2. Storage Pentose phosphate pathway (oxidation) Glycolysis (oxidation) Glycogen, Starch, Sucrose Pyruvate Ribose 5-phosphate

3. Eduard Buchner (1860-1917) 1897 found fermentation in broken yeast cells 1907 Nobel Prize in Chemistry

4. The whole pathway in yeast and muscle cell were elucidated by Arthur Harden 1865-1940

7. Glycolysis Glycolysis is an almost universal central pathway of glucose catabolism, the pathway with the largest flux of carbon in most cells. In some mammalian tissues (erythrocytes, renal medulla, brain, sperm), the glycolytic breakdown of glucose is the sole source of metabolic energy.

8. Glycolysis Some of the starch-storing tissues, like potato tubers, and some aquatic plants derive most of their energy from glycolysis. Many anaerobic microorganisms are entirely dependent on glycolysis.

9. 1. phosphorylation of glucose G 6-P

10. 2. Isomerization of glucose 6-phosphate G 6-PF 6-P

11. 3. Phosphorylation of fructose 6- phosphate: the first committed step in glycolysis F 6-P F 1,6-BP

12. 4. Cleavage of fructose 1,6- bisphosphate F 1,6-BP DHAP G 3-P

13. 5. Interconversion of the triose phosphate

14. 6. Oxidation of glyceraldehyde 3-phosphate to 1,3-bisphosphoglycerate 1,3-BPG

15. 7. Phosphoryl transfer from 1,3- bisphosphoglycerate to ADP 3-PGA

16. Substrate-level phosphorylation soluble enzymes chemical intermediates Respiration-linked phosphorylation Photophosphorylation membrane-bound enzymes transmembrane gradients of protons The formation of ATP by phosphoryl group transfer from a substrate is referred to as a substrate-level phosphorylation

17. Substrate-level phosphorylation

18. Respiration-linked phosphorylation or Photophosphorylation H+H+ H+H+ ATP ADP

19. Glyceraldehyde 3-phosphate dehydrogenase and Phosphoglycerate kinase are coupled in vivo Glyceraldehyde 3-phosphate dehydrogenase catalyzes an endergonic reaction while phosphoglycerate kinase catalyzes an exergonic reaction. When these two reactions are coupled (which happens in vivo), the overall reaction is exergonic.

20. Glyceraldehyde 3-phosphate dehydrogenase Phosphoglycerate kinase G 3-P Pi NAD+ 1,3-BPG NADH ADP 3-PGAATP

21. 8. Conversion of 3- phosphoglycerate to 2- phosphoglycerate 2-PGA

22. The phosphoglycerate mutase reaction

23. 3-phosphoglycerate2,3-bisphosphoglycerate2-phosphoglycerate Phospho- glycerate mutase COO- | HCOH | CH2O

24. 9. Dehydration of 2- phosphoglycerate to phosphoenolpyruvate PEP

25. 10. Transfer of the phosphoryl group from phosphoenolpyruvate to ADP

27. Glucose + 2ATP + 2NAD + + 4ADP + 2Pi  2 pyruvate + 2ADP + 2NADH + 2H + + 4ATP + 2H 2 O Glucose + 2ADP + 2NAD + + 2Pi  2 pyruvate + 2ATP + 2NADH + 2H + 在有氧狀況下，產生的 NADH 很快就被送 到 mitochondria 中用來合成 ATP

28. F 1,6-BP DHAP G 3-P aldolase pyruvateATP pyruvate 2-PGA 3-PGA 2-PGA ATP3-PGANADH + H + 1,3-BPG NAD + Pi F 1,6-BP G 6-P F 6-P Phosphohexose isomerase G 6-P ADP ATP glucose ADP Hexokinase Mg 2+ F 6-P ATP PFK-1 Mg 2+ DHAP G 3-P 1,3-BPG G 3-P NADH + H + 1,3-BPG ADP 1,3-BPG ADP 3-PGA ATP 2-PGA H2OH2O PEP H2OH2O ADP Pi NAD + 3-PGA 2-PGA enolase Phospho- Glycerate mutase Pyruvate kinase Phospho- glycerate kinase Triose Phosphate isomerase Glyceraldehyde 3-phosphate dehydrogenase Mg 2+

29. NAD + (nicotinamide adenine dinucleotide) is the active form of niacin

30. Niacin is the common name for nicotinamide and nicotinic acid. Nicotinic acid is the common precursor for NAD + and NADP + biosynthesis in cytosol. Niacin (Vitamin B3)

31. Functions of NAD + and NADP + Both NAD + and NADP + are coenzymes for many dehydrogenases in cytosol and mitochondria NAD + is involved in oxidoreduction reactions in oxidative pathways. NADP + is involved mostly in reductive biosynthesis.

32. Weight loss, digestive disorders, dermatitis, dementia Niacin deficiency: pellagra

33. Niacin deficiency Because niacin is present in most of the food and NAD + can also be produced from tryptophan (60 grams of trptophan  1 gram of NAD + ), so it is not often to observe niacin deficiency. However, niacin deficiency can still be observed in areas where maize is the main carbohydrate source because maize only contain niacytin, a bound unavailable form of niacin. Pre-treated maize with base will release the niacin from niacytin.

34. Niacin deficiency Areas where sorghum is the main carbohydrate source will also observe niacin deficiency if niacin uptake is not being watched carefully. Sorghum contains large amount of leucine, which will inhibit quinolinate phosphoribosyl transferase (QPRT), an enzyme involved in NAD + biosynthesis from tryptophan. Vitamin B6 deficiency can also lead to niacin deficiency because pyridoxal phosphate is a coenzyme in NAD + biosynthesis from tryptophan.

35. Feeder pathways for glycolysis p.535

36. Stored glycogen and starch are degraded by phosphorolysis Glycogen and starch can be mobilized for use by a phosphorolytic reaction catalyzed by glycogen/starch phosphorylase. This enzyme catalyze an attack by Pi on the (  1  4) glycosidic linkage from the nonreducing end, generating glucose 1-phosphate and a polymer one glucose unit shorter. p.535

37. p.536

38. Branch point (  1  6) is removed by debranching enzyme p.536

39. PPPPPPPP phosphorylase Transferase activity of Debranching enzyme  -1,6 glucosidase activity of Debranching enzyme

40. Digestion of dietary polysaccharides Digestion begins in the mouth with salivary  -amylase hydrolyze (attacking by water) the internal glycosidic linkages. Salivary  -amylase is then inactivated by gastric juice; however pancreatic  - amylase will take its place at small intestine. The products are maltose, maltotriose, and limit dextrins (fragments of amylopectin containing  1  6 branch points. p.535

41. Endo (  -amylase) and exo enzymes

42. Digestion of dietary disaccharides Disaccharides must be hydrolyzed to monosaccharides before entering cells. Dextrin + nH 2 O  n D-glucose Maltose + H 2 O  2 D-glucose Lactose + H 2 O  D-galactose + D-glucose Sucrose + H 2 O  D-fructose + D-glucose Trehalose + H 2 O  2 D-glucose dextrinase maltase lactase sucrase trehalase p.535

43. Lactose intolerance Lactose intolerance is due to the disappearance after childhood of most or all of the lactase activity of the intestinal cells. p.535-6

44. Lactose intolerance Undigested lactose will be converted to toxic products by bacteria in large intestine, causing abdominal cramps and diarrhea. p.535-6

45. 2 NADH4 ATP ADPF 1,6-BPADPF 6-P ATP Fructose metabolism in muscle and kidney Fructose hexokinase Mg 2+ F 6-P ATP PFK-1 F 1,6-BP Glycolysis p.536

46. F 1-P G 3-P DHAP ADP DHAP glyceraldehyde Fructose 1-phosphate aldolase G 3-P ATP ADPF 1-P ATP Fructose metabolism in liver Fructose fructokinase glyceraldehyde Triose kinase Mg 2+ Triose phosphate isomerase p.536

47. UDP-GlcNAD + NADH G 1-PUDP-Gal Gal 1-PADP ATP Galactose metabolism (p.536,537) Galactose is phosphorylated by galactokinase in the liver. Then galactose 1-phosphate is converted to glucose 1-phosphate by a series of reactions. galactose galactokinase Mg 2+ Gal 1-P UDP-Glc UDP-glucose: Galactose 1-P uridylyltransferase UDP-Gal NAD + UDP-glucose 4-epimerase

48. Epimer and epimerase (p. 241) Two sugars that differ only in the configuration around one carbon atom are called epimers. Enzymes that catalyze inversion of the configuration about an asymmetric carbon in a substrate having more than one center of asymmetry are called epimerases.

49. CHO | HO-C-H H-C-OH | CH2OH | HO-C-H | H-C-OH | CHO | HO-C-H | H-C-OH | CH2OH H-C-OH | mannoseD- glucoseD- 1 2 3 4 5 6 1 2 3 4 5 6 D-Mannose is a C2-epimer of D-glucose

50. Galactosemia inability to metabolize galactose due to lack of 1. UDP-glucose galactose 1-phosphate uridylyltransferase (classical galactosemia) 2. UDP-glucose 4-epimerase 3. Galactokinase Among these, deficiency of either 1 or 2 is more severe (1 is the most severe). p.537

51. Galactosemia Deficiency of transferase (or epimerase) will result in poor growth, speech abnormality, mental deficiency, and (fatal) liver damage even when galactose is withheld from the diet. p.537

52. Man 6-P F 6-P ADP Mannose metabolism mannose ATP Hexokinase Mg 2+ Man 6-P Phosphomannose isomerase p.537

54. Fermentation Fermentation is referring to the process when no oxygen is consumed or no change in the concentration of NAD + or NADH during energy extraction. p.538

55. Fermentation Under hypoxic conditions, oxidative phosphorylation will be the first to stop. Then citric acid cycle will come to a halt due to inhibition effect from NADH. As a result, glycolysis will be the only metabolic pathway that is available to energy production during hypoxia.

56. n ATP n ADP FAD2 NAD + 2 ATP2 FADH 2 6 NADH4 CO 2 2 ADP 2 Acetyl-CoA 2 FAD 6 NAD + 2 CO 2 2 ATP 2 ADP 2 pyruvate2 NADH Fermentation However, the oxidation of glyceraldehyde 3- phosphate consumes NAD + that will not be regenerated under hypoxic condition because oxidative phosphorylation is not available. Glucose 2 NAD + Glycolysis 2 acetyl-CoA2 NADH 2 NAD + PDH Citric Acid cycle 2 NADH 6 NADH 2 FADH 2 Oxidative phosphorylation

57. 2 NAD + 2 lactate2 NAD + 2 NADH 2 pyruvate 2 NADH2 pyruvate2 ATP The purpose of fermentation is to regenerate NAD + In order to continue regenerating NAD +, cells come up a strategy. During fermentation, NAD + is regenerated during the reduction of pyruvate, the product of glycolysis. glucose 2 NAD + 2 ADP glycolysis fermentation 2 lactate2 NAD + 2 NADH 2 pyruvate 2 NADH2 pyruvate2 ATP glucose 2 NAD + 2 ADP glycolysis fermentation 2 lactate2 NAD + 2 NADH 2 pyruvate 2 NADH2 pyruvate2 ATP glucose 2 ADP glycolysis fermentation

58. Lactate fermentation glycolysis

59. 2ATP Lactate is being recycled in liver (Cori cycle) muscleliver glucose 2 pyruvate 2 lactate 2 pyruvate 6 ATP glucose

60. Carl and Gerty Cori, 1947 Nobel Prize in Physiology and Medicine

61. Lactate fermentation only happened in larger animals Most small vertebrates and moderate size running animals have circulatory systems that can carry oxygen to their muscles fast enough to avoid having to use muscle glycogen anaerobically.

62. http://www.mountain-research.org/CV/coelacanth.jpg http://www.anac.8m.net/Images/coelacanth.jpg Deep sea fish (below 4,000 m or more) coelacanth uses anaerobic metabolism exclusively. The lactate produced is excreted directly. Some marine vertebrates can do ethanol fermentation.

63. Ethanol fermentation Yeast and other microorganisms ferment glucose to ethanol and CO 2. Pyruvate is first decarboxylated by pyruvate decarboxylase, which is absent in vertebrate tissues and in other organisms that carry out lactic acid fermentation. Acetaldehyde is the product of this reaction.

64. Pyruvate decarboxylase The decarboxylation of pyruvate by pyruvate decarboxylase produces CO 2, which is the reason why champagne is bubbling.

65. Thiamine pyrophosphate (TPP) is the coenzyme of pyruvate decarboxylase Thiamine pyrophosphate is derived from vitamin B1 (thiamine). Lack of vitamine B1 will lead to beriberi (edema, pain, paralysis, death; Singhalese “I cannot” Signifying the person is too ill to do anything.).

66. Alcohol dehydrogenase catalyze the second step of ethanol fermentation Alcohol dehydrogeanse reduces acetaldehyde, producing NAD + and ethanol. This enzyme is present in many organisms that metabolize ethanol, including human.

67. Fermentation has commercial values Bacteria like Lactobacillus bulgaricus (yogurt) and Propionibacterium freudenreichii (swiss cheese) ferments milk to produce lactic acid or propionic acid and CO 2.

68. Dr. Chaim Weizmann 1874-1952 First President of Israel Found butanol and acetone fermentation in Clostridium acetobutyricum

69. Industrial fermentation is done in huge close vats Fermentors are huge closed vats in which temperature and access to air are adjusted to favor the multiplication of the desired microorganism. Some even immobilize the cells in an inert support so no effort is required to separate microorganisms from products after fermentation is completed.