2.10 Amino Acid Breakdown Flashcards Preview

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Flashcards in 2.10 Amino Acid Breakdown Deck (29):
0

What is the first step in amino acid breakdown

Removal of alpha amino group

1

What enzyme catalyzes the first reaction in amino acid breakdown

Aminotransferases

2

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

Alanine aminotransferase
Aspartate aminotransferase

3

What is the function of Alanine Aminotransferase

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

4

Function of Aspartate aminotransferase

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

5

What is the coenzyme of the aminotransferase reaction?

Pyridoxal Phosphate - B6

6

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

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

7

What is the relationship between pyruvate and alanine

Alanine becomes pyruvate after it releases one of its amino groups

8

What is the relationship of alpha-ketoglutarate and glutamate

Alpha-ketoglutarate becomes glutamate when it gains an amino group

9

What is the relationship between oxaloacetate and Aspartate?

Oxaloacetate gains an amino group and becomes Aspartate

10

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

Results in liberation of an amino group as a free ammonia
Glutamate is only amino acid to do this

11

What enzyme catalyzes oxidative deamination

Glutamate Dehydrogenase

12

Where is oxidative deamination found?

In Mitochondria of Liver and Kidney

13

What are the allosteric inhibitors of Oxidative deamination

ATP and GTP

14

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

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

15

What enzyme catalyzes the key reaction of the urea cycle

Carbamoyl Phosphate Synthetase I (CPS1)

16

What does Carbamoyl Phosphate Synthetase I require for activity

N-Acetyl Glutamate

17

Where does the Urea Cycle occur?

Liver mitochondria and cytosol

18

Where do the nitrogens in the urea cycle come from?

Ammonia comes from Glutamate and Aspartate

19

What is the ATP expense in the Urea Cycle

4 High energy phosphate bonds are broke

20

Where is Glutamine found in high concentrations?

Plasma

21

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

Glutaminase

22

Alanine is used to transport ammonia from where?

From muscle to liver.

23

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

It reacts with alpha-ketoglutarate to form Glutamate and Pyruvate

24

Describe how Aspartate adds its ammonium group to the urea cycle

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

25

How is Fumarate formed and why is it significant?

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

26

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

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

27

What causes Ammonia Toxicity?

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

28

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

Arginine --> Ornthinine + Urea
Enzyme: Arginase