Digestion and Absorption of Proteins

Where are the sites of Protein Digestion?

Stomach and small intestines

What are the enzymes in the stomach called

Enzyme is released by chief cells of the stomach

This enzyme is called pepsinogen

It is made active by the action of HCl to pepsin

What are the enzymes in the small intestine?

Trypsinogen———Trypsin

Chymotrypsinogen——— Chymotrypsin

Proelastase———-Elastase

Procarboxypeptidase———Carboxypeptidase

What are the Pancreatic Enzyme type and catalytic mechanism

Type: Endopeptidase

Mechanism: Serine protease

Trypsin

Chymotrypsin

Elastase

Type:Carboxypeptidase

Mechanism: Metalloprotease

Carboxypeptidase A

Carboxypeptidase B

Outline the Pancreatic Enzyme Cleavage Specificity

Trypsin: Peptide bonds adjacent to basic amino acids

Chymotrypsin: Peptide bonds adjacent to hydrophobic amino acids

Elastase: Peptide bonds adjacent to small amino acids

Carboxypeptidase A: Hydrophobic amino acids at C terminus

Carboxypeptidase B: Basic amino acids a the C terminus

What are the products of Protein Digestion?

Amino Acids

Di-peptides

Tri-peptides

Tetra-peptides

What are the absorption mechanisms?

Passive Diffusion

Facilitated diffusion

Active Transport

How are peptides absorbed

Entry into the enterocyte: Majority of protein is absorbed