amino acid synthesis

Question 1

OAA can be synthesized from what 2 amino acids directly?

Answer 1

aspartate and asparagine

Question 2

Pyruvate can be synthesized by what 3 amino acids?

Answer 2

alanine
serine (from glycine)
cysteine

Question 3

What enzyme catalyzes asparagine to aspartate?

Answer 3

Asparaginase, transfer of NH4+

Question 4

What enzyme catalyzes aspartate to OAA?

Answer 4

AST (alanine aminotransferase), requires co-factor PLP

Question 5

What enzyme catalyzes glutamine to glutamate?

Answer 5

glutaminase, transfer of NH4+

Question 6

What 3 amino acids can be used to synthesize glutamate?

Answer 6

proline, histidine, arginine

Question 7

What enzyme catalyzes aspartate to asparagine?

Answer 7

asparagine synthetase

Question 8

What enzyme catalyzes aspartate to OAA?

Answer 8

AST (aspartate aminotransferase)

Question 9

What enzyme catalyzes serine to glycine (reversible)?

Answer 9

serine hydroxymethyl transferase, requires co-factor PLP

Question 10

All aminotransferases require what co-factor?

Answer 10

Vitamin B6, PLP (pyridoxal 5’-phosphate)

Question 11

Synthesis of serine starts with what as substrate?

Answer 11

3-phosphoglycerate (from glycolysis)

Question 12

What molecule serves as amino group donor for keto-acid?

Answer 12

glutamate

Question 13

What molecule serves as amino group acceptor for the corresponding amino acid?

Answer 13

alpha-ketoglutarate

Question 14

phosphoglycerate dehydrogenase
3-phosphoserine aminotransferase
phophatase

Answer 14

enzymes involved in the synthesis of serine

Question 15

What are the essential amino acids?

Answer 15

PVT TIM HALL
Phe
Val
Thr
Trp
Iso
Met
His
Arg
Leu
Lys

Question 16

What is generated by transamination of alpha-ketoglutarate and by deamidation of glutamine.

Answer 16

glutamate

Question 17

Tyrosine is formed from what amino acid and by what enzyme? What co-factor is needed?

Answer 17

phenylalanine, phenylalanine hydroxylase, co-factor THBtn

Question 18

What is formed from serine and the essential amino acid methionine?

Answer 18

cysteine

Question 19

What is the major source of one-carbon groups in the one carbon pool?

Answer 19

serine

Question 20

Describe the synthesis of methionine from homocysteine. Why is this reaction important?

Answer 20

homocysteine + N5-methyl-THF&raquo_space; methionine + THF

Enzyme: methionine synthase
Co-factor: B12
**only reaction that converts the most reduced form of THF (N5-methyl-THF) back to THF

Question 21

Describe the synthesis of cysteine from homocysteine.

Answer 21

1) homocysteine + serine>>cystathionine
Enzyme: cystathionine beta-synthase
Co-factor: PLP (Vit. B6)
2) cystathionine>>cysteine
Enzyme: cystathionase

Question 22

Where are branched-chain aminotransferases located?

Answer 22

skeletal muscles

Question 23

What are the three branched-chain amino acids (BCAAs)?

Answer 23

Valine, Isoleucine, Leucine

Question 24

What is the function of branched-chain aminotransferases?

Answer 24

convert BCAAs to their corresponding branched-chain keto-acids

Question 25

branched chain alpha-ketoacids are decarboxylated by what in the liver and other tissues?

Answer 25

branched-chain alpha-ketoacid dehydrogenase complex (BCKDH)

Question 26

What products are produced by BCKDH?

Answer 26

branched chain acyl-CoAs

Question 27

What acyl-CoA does the catabolism of valine produce?

Answer 27

propionyl-CoA

Question 28

What acyl-CoA does the catabolism of isoleucine produce?

Answer 28

propionyl-CoA and acetyl-CoA

Question 29

What acyl-CoA does the catabolism of leucine produce?

Answer 29

acetyl-CoA