Amino acid metabolism

Question 1

What happens to excess amino acids?

Answer 1

They go into an amino acid pool

Question 2

What are the key contributors to the amino acid pool

Answer 2

Diet= 100g/day
Breakdown= -100g/day
Biosynthesis= -250-300g/day
Body protein= store
Degradation= 250-300g

Question 3

What are the three destinations for AA in the pool?

Answer 3

1. Protein synthesis
2. Direct use
3. Breakdown and redeployment

Question 3

What is an overview of Amino acid breakdown?

Answer 3

Amino acids get converted into alpha-ketoglutarate
Transamination turns it into glutamate while deamination converts it to ammonia

Question 4

What is the general process of transamination

Answer 4

Amino acid and alpha ketoglutarate get modified by aminotransferase
They swap their amine group and oxygen double bonds forming a Keto acid and glutamate
What keto acid formed depends on the amino acid inputted

Question 5

What is the general equation for deamination?

Answer 5

The glutamate received from transamination (with one water molecule) is reduced by NAD+ reforming ketoglutarate and releasing NH4+ into the urea cycle

Question 6

How is the NH4+ converted to a product that can enter the urea cycle?

Answer 6

CO2 +NH4+ +H2O +2ATP => carbamoyl phosphate +2ADP +Pi

Question 8

Explain the urea cycle

Answer 8

Carbamoyl phosphate is incorporated with Ornithine and releases Pi and Citrulline
The citrulline is catalysed by ATP to combine it with Asparagine to form arginino-succinate
This is then broken down to fumarate and arginine