1. Digestion of Biomolecules
Stryer Short course
Chapter 14

2. Hydrolysis Reactions Proteins amino acids
Proteases, peptidases
Complex carbohydrates  monosaccharides
amylase
Triacylglycerides  fatty acids
lipase

3. Zymogens Proenzymes—inactive precursors
Cannot release digestive enzymes everywhere!
Pepsinogen  pepsin: autocatalysis at low pH

4. Pancreatic Zymogens

5. Mechanism
Protease activates trypsin
Trypsin activates other zymogens

6. Stomach Highly acidic, denaturing environment Pepsin begins work
Acidic, partially digested food enters intestine
Activates secretin to neutralize adic
Activates hormone causing release of pancreatic zymogens and bile salts

7. Stomach acid
Prilosec: irreversible inhibitor of proton, potassium pump
Error in carbonic anhydrase

8. Proteins in the Intestine
Protein digestion continues with proteases in lumen
Transporter proteins essential—basis of some genetic diseases
Amino acids then sent to liver
Gluten sensitivity

9. Carbohydrates in the Intestine
a-amylase
Limiting dextrins
Maltase, sucrose, lactase, glucosidase, dextrinase all work to digest to monosaccharides

10. Carbohydrate Transporters

11. Lipid Digestion Complicated by insolubility Emulsion form in stomach
Extra steps of degradation/re-assembly
Bile salts
Cholesterol lowering medications

12. Pancreatic Lipases
Zymogens
Fatty acids and MAG
Miscelle formation

13. Transport to Liver Fatty acid binding proteins
Fatty acid transport proteins
Smooth enoplasmic reticulum
chylomycrons