Amino Acid Metabolism

Question 1

What is a major difference between glucogenic and ketogenic aa breakdown?

Answer 1

Glucogenic – can contribute to blood glucose levels

Ketogenic – can’t contribute to blood glucose levels

Question 2

What are the two amino acids that can only undergo ketogenic breakdown?

Answer 2

Leu

Lys

Question 3

What amino acids can undergo glucogenic and ketogenic breakdown?

Answer 3

ile
thr
phe
tyr
trp

Question 4

What vitamin is a major cofactor in aa metabolism?

Answer 4

Pyridoxal phosphate (PLP)
B6

Question 5

AA carbons are converted to intermediates of what three central pathways?

Answer 5

Glycolytic pathways
TCA cycle
Lipid metabolism

Question 6

What is the first step of amino acid metabolism?

Answer 6

transfer of the alpha-amino group via transamination

Question 7

What is the amino acid that can’t undergo transamination?

Answer 7

lys

Question 8

Some leukemic cells have low asparagine synthetase activity and require exogenous asparagine. _________ is used to reduce serum asparagine and clinically to treat acute lymphoblastic leukemia

Answer 8

Asparaginase

Question 9

What three amino acids enter metabolism glucogenically as pyruvate, directly? They are the 3 carbon amino acids

Answer 9

Ala
Ser
Cys

Question 10

If you are lacking what enzyme, will you possibly develop kindey stones from glyoxylate?

Answer 10

glyoxylate transamiase (oxaluria type 1)

Question 11

Serine, Cysteine, and glycine are formed from ________

Answer 11

3-phophoglycerate

Question 12

What are the 3 reactions in the transformation of 3-phosphoglycerate to serine?

Answer 12

Oxidation
Transamination
Hydrolysis

Question 13

Cysteine is synthesiszed from _______ and _________

Answer 13

serine and homocysteine

Question 14

Defects in what enzyme can cuase elevated homocysteine? (Homocystinuria)

Answer 14

cystathionine beta-synthase

Question 15

What is one way to treat homocystinuria?

Answer 15

With Pyridoxal Phosphate

Question 16

Methionine synthase requires what vitamin as a cofactor?

Answer 16

Vitamin B12

Question 17

Skeletal muscle is high in what type of amino acids?

Answer 17

branched-chain

val, ile, leu

Question 18

Catabolism for what three amino acids starts in skeletal muscle not the liver?

Answer 18

val, ile, leu

branched chain aa

Question 19

1 mol of a BCAA yields how much ATP?

Answer 19

101 moles

Question 20

What enzyme is found in high concentrations in skeletal muscle and is used to make ATP from BCAAs?

Answer 20

BCAA Transaminase

Question 21

What do transaminases depend on as a cofactor?

Answer 21

B6 = PLP

Question 22

What is Maple syrup urine disease (MSUD)?

Answer 22

A genetic defect in BCKA dehydrogenase
High BCAAs (val, leu, ile) and alpha-ketoacids in urine and plasma

Question 23

What are the two B12 dependent reactions in humans?

Answer 23

Methylmalonyl-CoA Mutase

Methionine synthase

Question 24

Phenylalanine is converted to what amino acid during its metabolism?

Answer 24

Tyrosine