Biochemistry - Amino Acid Metabolism

Front 1

_________________ allow the degradation or synthesis of amino acids without generation of possibly toxic free ammonia

Back 1

aminotransferases

Front 2

Free ammonia can be scavenged by what two enzymes?

Back 2

glutamine synthetase and glutamate dehydrogenase

Front 3

Which enzyme has a low Km for ammonia?

Back 3

glutamine synthetase

Front 4

Where can amino acids be obtained from?

Back 4

- from the diet
- by protein degradation
- by de-novo synthesis (non-essential)

Front 5

Amino acid degradation involves...

Back 5

- the removal of the amino group
- eventual degradation of the carbon skeleton in the TCA cycle

Front 6

_____________ are specific for the respective a-amino acid and use mosly alpha-ketoglutarate as the alpha-keto acid

Back 6

aminotransferases

Front 7

Aminotransferases are specific for the respective alpha-amino acid and use mostly which alpha-keto acid?

Back 7

alpha-ketoglutarate

Front 8

Where is alanine aminotransferase (ALT) found in the liver?

Back 8

in they cytosol

Front 9

Where is aspartate aminotrasferase (AST) found in the liver?

Back 9

in both cytosol and mitochondria

Front 10

During liver damage, which enzymes increase in the blood and are considered injury markers for acute liver damage?

Back 10

aminotransferases

Front 11

Which enzyme catalyzes the conversion of glutamine to glutamate?

Back 11

glutaminase

Front 12

_________ glutaminase is used to form free ammonia for acid-base balance

Back 12

Renal

Front 13

__________ glutaminase uses glutamine from the diet or from the blood for energy metabolism in intestinal mucosal cells

Back 13

Intestinal

Front 14

Which enzyme catalyzes teh conversion of asparagine to aspartate?

Back 14

asparaginase

Front 15

Which enzyme is needed in rapldly dividing leukemic cells in very high amount?

Back 15

asparagine

Front 16

What can be used during cancer treatment to degrade the amino acid needed by leukemic cells?

Back 16

Asparaginase (to degrade asparagine)

Front 17

What two substrates can aminotransferase act on to form alanine?

Back 17

pyruvate and glutamate

Front 18

What two substrates can aminotransferase act on to form aspartate?

Back 18

oxaloacetate and glutamate

Front 19

What two substrates can aminotransferase act on to form glutamate?

Back 19

alpha-ketoglutarate and amino acid X

Front 20

Free ammonia can be used to synthesize glutamate from what?

Back 20

alpha-ketoglutarate

Front 21

Free ammonia can be used to synthesize glutamine from what?

Back 21

glutamate

Front 22

Glutamine can be used to form asparagine from what?

Back 22

aspartate

Front 23

Transaminases need what as a cofactor?

Back 23

PLP (Vit B6)

Front 24

At low ammonia concentrations, ammonia is immediately used by which enzyme?

Back 24

glutamine synthetase

Front 25

Why is glutamine and not free ammonia normally found in the cell?

Back 25

Because free ammonia is immediately taken up by glutamine synthetase

Front 26

______________ has a large Km form ammonia and can act at high ammonia conncentrations.

Back 26

Glutamate dehydrogenase

Front 27

High levels of which amino acid is toxic for the brain and can lead to edema?

Back 27

glutamine

Front 28

Depletion of which amino acid impairs neurotransmission?

Back 28

glutamate

Front 29

Patients with PKU need what type of diet?

Back 29

Low in phenylalanine and enriched with tyrosine. Mental retardation can be prevented when the diet starts shortly after birth.

Front 30

Patients with alkaptonuria and tyrosinosis need what type of diet?

Back 30

Low in both phenylalanine and tyrosine

Front 31

Patients with MSUD (Maple Syrup Urine Disease) need what type of diet?

Back 31

Low in branched-chain amino acid.

Front 32

Which amino acids are purely ketogenic?

Back 32

leucine and lysine

Front 33

Which amino acids are both glucogenic and ketogenic?

Back 33

(aromatic) phenylalanine, tyrosine, tryptophan, (branched) isoleucine

Front 34

Which amino acids can be degraded to succinyl CoA?

Back 34

valine, isoleucine, threonine, methionine (VIT M)

Front 35

Which amino acids can be degraded to fumarate?

Back 35

phenylalanine and tyrosine

Front 36

Which amino acids can be degraded to glutamate?

Back 36

arginine, histidine, proline

Front 37

Which amino acids can be degraded to acetoacetate?

Back 37

leucine, lysine, phenylalanine, tryptophan, tyrosine

Front 38

Which amino acids can be degraded to pyruvate?

Back 38

alanine, cysteine, glycine, serine, threonine, tryptophan

Front 39

Histidase deficiency

Back 39

Amino acid - histidine
Medical problem - mental retardation

Front 40

Methylmalonyl-CoA mutase deficiency

Back 40

Amino acids - met, thr, val, ile
Medical problem - metabolic acidosis

Front 41

Homocystinuria

Back 41

Amino acids - methionine
Medical problem - cardiovascular

Front 42

Maple-Syrup Urine Disease

Back 42

Amino acids - val, ile, leu (branched)
Medical problem - mental retardation

Front 43

Phenylketonuria PKU (Hyperphenylalaninemia)

Back 43

Amino acid - phenylalanine
Medical problem - mental retardation

Front 44

Alkaptonuria

Back 44

Amino acids - phe, tyr
Medical problem - crippling arthritis

Front 45

Tyrosinosis

Back 45

Amino acids - phe, tyr
Medical problem - liver cancer

Front 46

Methylmalonyl-CoA Mutase forms what molecule?

Back 46

succinyl CoA which can then join the TCA cycle

Front 47

Methymalony-CoA mutase needs what cofactor?

Back 47

Vitamin B12, cobalamin

Front 48

Homocystinuria is found in patients with what kind of deficiency?

Back 48

Genetic systathionine synthase deficiency. This can lead to severe and often fatal cardiovascular disease, mental retardation, and osteoporosis. Characteristic dislocation of the lens

Front 49

Characteristic dislocation of the lens is found in what disease?

Back 49

Homocystinuria

Front 50

Phenylalanine degradation starts with what?

Back 50

Hydroxylation to tyrosine (phenylalanine hydroxylase) which then will be transaminated

Front 51

How does the urine smell in PKU patients?

Back 51

musty

Front 52

Tyrosine is needed for the synthesis of what?

Back 52

catecholamines, thyroid hormones, melanin

Front 53

What test is performed to test for PKU?

Back 53

Guthrie test. Uses bacteria which need Phe for their growth.

Front 54

What can result from genetic defects in the degradation of both phenylalanine and tyrosine?

Back 54

Alkaptonuria and Tyrosinosis (Tyrosinemia I)

Front 55

If a patient's urine smells of boiled cabbage, what does the patient likely have?

Back 55

tyrosinosis

Front 56

Black urine can indicate what?

Back 56

Alkaptonuria. Homogentisate accumulates in urine and forms polymers that lead to black urine