O1iii: Digestion & Absorption of protein
Definition
Proteins = long chains of amino acids bound by peptide linkages
Stomach
- PEPSIN is the peptic enzyme of the stomach
- pH 2 – 3= most active
- Parietal cells secrete large amounts of HCl which makes PEPSIN activity highly favourable
- Pepsin has the ability to digest collagen → major constituent of intercellular connective tissue of meats
- ~20% of protein digestion
- Hydrolyses some peptide linkages
Pancreas
- Most protein digestion occurs in upper SI
- By proteolytic enzymes of pancreas
- TRYPSIN, CHYMOTRYPSIN, CARBOXYPOLYPEPTIDASES, PROELASTASE
- Most to dipeptides & tripeptides
Enterocytes of Intestinal Villi
- Microvilli contain multiple peptidases
- AMINOPOLYPEPTIDASE & DIPEPTIDASE cleave remaining di & tripeptides into amino acids
- Amino acids are easily transported into enterocyte & absorbed