W6 A Protein Metabolism Amino Acids (AA)

Question 1

• How do dietary proteins get digested in Amino Acids?

give the organ where is occurs and what helps with digestion

Answer 1

Stomach (proteins to polypeptides)
- HCL
- Pepsin
Pancreas 
- Peptidases 
Small intestine (polypeptides to amino acids)
- Peptidases
-  Absorbed as amino acids

Question 2

• How many AA do we have in the body?

- What are AA comprised of?

Answer 2

• We have 20 AA in the human protein

- Carbon, Hydrogen, Oxygen, Nitrogen (amino group) and R group (specific)

Question 3

AA Fed State:

- What happens to AA whilst the body is in the fed state?

Answer 3

• AA arrive at the liver via hepatic ported vein

- Then protein synthesis occurs, transported to other tissues (muscles, membranes) and its stored (TAG)

Question 4

AA Fasted State:

- What happens to AA whilst the body is in a fasted state?

Answer 4

• The body needs to make energy

- It breaks down AA (Muscles functional proteins & Carbon skeleton)

Question 5

Alpha Keto (a-Keto) Acids:
- What is the difference between AA and a-Keto acids?

Answer 5

• They are not comprised of the same materials (they are similar but not the same)
• AA have NH2 and an extra H whereas, a-Keto acids only have an extra O.

Question 6

• What are Alpha Keto (a-Keto) Acids comprised of?

- What cycle do these feed into?

Answer 6

• Carbon
• Hydrogen
• Oxygen
• R group (specific)
  These feed into the TCA cycle

Question 7

• What’s the most common way to remove N from AA?

Answer 7

• Transaminate the AA with an a-Keto acid and move N from AA to a-Keto.

Question 8

• What is deamination through dehydrogenase?

Answer 8

• When AA and a-Keto acids remove N

Question 9

• What is the definition of transamination?
• Are transamination reactions freely reversible?
• What tissues does it occur in?

Answer 9

• It is the transfer of an amino group from AA to an a-keto acid in the presence of a transaminase.
• Transamination is a freely reversible reaction depending on substrate availability
• Transamination occurs in most tissues especially muscles.

Question 10

Name the three main transamination reactions:

Answer 10

1. Alanine - pyruvate
2. Aspartate - oxaloacetate
3. Glutamate - Alpha Keto glutrate

Question 11

• What is oxidative deamination?

Answer 11

• The removal of ammonia group

Question 12

Glutamine Synthase:

- What do you make glutamine from?

Answer 12

• Glutamine made from glutamate

Question 13

Glutamine Synthase:

- Glutamine is a great fuel for…

Answer 13

• GI tract & immune system

Question 14

Nitrogen Excretion:

- What state does the body have to be in to produce a lot of ammonia?

Answer 14

• The body produces a lot of ammonia whilst in a catabolic state because we remove nitrogen (ammonia) during exercise

Question 15

The Urea Cycle:

What are some key points of the urea cycle?

Answer 15

• This cycle is an irreversible reaction
• Aspartate enters (AA) and bring nitrogen
• An increase in AA will increase the urea out

Question 16

• What are branched chain AA or BCAA?

Answer 16

• They have a branched structure

- They can only be oxidised in skeletal muscle in the mitochondria

Question 17

What are three key branched chain AA or BCAA?

Answer 17

1. Leucine
2. Isoleucine
3. Valine

Question 18

• The important AA Alanine has a one main role, what is it?

- Where is Alanine taken up by and released from?

Answer 18

• Important for inter tissue transfer

- It is taken up by the liver and released from the muscles

Question 19

Why is the Alanine Cycle important?

Answer 19

• It’s important because transfers glucose to the necessary tissues.
• It also maintains glucose levels in the blood & liver.