1. AJI SUTRISNO FOOD SCIENCE AND TECH UNIVERSITAS BRAWIJAYA
HEXOSE METABOLISM
AJI SUTRISNO
FOOD SCIENCE AND TECH
UNIVERSITAS BRAWIJAYA

2. Common Hexoses

3. Sources of Sugars Glucose: lactose (dairy products) and
sucrose (table sugar)
Fructose: fruits and sucrose
Galactose: lactose
Mannose: polysaccharides and
glycoproteins

4. Fructose Metabolism

5. Sucrose (Table Sugar)
O-a-D-Glucopyranosyl-(1—> 2)-b-D-Fructofuranoside

6. All Tissues

7. Cleavage of Sucrose (a-glucosidase or invertase)

8. Mutarotation of Fructose

9. Muscle Metabolism of Fructose (Anaerobic Glycolysis) Large Amounts of Hexokinase

10. Liver Metabolism of Fructose I (Little Hexokinase)

11. Liver Metabolism of Fructose II

12. Mechanism of Aldolase (Formation of Schiff Base)

13. Mechanism of Aldolase (Aldol Cleavage Reaction)

14. Mechanism of Aldolase (Formation of Dihydroxyacetone-P)

15. Liver Metabolism of Fructose III

16. Complexity of Liver Metabolism
Breakdown of Many Metabolites

17. Fructose Intolerance Too Much Fructose
Fructose-1-P Aldolase is rate-limiting
Depletion of Pi
Reduction in [ATP]
Increase in glycolysis
Accumulation of lactate (acid) in blood
Fructose-1-P Aldolase Deficiency (Genetic Disease)

18. Galactose Metabolism

19. Lactose Metabolism (Dairy Products)

20. Mutarotation of b-D-Galactose

21. Glycolytic Enzymes are specific and do not recognize galactose!

22. Need Epimerization

23. Phosphorylation of Galactose

24. Activation of Galactose

25. Epimerization of UDP-Galactose

26. Mechanism of Epimerization

27. Glycoproteins Glycolipids (Require UDP-Galactose)
Why UDP-Galactose?
Glycoproteins
Glycolipids
(Require UDP-Galactose)

28. Formation of Glucose-1-P

29. Formation of Glucose-6-P
Glucose-6-P ——> Glycolysis

30. Galactosemia (Mental Retardation and Death)
Treatment
Galactose-free diet
(reversal of all symptoms except mental retardation)

31. Cataracts

32. Mannose Metabolism

33. Phosphorylation of Mannose

34. Isomerization of Mannose-6-P

35. THANK YOU

36. Mechanism of Isomerization

37. Aldoses and Ketoses

38. Mutarotation of Glucose

39. Mutarotation of Fructose