Class 4: Amino Acid Metabolism

Question 1

What does amino acid output

Answer 1

• glucose + glycogen
• CO2 + H2O
• ketone bodies, fatty acids, steroids

Question 2

2 ways Amino Acids Degrade

Answer 2

1) removal of the @-amino groups (nitrogen) by transamination and oxidative deamination

2) carbon skeletons of the @-ketoacids are converted to common intermediates of energy-producing, metabolic pathway

Question 3

what’s the first step of degradation of amino acids

Answer 3

removing nitrogen

Question 4

transamination

Answer 4

The transfer of the a-amino group of an amino acid to a-Keto acid

The end products: a-Keto acid and amino acid

enzyme: amino transferase

Question 5

What is ALT transamination

Answer 5

alanine –> pyruvate
- predominantly in the liver, a more specific indicator of liver damage. (American Red Cross, hepatitis C)

Question 6

what is AST transamination

Answer 6

aspartate –> oxaloacetate
- in the liver, heart (cardiac muscle), skeletal muscle, kidneys, brain, and red blood cells, damage to liver, muscle (creatine kinase), brain.

Question 7

Oxidative Deamination
Place:
Enzyme:
Activators:
Inhibitors:
Coenzymes:

Answer 7

Place: liver and kidney
Enzyme: Glutamate dehydrogenase
Activators: ADP and GDP
Inhibitors: ATP and GTP (negative feedback regulation)
Coenzyme: NAD+ or NADP+

Question 7

Oxidative Deamination
Place:
Enzyme:
Activators:
Inhibitors:
Coenzymes:

Answer 7

Place: liver and kidney
Enzyme: Glutamate dehydrogenase
Activators: ADP and GDP
Inhibitors: ATP and GTP (negative feedback regulation)
Coenzyme: NAD+ or NADP+

Question 8

3 ways to transport and release ammonia

Answer 8

Transport:
a) As glutamine (to liver or kidney)
b) As alanine (to liver from muscle)
c) As urea (to kidney from liver)

Release:
- Urea (90%)
- ammonia ion (3%)

Question 9

Urea cycle

Answer 9

aspartate + ammonium ( 2 nitrogen’s) –> 2 amines, neutral, non polar

1) The major disposal form of amino groups derived from amino acids
2) 90% of the nitrogen-containing components of urine

Question 10

Where is the place of production and excretion of the urea cycle

Answer 10

Liver and Kidney

Question 11

5 steps of Urea Cycle

Answer 11

1) Formation of carbamoyl phosphate (2 ATP)
2) Formation of citulline
3) Formation of Arginosuccinate
4) Cleavage of Argininosuccinate
5) Cleavage of arginine to ornithine and urea

Question 11

5 steps of Urea Cycle

Answer 11

1) Formation of carbamoyl phosphate (2 ATP)
2) Formation of citulline
3) Formation of Arginosuccinate
4) Cleavage of Argininosuccinate
5) Cleavage of arginine to ornithine and urea

Question 12

why is urea an irreversible process

Answer 12

4 high energy phosphates are consumed

Question 13

find out more about the blood urea nitrogen test

Answer 13

BUN

Question 14

what r the 2 fates of the carbo skeletons of amino acids

Answer 14

1) Amino Acids whose catabolism yields pyruvate or one of the intermediates of the TCA cycle can produce glucose - glucogenic

2) Amino Acids whose catabolism yields either acetoacetate or
acetyl CoA or acetoacetyl CoA - ketogenic

Question 15

what amino acids form pyruvate

Answer 15

• serine
• cysteine
• alanine
• glycine
• threonine
• tryptophan

Question 16

what is a FIGLU test:

Answer 16

a urine test, an indicator of Vitamin B12 or folic acid deficiency or liver disease

FIGLU: N-Formiminoglutamate

Question 16

what is a FIGLU test:

Answer 16

a urine test, an indicator of Vitamin B12 or folic acid deficiency or liver disease

FIGLU: N-Formiminoglutamate

Question 17

what amino acids form fumarate

Answer 17

phenylalanine
tyrosine

Question 18

what is PKU

Answer 18

• deficiency of phylalanine hydroxylase
• Hyperphenylalaninemia
• Defect in the conversion of Phenylalanine to Tyrosine

Question 19

wha is “mousy”

Answer 19

odor in urine

Question 20

CNS Symptoms

Answer 20

-Cognitive disability or intellectual disability
-Cerebral and basal ganglion dysfunction)
-failure to walk or talk
-seizure and failure to grow

Question 21

CNS potential causes

Answer 21

1) lack of the tyrosine, precursor of catecholamines (norepinephrine)

2) toxic effect of high levels of phenylalanine in the brain, blocking the transport or metabolism of other aromatic amino acids (e.g., tyrosine, tryptophan)

3) Inhibit the synthesis of other substances required for brain growth (Microcephaly)

4) Hypopigmentation: fair hair, light skin color and blue eyes, no melanin (Albinism)

Question 22

CNS treatment

Answer 22

diet with very low amount of phenylalanine

Question 23

what is S-adenosylmethione (SAM)

Answer 23

the major methyl-group donor in one carbon metabolism

Question 24

what are the two major disposal pathways of homocysteine

Answer 24

1) synthesis of cysteine
- formation of cysteine requires vitamin B6 (PLP)

2) Resynthesis of methionine

Question 25

what are the two reactions using vitamin B12

Answer 25

1) L-homocysteine –> L-Methionine

2) L-methylmalonyl –> succinyl CoA

Question 26

essential amino acids

Answer 26

amino acids that cannot be synthesized de novo by the body and must be obtained from the diet in order for normal protein
synthesis to occur.

Question 27

nonessential amino acids

Answer 27

amino acids that can be synthesized in sufficient amounts from the intermediates of metabolism or, from essential amino acids.

Question 27

nonessential amino acids

Answer 27

amino acids that can be synthesized in sufficient amounts from the intermediates of metabolism or, from essential amino acids.

Question 28

conditional amino acids

Answer 28

This means they’re only considered essential when you’re ill or stressed. Conditional amino acids include arginine, cysteine, glutamine, tyrosine, glycine, ornithine, proline and serine.

Question 29

ammonia fixation

Answer 29

The use of ammonia in the net synthesis of nitrogen-containing molecules