2.10 Amino Acid Breakdown

Question 0

What enzyme catalyzes the first reaction in amino acid breakdown

Answer 0

Aminotransferases

Question 1

What is the first step in amino acid breakdown

Answer 1

Removal of alpha amino group

Question 2

Name the two important aminotransferases involved in the first step of AA degradtion

Answer 2

Alanine aminotransferase

Aspartate aminotransferase

Question 3

What is the function of Alanine Aminotransferase

Answer 3

an amino group from alanine is given to alpha ketoglutarate to form pyruvate and glutamate

Question 4

Function of Aspartate aminotransferase

Answer 4

Oxaloacetate recieves amino group from glutamate to produce aspartate and alpha-ketoglutarate.
This is the exception to the rule that glutamate receives an amino

Question 5

What is the coenzyme of the aminotransferase reaction?

Answer 5

Pyridoxal Phosphate - B6

Question 6

What happens to the remainder of the AA skeleton after degradation?

Answer 6

Carbon skeletons of alpha-ketoacids are used as intermediates in energy-producing metabolic pathway

Question 7

What is the relationship between pyruvate and alanine

Answer 7

Alanine becomes pyruvate after it releases one of its amino groups

Question 8

What is the relationship of alpha-ketoglutarate and glutamate

Answer 8

Alpha-ketoglutarate becomes glutamate when it gains an amino group

Question 9

What is the relationship between oxaloacetate and Aspartate?

Answer 9

Oxaloacetate gains an amino group and becomes Aspartate

Question 10

What is oxidative deamination and what amino acid undergoes this process?

Answer 10

Results in liberation of an amino group as a free ammonia

Glutamate is only amino acid to do this

Question 11

What enzyme catalyzes oxidative deamination

Answer 11

Glutamate Dehydrogenase

Question 12

Where is oxidative deamination found?

Answer 12

In Mitochondria of Liver and Kidney

Question 13

What are the allosteric inhibitors of Oxidative deamination

Answer 13

ATP and GTP

Question 14

What is the key reaction of the Urea Cycle and where does it occur?

Answer 14

HCO3, 2 ATP and Ammonium (from glutamate) –> Carbamoyl Phosphate
Occurs in mitochondrial matrix

Question 15

What enzyme catalyzes the key reaction of the urea cycle

Answer 15

Carbamoyl Phosphate Synthetase I (CPS1)

Question 16

What does Carbamoyl Phosphate Synthetase I require for activity

Answer 16

N-Acetyl Glutamate

Question 17

Where does the Urea Cycle occur?

Answer 17

Liver mitochondria and cytosol

Question 18

Where do the nitrogens in the urea cycle come from?

Answer 18

Ammonia comes from Glutamate and Aspartate

Question 19

What is the ATP expense in the Urea Cycle

Answer 19

4 High energy phosphate bonds are broke

Question 20

Where is Glutamine found in high concentrations?

Answer 20

Plasma

Question 21

What enzyme catalyzes Glutamine giving its ammonia to become Glutamate in the liver

Answer 21

Glutaminase

Question 22

Alanine is used to transport ammonia from where?

Answer 22

From muscle to liver.

Question 23

Alanine travels to liver to react with what to form what?

Answer 23

It reacts with alpha-ketoglutarate to form Glutamate and Pyruvate

Question 24

Describe how Aspartate adds its ammonium group to the urea cycle

Answer 24

It combines with Citrulline with the help of Argininosuccinate Synthase. This produces Argininosuccinate

Question 25

How is Fumarate formed and why is it significant?

Answer 25

Argininosuccinate is cleaved to yield Arginine and Fumarate. Fumarate enters the CAC and links the two cycles together

Question 26

Describe how fumarate and aspartate link the urea cycle to the CAC

Answer 26

Aspartate gives an ammonium molecule to Citrulline to make Argininosuccinate.
Argininosuccinate is cleaved to yield Arginine and Fumarate. Fumarate enters CAC and is oxidized to Oxaloacetate.
Oxaloacetate is then turned into Aspartate when given an Ammonium group

Question 27

What causes Ammonia Toxicity?

Answer 27

A shift in Glutamate dehydrogenase towards Glutamate depletes alpha-ketoglutarate which causes toxicity

Question 28

Describe the reaction and enzyme that is used to finally produce Urea

Answer 28

Arginine –> Ornthinine + Urea

Enzyme: Arginase