Amino Acid Metabolism Flashcards
Proteases in lysosomes are called
cathepsins
Which proteins do lysosomes degrade during starvation?
During starvation, lysosomes selectively degrade proteins in tissues that atrophy in response to fasting (kidney, liver). Not in brain.
What is the first step in amino acid catabolism?
removal of an amino group
Problem with removing NH3 from amino acids?
NH3 is toxic.
Cannot be permitted to accumulate.
In mammals, what does the liver convert amino groups into?
Urea (non toxic)
What do reptiles and birds make instead of urea?
uric acid
How do fish deal with ammonia?
fish continuously dump ammonia
Where do the nitrogens from amino acids burned in the muscle go?
N’s added to pyruvate to make alanine, which is sent to the liver.
This is how it can be transported to the liver through the blood without making toxic ammonia
Where do the nitrogens from amino acids burned in non-muscle tissues go?
sent to the liver as gln
What happens to the amino groups in amino acids in the liver?
the amino groups from amino acids in the liver are transferred to a-kg, yielding glutamate and the a-keto acid of that particular amino acid
Where does the deamination of glu occur?
in the liver ONLY
What does the liver do with the alanine sent by the muscle?
- remove the amino group yielding pyr
- run gluconeogenesis
- ship glucose back to muscle
GLUCOSE-ALANINE CYCLE
What does the liver do with the glutamine sent by non-muscle tissue?
-remove the amide
-make urea
DEAMIDATION RXN (not eamination, not transamination)
Where in the cell does the Urea Cycle take place?
Some reactions in the mito and some in the cyto
Carbamoyl phosphate synthase has a high affinity for _____.
Carbamoyl phosphate synthase has a high affinity for AMMONIA.
Will consume ammonia if the concentration gets too high.
