Block 2 Lecture 4 -- Amino Acid Synthesis

Question 1

What are the essential amino acids?

Answer 1

1) Phe
2) Val
3) Thr
4) Try
5) Ile
6) Met
7) His
8) Arg
9) Leu
10) Lys

Question 2

Which amino acids are synthesized from glycolysis intermediates?

Answer 2

1) Ser
2) Gly
3) Cys
4) Ala

Question 3

What amino acids are synthesized from TCA intermediates?

Answer 3

1) Arg
2) Asp
3) Asn
4) Glu
5) Gln
6) Pro

Question 4

What amino acids do not have transamination pairs?

Answer 4

1) Lys
2) Pro
3) Thr

Question 5

Which non-essential amino acid is not derived from glycolysis/TCA?

Answer 5

Tyr (from the essential Phe)

Question 6

What is the TA pair for Glu?

Answer 6

a-KG

Question 7

What is the TA pair for Asp?

Answer 7

OAA

Question 8

What is the TA pair for Ala?

Answer 8

Pyruvate

Question 9

What is the TA pair for Gly?

Answer 9

glyoxylate

Question 10

What is the TA pair for ornithine?

Answer 10

Glu-5-Semialdehyde

Question 11

How can serine be synthesized?

Answer 11

1) 3-phosphoserine phosphatase – from 3-PG, direct product of glucose via 3-PGDH
2) serine hydroxymethyltransferase – from glycine (THF)

Question 12

What compounds can serine synthesize?

Answer 12

1) serine dehydratase = pyruvate
2) + homocysteine –> cystathionine –> cysteine
3) serine hydroxymethyltransferase = glycine via THF

Question 13

how is serine synthesis induced?

Answer 13

1) 3-PGDH induction

2) release of phosphoserine phosophatase feedback inhibition

Question 14

How is glycine synthesized?

Answer 14

1) Serine hydroxymethyltransferase

2) Thr aldolase

Question 15

How is glycine degraded?

Answer 15

1) GCC donates carbon to FH4, produces CO2 + NH4
2) D-amino-oxidase oxidizes to glyoxylate
3) TA to glyoxylate with Ala/pyruvate

Question 16

What is the cofactor in GCC?

Answer 16

NAD & FH4

Question 17

What is the cofactor in Thr aldolase?

Answer 17

PLP

Question 18

How is cysteine synthesized?

Answer 18

1) cystathionine synthase then cystathionase

Question 19

What reactions does cysteine do?

Answer 19

1) desulfhydrase
- - donates NH3 to Glu
- - carbons become pyruvate
- - sulfate to urine

Question 20

What is the cofactor in cystathionine synthase?

Answer 20

PLP

Question 21

What reaction does cystathionine synthase catalyze?

Answer 21

Ser + Homocysteine –> Cystathionine

Question 22

What is the cofactor in the cystathionase reaction?

Answer 22

PLP

Question 23

What reaction does cystathionase catalyze?

Answer 23

Cystathionine + H2O –> a-KB + cysteine + NH4

Question 24

How is alanine produced?

Answer 24

transamination with pyruvate – especially in muscle

Question 25

How is Glu produced?

Answer 25

1) TA with a-KG
2) from Gln (Glutaminase)
3) from FIGLU (His & THF)

Question 26

What reactions does Glu take part in?

Answer 26

1) Gln synthase
2) TA
3) Glu DH (urea cycle)
4) reductase & phosphorylation –> Glu-5-SA

Question 27

How is Pro synthesized?

Answer 27

1) spontaneous cyclization of G5SA

2) reduction (FAD/NAD)

Question 28

What is the co-factor in GluDH?

Answer 28

NAD

Question 29

How is glyoxylate degraded?

Answer 29

1) oxidized to oxalate
…or….
2) to a-KG with TPP as cofactor

Question 30

What functional group is produced when G5SA cyclizes?

Answer 30

Schiff base/imine

Question 31

Where does proline synthesis occur in the cell?

Answer 31

1) Glu phosphorylation –> G5SA in mitochondria

2) G5SA reduced to Pro in cytosol

Question 32

How is arginine produced?

Answer 32

1) G5SH TA to ornithine, enters urea cycle

2) Arginase produces Arg

Question 33

Where does TA occur with G5SH?

Answer 33

• *on the side chain

- - an oddity

Question 34

What happens when ornithine is in excess?

Answer 34

G5SA increases

Glu increases

Question 35

What amino acids are synthesized form G5SA

Answer 35

Proline & Arginine

Question 36

What is a sign of folate deficiency related to His metabolism?

Answer 36

FIGLU would be found in urine

Question 37

How is aspartate synthesized?

Answer 37

1) TA with OAA (PLP)

2) Asn-ase (hydrolytic non-oxidative deamination)

Question 38

How is Asn synthesized?

Answer 38

1) Asn synthetase (requires ATP & Gln)

Question 39

What cofactors does Asn synthetase require?

Answer 39

1) ATP

2) Gln –> Glu