Protein Metabolism Flashcards
(56 cards)
What is denaturation?
The unfolding of protein’s structure, often due to acid, heat or enzymes
What is proteolysis?
Enzymatic breakdown of proteins into peptides or amino acids
Where does protein denaturation mainly occur?
In the stomach
Which enzyme starts protein digestion in the stomach?
Pepsin
What kind of enzyme is pepsin?
An endopeptidase
Which enzymes act in the small intestine to digest proteins?
Trypsin and chymotrypsin
What are endopeptidase?
Enzymes that cleaves amino acids from internal peptide bonds
What are exopeptidases?
Enzymes that cleave amino acids from the ends of peptide chains
How do amino acids enter cells?
Via carrier protein mediated active transport
What happens after amino acids enter the cell?
The amino group is removed by deamination
What is deamination?
Removal of the amino group from an amino acid
What does deamination produce?
Ammonia and a carbon skeleton
What is transamination?
Transfer of an amino group to α-ketoglutarate to form glutamate
Which enzyme catalyses transamination?
Aminotransferase
What is oxidative deamination?
Removal of an amino group from glutamate to form ammonia
What enzyme catalyses oxidative deamination?
Glutamate dehydrogenase
Where does oxidative deamination mainly occur?
In the liver
Which two amino acids can be directly deaminated?
Serine and threonine
Why can serine and threonine be directly deaminated?
They have a hydroxyl group on the β-carbon
What happens to the carbon skeleton after deamination?
It’s converted into metabolic intermediates
What are the 7 metabolic intermediated derived from AAs?
- Acetyl-CoA
- Acetoacetyl-CoA
- Pyruvate
- α-ketoglutarate
- Succinyl-CoA
- Fumarate
- Oxaloacetate
What are ketogenic amino acids?
AAs that form ketone bodies like acetoacetate
What are glucogenic amino acids?
AAs that form glucose via gluconeogenesis
Which amino acids are purely ketogenic?
Leucine and lysine
