agarose, agaropectin) –Glycosaminoglycans

31. Starch and glycogen are polymers of  -D-glucose The main chain of starch and glycogen are consisted of  -D-glucose joined by (  1  4) glycosidic bonds.

32. The branch point of starch and glycogen : (  1  6) Amylopectin and glycogen have branchs.

33. Cellulose is a polymer of  -D- glucose

35. amylose cellulose

36. Chitin : polymer of  -N-acetyl-D- glucosamine GlcNAc

37. Peptidoglycan contains heteropolysaccharides

38. Agarose is very important in molecular biology applications http://www.cofc.edu/~delliss/virtuallabbook/LoadingGel/Minigel2a.jpg

39. Glycosaminoglycans are heteropolysaccharides N-acetylglucosamine or N-acetyllgalactosamine + uronic acid (D- glucuronic or L-iduronic acid)

40. Heparin is a natural anticoagulant

41. Glycoconjugates Proteoglycans – glycosaminoglycan chains covalently joined to a membrane or secreted protein Glycoproteins – complex oligosaccharides covalently joined to a protein Glycolipids – membrane lipids with oligosaccharides as hydrophilic head

42. Proteoglycans Point of attachment Site of attachment Trisaccharide bridge

43. Proteoglycan aggregates

44. Glycoproteins Glycoproteins are carbohydrate-protein conjugates in which the carbohydrate moieties are smaller and more structurally diverse than the glycosaminoglycans of proteoglycans. Anomeric carbon of carbohydrate + -OH of Ser/Thr or –NH 2 of Asn

45. Glycophorin A Glycophorin A has 16 oligosaccharides covalently attached to it, with total 60 to 70 monosaccharide residues. It is the MN antigen of human erythrocytes. Ser1, Gly5  M

46. O- and N-linked glycosidic linkages

47. Glycolipid and lipopolysaccharides are membrane components

48. Glycobiology Carbohydrates can be served as informational molecules

49. Sugar serves as “aging” marker of proteins a sialic acid Normal protein Asialo- glycoprotein: Will be removed by asialoglycoprotein receptors in the liver Sialidase (neuraminidase)

50. Lectins Lectins are proteins that bind carbohydrates with high affinity and specificity.

52. Membrane lectins of H. pylori binds to membrane glycoprotein of gastric epithelial cell Membrane lectins (P-, E- and L- selectins) play important role in the movement of immune cells