Digestion-Metabolism-of-CHO hydrates-all

Carbohydrates metabolism

1. DIGESTION & METABOLISM OF CARBOHYDRATE FOR RUMINANTS & NON-RUMINANTS Dr. Kaushalendra Kumar Assistant Professor (Animal Nutrition), Bihar Veterinary College, BASU, Patna, India E-mail: [email protected]

2. Digestion & absorption of carbohydrates in monogastric Salivary digestion in mouth Digestion in the gastrointestinal tract Main organ for the absorption of dietary nutrients by the monogastric mammal is small intestine (jejunum).

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4. Some common digestive enzymes with their sources & substrate Name of enzymes Systematic name Source Substrate Enzymes hydrolysing glycosidic linkages α-Amylase (Diastase) 1, 4-α-D-Glucan glucanohydrolase Saliva, pancreas Starch, glycogen, dextrin α-Glucosidase (Maltase) α-D-Glucoside glucohydrolase Small intestine Maltose Oligo-1,6-glucosidase (Iso-maltase) Dextrin 6-α-glucanohydrolase Small intestine Dextrin β-Galactosidase (Lactase) β-D-Galactoside galactohydrolase Small intestine Lactose β- Fructofuranosidase (Sucrase) β-D-Fructofuranoside fructohydrolase Small intestine Sucrose Credit: McDonald et al. (2011). Animal Nutrition.

5. Digestion and absorption of carbohydrates in ruminants

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8. Metabolism of carbohydrates There are three fundamental ways of metabolism of the absorbed CHO Being used as an instant source of energy. Serves as a precursor of liver and muscle glycogen. To assist as a precursor of tissue triglycerides.

9. Glycolytic pathway Cont....

10. TCA cycle Cont....

11. Pentose phosphate pathway Cont....

12. Glucose as a source of energy Galactose as a source of energy Fructose as a source of energy Glycogen as a source of energy Propionic acid as a source of energy Butyric acid as a source of energy Acetic acid as a source of energy Cont....

13. ATP yield from the complete oxidation of one mole of glucose Reactions High-energy bonds production ATP yield Glycolysis     Glyceraldehyde-3-phosphate dehydrogenase Resp. chain oxidation of 2 NADH 6 a Phosphoglycerate kinase Oxidation at substrate level 2 Pyruvate kinase Oxidation at substrate level 2     10 ATP consumption by hexokinase and phosphofructokinase -2 Net 8 Citric acid cycle     Pyruvate dehydrogenase Resp. chain oxidation of 2 NADH 6 Isocitrate dehydrogenase Resp. chain oxidation of 2 NADH 6 α-ketoglutarate dehydrogenase Resp. chain oxidation of 2 NADH 6 Succinate thiokinase Oxidation at substrate level 2 Succinate dehydrogenase Resp. chain oxidation of 2 FADH 2 4 Malate dehydrogenase Resp. chain oxidation of 2 NADH 6 Net 30 Total per mol of glucose under aerobic conditions 38 Total per mol of glucose under anaerobic conditions 2 a Assuming that NADH formed in glycolysis is transported to mitochondria via malate pathway. If the glycerophosphate pathway is used, only 2 ATP would be formed per mol of NADH, and a total net production are to be 36 instead of 38. Credit: Martin et al. (1983). Cont....

14. Glycogen metabolism Cont....

15. Propionate and acetate conversion to glucose Cont....

16. Formation of Acetyl-CoA from butyrate Cont....

17. THANKS Discussion.......... Questions, if any?