Week 10 - Protein Metabolism (ELE content only)

Question 1

What part of the aa will provide us with energy?

Answer 1

Carboxylic group

Small % tho

Question 2

What happens in transamination reactions?

Answer 2

Amino group from 1 aa is transferred to glutamate.

Question 3

What enzyme carries out transamination

Answer 3

Aminotransferase

Question 4

What happens to the remaining carbon skeleton in a transamination reaction?

Answer 4

Becomes an alpha keto acid

useful for the TCA cycle

Question 5

Can transamination reactions be reversible for essential aa? WHY?

Answer 5

No

Can’t synthesise their carbon skeletons.

Question 6

Give examples of aa-specific aminotransferases

Answer 6

Alanine aminotransferase (important in liver due to producing pyruvate as the a- keto acid)

Aspartate aminotransferase (prod oxaloacetate = compound in TCA cycle)

Question 7

What can an increase in the circulating level of Alanine aminotransferase and Aspartate aminotransferase indicate?

Answer 7

That the body has ⬆️ the use of aa for energy (not normal).

This ⬆️ in aa degradation might indicate trauma or liver disease

Question 8

What is the difference between the deamination + transamination reaction?

Answer 8

Removal + elimination of end group in deamination reaction. – NH4+

– Taking place mostly in liver but can also happen in muscle when exercising at high intensity

Question 9

EQUATION for step 1 of the urea cycle

Answer 9

NH4+ + HCO-3 + 2ATP – (carbamoyl P synthetase) –> Carbamoyl P + 2ADP + Pi

Question 10

Which part of the urea cycle step 1 continues in the urea cycle for further processing?

Answer 10

Carbamoyl phosphate

Question 11

Step 2 of the urea cycle

Answer 11

Carbamoyl P enters Urea cycle by combining w/ ornithine to prod. citrulline.

Urea cycle:

Citrulline –> Argininosuccinate –> Arginine + fumerate (fumarate leaves cycle) –> Ornithine

Question 12

What aids the conversion reaction of citrulline –> argininosuccinate in the Urea/Ornithine cycle

Answer 12

Citrulline – ( Aspartate + ATP enter )(Aginiosuccinate synthetase) –> Argininosuccinate + AMP + PPi

Question 13

What aids the conversion reaction of argininosuccinate to arginine + fumarate in the Urea/Ornithine cycle

Answer 13

Argininiosuccinate lyase

Argininosuccinate – ( argininiosuccinate lyase) –> Arginine + fumarate

Question 14

What aids the conversion reaction of arginine to ornithine in the Urea/Ornithine cycle

Answer 14

Arginine – (H20 + arginase) –> urea + ornithine

Urea leaves cycle

Question 15

Why is the urea/ornithine cycle considered costly

Answer 15

Uses 4 ATP

• 2 in step 1
• 2: ATP –> AMP (instead of ADP)

Question 16

Elimination forms of excess nitrogen between aquatic animals, mammals + reptiles

Answer 16

Aquatic = Ammonia

Mammals = Urea

Many reptiles = Uric acid

Question 17

What is glutamine essential for?

Answer 17

Lymphocyte proliferation

Cytokin production

Macrophage phagocytosis

Question 18

What is the availability of glutamine compromised by in catabolic situations?

Answer 18

By the impaired balance between the release/uptake from bloodstream + key organs (gut, liver + skeletal muscle)

Question 19

List the BCAAs

Answer 19

Leucine

Isoleucine

Valine

(Essential aa)

Question 20

What can leucine stimulate

Answer 20

Protein synthesis - translation

Question 21

Where are the BCAAs mostly metabolised

Answer 21

In skeletal muscle

Less in liver

Question 22

Is the initial transamination of BCAAs reversible?

Answer 22

NO

Due to being essential aa

Question 23

What do ALL BCAAs produce?

Answer 23

Glutamate

Question 24

What can the glutamate produced from BCAAs be used for?

Answer 24

To produce alanine + a-ketoglutarate

Question 25

What does ACDH stand for

Answer 25

Acyl CoA dehydrogenase

Question 26

What are the enzymes for the steps of catabolising BCAAs

Answer 26

BCAAs share same enzymes for each of the 3 steps 1. BCAAT (Branched chain aa aminotransferase) 2. BCKAD (Branched chain keto acid dehydrogenase) 3. ACDH (Acyl CoA dehydrogenase)

Question 27

What are the options of end products from the breakdown of the BCAAs

Answer 27

Can either be: - Ketone body that can't be converted into glucose - Compound that can be converted into glucose

Question 28

aa metabolism during moderate intensity exercise

Answer 28

Mostly BCAAs used as energy (due to being an ⬆️ in the release of alanine from muscle telling us there's protein breakdown). Carbon skeletons of these then provide as intermediates of the TCA cycle. Also an ⬆️ in glutamate uptake from blood which depends on glycogen storage levels (starts at low or depleted glycogen)

Question 29

aa metabolism during high intensity exercise

Answer 29

Less glutamine prod to favour a-ketoglutarate. As contraction ⬆️ = prod of AMP + H+ ⬆️ -- leads to activation of adenylate deaminase which ⬆️ prod or conc of IMP + NH3

Question 30

What does IMP mean

Answer 30

Inosine monophosphate

Question 31

What is the particular metabolism happening at high intensity exercise?

Answer 31

Purine metabolism

Question 32

What is often used as a fatigue marker in muscles?

Answer 32

NH3