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Biochem > Amino acid metabolism 2 > Flashcards

Amino acid metabolism 2 Flashcards

1
Q

Histidine intermediate elevated in folate/B12 deficiencies

A

Formiminoglutamate (FIGLU)

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2
Q

Formiminoglutamate (FIGLU) is an intermediate in the breakdown of this amino acid to which other amino acid?

A

Histidine –> FIGLU –> Glutamate

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3
Q

Enzyme that catalyzes:
Asparagine –> Aspartate

A

Asparaginase

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4
Q

Neoplastic cells have low levels of this enzyme
Reason why L-asparaginase is antitumor agent

A

Asparagine synthetase

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5
Q

Enzyme that catalyzes:
Aspartate –> Aspargine

A

Asparagine synthetase

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6
Q

Aspartate can be converted to this TCA cycle substrate via transamination

A

Oxaloacetate

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7
Q

Tyrosine is a product of

A

Phenylalanine

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8
Q

Hemogentisic acid is a product of

A

Tyrosine

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9
Q

Homogentisic acid can be used to make this TCA cycle substrate

A

Fumarate

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10
Q

Homogentisic acid can be used to make this ketone body

A

Acetoacetate

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11
Q

Alpha-ketobutyrate can be used to make propionyl CoA along with this amino acid

A

Cysteine

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12
Q

Requirements for alpha-keto acid dehydrogenase (5)

A

TPP, riboflavin, lipoic acid, pantothenic acid, niacin

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13
Q

Enzyme deficient in Maple Syrup Urine Disease

A

Alpha-keto acid dehydrogenase

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14
Q

Branched chain amino acid levels are high in these organs

A

Muscle, brain, kidney

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15
Q

Branched chain amino acids levels are relatively low in this organ

A

Liver

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16
Q

3 branched chain amino acids

A

Leucine, Isoleucine, Valine

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17
Q

Oxidation of these supplies most of blood glutamine during fasted state

A

Branched chain amino acids

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18
Q

Oxidation of branched chain amino acids supplies most of the blood levels of this during fasted state

A

Glutamine

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19
Q

Strictly ketogenic amino acid, giving rise only to Acetyl CoA

A

Leucine

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20
Q

Immediate breakdown products from tryptophan

A

Kyneurenine and formate

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21
Q

Breakdown products of kynurenine (2)

A

Alanine and acetyl CoA

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22
Q

Niacin can be made from the breakdown of this amino acid

A

Tryptophan –> Kynurenine

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23
Q

Severe niacin deficiency
Skin, GI tract, CNS involvement
Dermatitis, Diarrhea, Dementia

A

Pellagra

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24
Q

Pellagra is a deficiency in this

A

Niacin

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25
Q

Niacin is this vitamin

A

B3

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26
Q

Vitamin B3 is this

A

Niacin

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27
Q

Large doses of this vitamin inhibits lipolysis in adipose tissue and VLDL and LDL synthesis
Used to treat hyperlipoproteinemia

A

Niacin

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28
Q

Isoleucine can form these 2 molecules

A

Acetyl coA and succinyl CoA

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29
Q

Amino acids that form Acetyl CoA (7)

A

Trp, Thr, Ile, Lys, Leu, Phe, Tyr

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30
Q

Enzyme that catalyzes:
Phe + BH4 → Tyr + BH2

A

Phenylalanine hydroxylase

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31
Q

Classical PKU involves a deficiency in this enzyme

A

Phenylalanine hydroxylase

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32
Q

Enzyme that catalyzes:
BH2 + NADH → BH4 + NAD+

A

Dihydropteridine reductase

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33
Q

Atypical PKU involves a deficiency of this enzyme

A

Dihydropteridine reductase

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34
Q

Amino acid that becomes essential in PKU

A

tyrosine

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35
Q

Large neutral amino acid transporter

A

LAT1

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36
Q

Large neutral amino acids (7)

A

Phe, Tyr, Trp, Leu, Lys, Ile, Arg

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37
Q

In PKU, Phe outcompetes other large neutral amino acids for this

A

LAT1 transport

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38
Q

Enzymes inhibited in PKU due to accumulation of phenylalanine

A

Tyr and Trp hydroxylase

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39
Q

3 unusual metabolites that are seen in PKU in blood and urine (require PLP)

A

Phenylpyruvate
Phenylacetate
Phenyllactate

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40
Q

Tyrosine is degraded to these 2 products

A

Fumarate and acetoacetate

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41
Q

Defective enzyme in alcaptonuria

A

Homogentisate oxidase

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42
Q

Intermediate breakdown product of tyrosine that is accumulated in alcaptonuria

A

Homogentisate

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43
Q

Alcaptonuria involves a defect in the breakdown of this amino acid

A

Tyrosine

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44
Q

Substance in alcoptonuria that is oxidized and polymerized to a melanin-like substance

A

Homogentisate

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45
Q

Serine can be formed from this glycolysis intermediate

A

3-phosphoglycerate

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46
Q

Amino acid that can form glycine

A

Serine

47
Q

The conversion of serine to glycine requires this

A

FH4

48
Q

The conversion of serine to glycine produces this

A

N5N10-Methylene FH4

49
Q

2 ways that serine can be converted to pyruvate

A

Serine –> 2-phosphoglycerate –> pyruvate
Serine –> cysteine –> pryuvate

50
Q

Enzyme that catalyzes:
Aspartate + Glutamine + ATP → Asparagine + Glutamate + AMP + PPi

A

Asparagine synthetase

51
Q

Enzyme that catalyzes:
Serine + FH4 → Glycine + 5,10-methylene-FH4

A

Ser-OH-methyl-transferase

52
Q

FH4 is derived from dietary vitamin folate by reduction with this enzyme

A

Dihydrofolate reductase

53
Q

Only amino acid metabolism path that is regulated

A

Cysteine metabolism

54
Q

Ca2+ oxalate kidney stones are formed from this reaction

A

Glycine –> Glyoxylate –> Oxalate

55
Q

Molecule that contributes the sulfur to cysteine

A

Methionine

56
Q

Conversion of methionine to homocysteine involves this intermediate

A

S-adenosyl-Met (SAM)

57
Q

Enzyme that catalyzes:
Homocysteine + Serine → Cystathionine

A

Cystathionine synthase

58
Q

Genetic defects in cystathionine synthase can be helped with macro doses of this

A

Vitamin B6

59
Q

Predominant mutation in cystathionine synthase results in this

A

Increased Km

60
Q

Molecule that contributes the carbon to cysteine

A

Serine

61
Q

Cysteine is formed from these 2 amino acids

A

Methionine and serine

62
Q

Enzyme that catalyzes:
Cystathionine → Alpha-ketobutyrate + Cysteine

A

Cystathionine lyase

63
Q

Alpha-ketobutyrate can form this

A

Propionyl CoA

64
Q

The conversion of cysteine to pyruvate forms this

A

Sulfite

65
Q

Sulfite formed from the conversion of cysteine to pyruvate can be converted to sulfate, and then this molecule

A

PAPs

66
Q

PAPs (formed from sulfate) can be used to do this

A

Sulfate GAGs

67
Q

conversion of this amino acid generates PAPs

A

Cysteine

68
Q

Compound that methylates precursor molecules
Involved in many important processes

A

S-Adenosyl-Met (SAM)

69
Q

Enzyme that catalyzes:
dUMP + N5,N10-methylene FH4 → dTMP + FH2

A

Thymidylate synthase

70
Q

4 amino acids that are sources of one carbon derivates of FH4

A

Serine, glycine, histidine, tryptophan

71
Q

Only reaction that uses N5-methyl-FH4

A

N5-methyl FH4 + Homocysteine → FH4 + Methionine

72
Q

Only 2 reactions that require Vitamin B12

A

Resynthesis of Methionine from homocysteine
Rearrangement of L-methylmalonyl CoA to form succinyl CoA

73
Q

Resynthesis of Methionine from homocysteine requires this vitamin

A

B12

74
Q

Glycoprotein produced by the stomach that helps absorb vitamin B12, mostly in the liver
Allows body to store years worth of B12
Prevents loss of B12

A

Intrinsic factor

75
Q

Vitamin B12 is found primarily in this
(diet)

A

Meat products

76
Q

Intrinsic factor is produced by this organ

A

Stomach

77
Q

Condition where an autoimmune reaction frequently leads to destruction of intrinsic factor, and inability to absorb dietary B12
Leads to persistent poor synthesis of RBCs

A

Pernicious anemia

78
Q

Deficiency of B12 can lead to a deficiency of this

A

Folate

79
Q

B12 deficiency leads to folate deficiency because all the folate eventually becomes tied up in this useless form

A

N5-methyl form

80
Q

Megaloblastic anemia in B12 deficiency is due to this

A

Resulting folate deficiency

81
Q

Excess folate can “hide” this characterstic of B12 deficiency

A

Megaloblastic anemia

82
Q

3 major effects of B12 deficiency

A

Neurological damage
Megaloblastic anemia
Neural tube defects

83
Q

Sulfa drugs are analogs of this

A

Para-aminobenzoic acid (PABA)

84
Q

Sulfa drugs are used for what?

A

Antibiotics
Kill bacteria that synthesize their own folate

85
Q

The mechanism of sulfa drugs target bacteria that synthesize this

A

Folate

86
Q

Enzyme that activates folate
1. Folate + NADPH → Dihydrofolate (FH2) + NADP+
2. Dihydrofolate (FH2) + NADPH → Tetrahydrofolate (FH4)

A

Dihydrofolate reductase

87
Q

Methotrexate blocks this

A

NADPH reduction steps converting folate to coenzyme form FH4

88
Q

Potent competitive inhibitor of dihydrofolate reductase
Used in chemotherapy to block folate activation for nucleotide synthesis (dTMP)

A

Methotrexate

89
Q

Inhibitor specific for bacterial dihydrofolate reductase enzyme

A

Trimethoprim

90
Q

2 ways to reduce homocysteine

A

B12 and folate to resynthesize Met
Serine to synthesize Cys (PLP/B6 reactions)

91
Q

Elevated levels of this lead to risk factor for heart disease

A

Homocysteine

92
Q

5 deficiencies that can cause elevated levels of homocysteine

A

B6, B12, and/or folate
Cystathionine synthase of lyase

93
Q

Precursor of dopamine, norepinephrine, and epinephrine

A

Phenylalanine

94
Q

2 precursors to catebholamines

A

Phenylalanine and Tyrosine

95
Q

Parkinson’s disease is associated with defective synthesis of this

A

Dopamine

96
Q

Parkinson’s disease is associated with defective dopamine synthesis due to deterioration of this

A

Substantia nigra

97
Q

Treatment of Parkinson’s disease

A

DOPA (dihydroxyphenylalanine) - crosses blood brain barrier
DOPA decarboxylase inhibitor - doesn’t cross blood brain barrier

98
Q

Immediate precursor of dopamine

A

DOPA

99
Q

Enzyme that methylates on phenolic-OH via SAM of all three catecholamines

A

COMT (Catechol-O-Methyl Transferase)

100
Q

3 catecholamines

A

Dopamine
Norepinephrine
Epinephrine

101
Q

Enzyme that oxidizes amino group of catecholamines

A

MAO (MonoAmine Oxidase)

102
Q

Inhibitors of this enzyme are used to help Parkinson’s patients, slowing the oxidation of dopamine

A

MAO (MonoAmine Oxidase)

103
Q

Enzyme that oxidizes the aldehyde of catecholamines to carboxyl (uses NAD+ as coenzyme)

A

ALDH

104
Q

Excreted product of catecholamine degradation

A

Vanillyl Mandelic Acid (VMA) and related metabolites

105
Q

Frequently measured to determine the activity of adrenal production of catecholamines

A

Vanillyl Mandelic Acid

106
Q

Vanillyl Mandelic Acid is formed from what process?

A

Catecholamine degradation

107
Q

Decarboxylation of tyrosine occurs in certain fermented and processed foods, and yields this molecule

A

Tyramine

108
Q

Amino acid that is decarboxylated in certain fermented and processed foods, such as wines and cheeses

A

Tyrosine

109
Q

Amine which causes elevated blood pressure and headaches by displacing norepinephrine from storage vesicles

A

Tyramine

110
Q

Tyramine displaces this molecule from storage vesicles

A

Norepinephrine

111
Q

Tyramine is normally degraded by this enzyme

A

MAO (MonoAmine Oxidase)

112
Q

Patients taking MAO inhibitors may be particularly sensitive to foods that contain this

A

Tyramine

113
Q

Melanin is derived from this amino acid

A

tyrosine

114
Q

PKU patients can’t make this product of Tyrosine and thus have light pigmentation

A

Melanin

Biochem (21 decks)

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