Lecture 32 - Amino Acid Syntheis

Question 1

What precursor molecules from what what pathways are used in amino acid synthesis? (7)

L32 S5

Answer 1

Glycolysis:

• 3-phosphoglycerate
• phosphoenolpyruvate
• pyruvate

TCA cycle

• α-ketoglutarate
• oxaloacetate

Pentose phosphate pathway:

• ribose-5-phosphate
• erythrose-5-phosphate

Question 2

What are the transamination reactions and what amino acids do they synthesize?

L32 S8

Answer 2

Serum glutamate-oxaloaceate transaminase/AST:
-generates aspartate from oxaloacetate

Serum glutamate-pyruvate tranaminase/ALT:
-generates alanine from pyruvate

Glutamate dehydrogenase:
-generates glutamate from α-ketoglutarate

Question 3

How do lysine, threonine, and methionine affect aspartate conversion?

L32 S10

Answer 3

All of these are derived from aspartate and inhibit conversion of aspartate to these AAs.

Question 4

How is glutamine synthesis regulated?

L32 S12

Answer 4

Adenylylated glutamine synthetase is in activated.

Pii is what adenylylates glutamine synthetase

Uridylylation of Pii causes it to deadenylylate glutamine synthetase (activation) and deuridylylation causes it to adenylylate glutamine synthetase (inactivation)

Question 5

What is the precursor of alanine?

L32 S8

Answer 5

pyruvate -> alanine

Question 6

What is the precursor of aspartate?

L32 S8

Answer 6

oxaloacetate -> aspartate

Question 7

What is the precursor of glutamate?

L32 S8

Answer 7

α-ketoglutarate -> glutamate

Question 8

What is the precursor of asparagine?

L32 S9

Answer 8

oxaloacetate -> aspartate -> asparagine

Question 9

What is the precursor of glutamine?

L32 S11

Answer 9

α-ketoglutarate -> glutamate -> glutamine

Question 15

What is the precursor of histidine?

L32 S18

Answer 15

ribose-5-phosphate -> histidine

Question 16

What are the precursors of tryptophan, phenylalanine, and tyrosine?

L32 S18

Answer 16

erythrose-4-phosphate + phosphoenolpyruvate -> [X]

Question 17

What are the branched amino acids and what is their precursor?

What is the common function of these amino acids?

L32 S19

Answer 17

Valine, leucine, and isoleucine

All derive from pyruvate

All are solely used for protein synthesis

Question 18

What amino acid is heme a derivative of?

L32 S22

Answer 18

Glycine + acetate

Question 19

What molecules are derived from glutamate? (3)

L32 S25

Answer 19

Glutathione:
-antioxidant

Putrescine (polyamines):
-stabilizes DNA

GABA:
-inhibitory neurotransmittter

Question 20

What molecules are derived from arginine?

L32 S26

Answer 20

NO

Creatine

Question 21

What molecules are derived from methionine?

L32 S27

Answer 21

S-adenosylmethionine (SAM):

-primary methyl donor

Question 22

What molecules are derived from histidine?

L32 S28

Answer 22

Histamine

Question 23

What molecules are derived from tryptophan?

L32 S29

Answer 23

Serotonin

Question 24

What molecules are derived from tyrosine?

L32 S30

Answer 24

Epinephrine

Norepinephrine

Dopamine

Melanin

Question 25

What is the precursor of proline?

L32 S13

Answer 25

α-ketoglutarate -> glutamate -> proline

Question 26

What is the precursor of serine?

L32 S14

Answer 26

3-phosphoglycerate -> serine

Question 27

What is the precursor of glycine?

L32 S15

Answer 27

3-phosphoglycerate -> serine -> glycine

Question 28

What is the precursor of cysteine?

L32 S16

Answer 28

3-phosphoglycerate -> serine -> cysteine

Question 29

What is the precursor of tyrosine?

L32 S17

Answer 29

phenylalanine -> tyrosine