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Flashcards in studystack 2 Deck (221)
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1

Amino acid catabolism produces what toxic product?

Ammonia

2

When does negative nitrogen balance occur?

Dietary Deficiency (starvation)
Catabolic stress (ex. infection)

3

What 3 cofactors are required for amino acid synthesis?

Pyridoxal phosphate Tetrahydrofolate Tetrahydrobiopterin (BH4)

4

When pyruvate is transaminated, what does it synthesize?

Alanine

5

When oxaloacetate is transaminated, what does it synthesize?

Aspartate

6

When alpha-ketoglutarate is transaminated, what does it synthesize?

Glutamate

7

What forms alanine by transamination?

Pyruvate

8

What forms aspartate by transamination?

Oxaloacetate

9

What forms glutamate by transamination?

alpha-ketoglutarate

10

Where is arginine generated?

Urea cycle

11

Where does Cysteine get its S?

Methionine

12

What is pyridoxal phosphate (PLP) synthesized from?

Vitamin B6

13

What are two mechanisms through which nitrogen is removed from amino acids?

Transamination
Deamination

14

What enzyme is involved in the oxaloacetate --> aspartate reaction?

AST

15

What is the function of glutamate dehydrogenase?

It deaminates glutamate, resulting in alpha-ketoglutarate and ammonia.

16

Where does the deamination of glutamate by glutamate dehydrogenase take place?

Liver

17

What enzyme is involved in the deamination of glutamate into alpha-ketoglutarate and ammonia?

Glutamate dehydrogenase

18

What enzyme is involved in the conversion of glutamate + ammonium (NH4+) --> glutamine

Glutamine synthase

19

What conversion does glutamine synthase catalyze?

glutamate and ammonium --> glutamine

20

What enzyme is involved in the conversion:glutamine --> glutamate + NH4+?

Glutaminase

21

In the FASTED state, what do the liver and muscles contribute to amino acid metabolism?

Muscles = provide amino acids for metabolismLiver = uses lots of amino acids in fasted state.

22

Where does the urea cycle occur?

Liver

23

What is the enzyme that converts HCO3- + NH4+ --> Carbamoyl phosphate?

CPS1 (carbamoyl phosphate synthase 1)

24

What is the rate limiting step in the urea cycle?

CPS1 (carbamoyl phosphate synthase 1)

25

What is the enzyme that converts Ornithine to Citrulline?

OTC (ornithine transcarbomylase)

26

What is the common source of both of the N's in urea?

Glutamate

27

Where do the first two steps of the urea cycle occur?

Mitochondria

28

In the urea cycle, after the first two steps, where do the following steps occur?

Cytoplasm

29

What are two products from the urea cycle?

Arginine fumarate

30

What is the role of NAG in the urea cycle?

It is synthesized by acetyl CoA and glutamate and it STIMULATES CPS1