Presentation Topic.pptx by asmat ali on absorption of protein

absorption of protein

1. Hassaan Ahmad #27

2. Presentation Topic Absorption of Proteins

3. Group Members Hassaan Ahmad Abbas Khan Rashid Minhas Mohsin Khan Farooq Khalil Eishma Sana Khan Sobia Bushra Rehman Haseeba

4. Learning Objectives What are Proteins? Composition of Proteins. Digestion of Proteins. Absorption of Proteins. Absorption of Amino acids.

5. What are Proteins? Proteins are the most abundant organic molecule of the living system. It forms the fundamental basis of structure and function of life. They are macromolecules.

6. They constitute about 50% of the cellular dry weight. They are not only the cell building blocks; they also execute all the cell functions. Proteins are the polymers of amino acid.

7. Function of Proteins Protein performs a very great variety of specialized and essential functions in the living cells. These functions may be broadly grouped as Static (Structural) and Dynamic functions.

8. Composition Carbon = 50-55% Oxygen = 19-24% Nitrogen = 13% Hydrogen = 6-7% Sulfur = 4%

9. Amino Acid

10. Rashid Minhas #30

11. Digestion and Absorption Digestion: In chemical  digestion , enzymes break down food into the small molecules the body can use. (Chemical Digestion)

12. In the human digestive system, food enters the mouth and mechanical digestion of the food starts by the action of mastication (chewing), a form of mechanical digestion, and the wetting contact of saliva. (Physical Digestion).

13. Digestion in Mouth There is no digestion of protein in mouth because no proteolytic enzymes present in the saliva. Saliva only lubricate the food, this helps in making food soluble for the action of proteolytic enzymes.

14. Sana Khan

15. Digestion in Stomach Digestion of proteins starts in stomach. When proteins enters the stomach, it stimulates the secretion of gastrin hormone. This gastrin, in turn, stimulates the release of gastric juice which contains; Hydrochloric acid (HCL). Pepsinogen (zymogen). Rennin in infants. pH of gastric juice = 1.5 to 2.5

16. Role of gastric HCL It causes denaturation of proteins. It convert proteins to meta proteins which are easily digested. It converts pepsinogen to pepsin. It makes pH in the stomach suitable for the action of pepsin.

17. Role of Pepsin It is activated by HCl by auto activation . Its optimum pH is 1.5-2.2 It is an endo peptidases acting on the central peptide bond. It is secreted in active form called pepsinogen. Pepsinogen HCl Pepsin.

18. Role of Rennin It is a milk-clotting enzyme. It is present in the stomach of infants and young animals. Its optimum pH is 4. It converts casein of milk into paracasein . It combines with calcium forming calcium paracaseinate .

19. Syed Farooq

20. Digestion in Pancrease Trypsin : It is an endopeptidases and secreted in an inactive form called trypsinogen . Its optimum pH is 8. It is activated by entero -kinases. It hydrolyze central peptide bond in which the carboxylic group belongs to basic amino acid. Trypsinogen enterokinases Trypsin

21. Chymotrypsin It is the endopeptidase and secreted in an inactive form. Its optimum pH is 8. It is activated by trypsin . It hydrolyze the central peptide bond in which the carboxylic group belongs to aromatic amino acid.

22. Elastase It is also endopeptidases and secreted in an inactive form called proelastase . Its optimum pH is 8. It is activated by trypsin . It digests elastin and collagen. It hydrolyze the central peptide bond in which the carboxylic group belongs to aromatic amino acid.

23. Mohsin Khan #26

24. Carboxypeptidase Definintion : A carboxypetidase is a protease enzyme that hydrolyzes a peptide bond at the carboxy -terminal of a protein or peptide.

25. Funtions The first carboxypeptidases studied were those involved in the digestion of foods. e.g. Pancreatic Carboxypeptidases A₁,A₂, and B. However, most of the known carboxypeptidases is not involved in catabolism; they help to mature protein. e.g. the biosynthesis of neuroendocrine peptides such as insulin requires a carboxypeptidase .

26. Classfication by Substrate Preference This classification system for carboxypeptidases refers to their substrate preference. Carboxypeptidase A: Pancreatic exocarboxypeptidases that have a stronger preference for those amino acids containing aromatic or branched hydrocarbon chains are called carboxypeptidases A (A for aromatic or aliphatic).

27. Carboxypeptidase B: Those carboxypeptidases that cleave positively charged amino acids are called carboxypeptidase B (B for basic). e.g. arginine , lysine

28. Eishma

29. Digestion in Intestine Aminopeptidases : It is an exopeptidases . It acts on the terminal peptide bond at the amino terminal of the peptide chain. Dipeptidases : It acts on dipeptide. It releases two amino acids. Tripeptidases : It act on tripeptide . It releases single amino acid and dipeptide.

30. Absorption of Proteins It is an active process that needs energy. Energy needed is derived from hydrolysis From ATP. This process occurs in small intestine. Absorption of amino acids is rapid in the Duodenum and jejunum but slow in the Ileum.

31. Mechanism of Amino Acids Absorption There are two mechanisms of amino acids absorption. Carrier Protein Transport System. Glutathione Transport System ( Glutamyl Cycle).

32. Sobia

33. Carrier Protein Transport System It is the main system for amino acid absorption. It is an active process that needs energy. The energy needed is derived from ATP molecule. There are seven carrier proteins, one for each group of amino acids.

34. Each carrier protein has two sides. One for amino acid and another one for sodium. It co-transport s amino acids and sodium from intestinal lumem to cytosol of intestinal mucosa cells. The absorbed amino acid passes to the portal circulation, while sodium is extruded out of the cell with exchange with potassium (K+) by Sodum (Na+).

35. Bushra Rahman

36. Glutathione Transport System It is also known as Glutamyl Cycle. Glutathione is used to transport amino acids from intestinal lumen to cytosol of intestinal mucosa cells. It is an active process that needs energy. The energy needed is derived from ATP. Absorption of one amino acid molecule need 3 ATP.

37. Glutathione reacts with amino acid in the presence of glutacyl . Glutamyl amino acid releases amino acid in the cytosol of intestinal mucosa cell with formation of 5-oxoproline that is used for regeneration of glutathione to begin another turn of the cycle.

38. Oxoprolinuria : It is a disease caused by a defect in glutathione synthetase enzyme. It is characterised by accumulation of 5-oxoproline in blood and hence excreted in urine. It is associated with mental retardation.

39. Haseeba #28

40. Absorption of Intact Proteins and polypeptides This period is short period, immediately after birth. The small intestine of infants can absorb intact prroteins and polypeptide by endocytosis or pioncytosis .

41. Intact proteins and polypeptides are not absorbed by the adult intestine. Macromolecular absorption in certain individuals appears to be responsible for antibody formation that often causes food allergy.

42. Absorption of Amino Acids The absorption occurs mainly in the small intestine. It is an energy requiring process. The di- and tripeptidases , after being absorbed are hydrolyzed into free amino acids in the cytosol of epithilial cells. The activities of dipeptidases are high in these cells.

43. L-Amino acids are more rapidly absorbed than D-amino acids. The transport of L-amino acids occurs by an active process. D-amino acids by a simple diffusion.

44. Mechanism of absorption of amino acids Na+ dependant active process and requires ATP. Na+ diffuses along the concentration gradient. The amino acid also enters the intestinal cell. Na+ and amino acids share a common carrier and transported together. The compound ‘ cytochlasin ’ inhibits Na+ independent transport system.

45. Abbas Khan #33

46. Summary Digestion of Proteins. Absorption of Proteins.

47. The END