Protein Metabolism Flashcards
How much protein does a healthy adult require daily?
Why is this amount needed?
40-50g
To supply essential amino acids
Replace the N contained in amino acids that are converted to urea
Where does protein digestion and absorption mainly occur?
In duodenum
How many AA are found in the proteins we use?
How many are essential?
Only 20
8 are essential, cannot manufacture them
Where does protein digestion begin?
In the stomach
What happens in the stomach in protein digestion and what enzymes involved?
Pepsin cleaves some of the peptide linkages - forming peptide fragments
Where is pepsin secreted from?
Chief cells secrete pepsinogen which is rapidly activated by the low luminal pH to form pepsin
Where is pepsinogen I & II found?
Pepsinogen I - found only in HCl secreting regions (mainly body of stomach)
Pepsinogen II - found in the pyloric region
Where is protein broken down after the stomach?
In the duodenum/small intestine
What enzymes are released into the duodenum and from where?
Endo & exopeptidases
Produced in pancreas
Enzymes are inactive and are activated when secreted into duodenum
What do pancreatic endo and exopeptidases do?
Examples of each?
Endopeptidades - mid chain
Eg, trypsin & chymotrypsin & elastase
Exopeptidases- carboxypeptidase c=o
Membrane bound aminopeptidase (microvilli border)
How are proteins absorbed?
Secondary active transport with Na+ cotransporters
Basolaterally into interstitialfluid then capillaries
Where does protein absorption occur?
In small intestine
