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Biochemistry > Amino Acid Metabolism > Flashcards

Amino Acid Metabolism Flashcards

1
Q

Amino acids can be classified as

A

glucogenic & ketogenic

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2
Q

Amino acids whose catabolism yields

A

pyruvate

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3
Q

Amino acids whose catabolism yields pyruvate or one of the intermediates of the citric acid cycle are termed

A

glucogenic

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4
Q

Only exclusively found in proteins like leucine and lysine, which are not substrates for gluconeogenesis, preventing glucose formation.

A

Ketogenic amino acids

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5
Q

Asparagine hydrolyzed by

A

asparaginase

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6
Q

loses its amino group by transamination to form oxaloacetate.

A

Aspartate

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7
Q

can be administered systemically to treat leukemic patients, as it lowers asparagine levels in the plasma, depriving cancer cells of a required nutrient.

A

Asparaginase

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8
Q

This amino acid is converted to glutamate and ammonia by the enzyme glutaminase

A

Glutamine

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9
Q

Glutamine: This amino acid is converted to glutamate and ammonia by the enzyme?

A

glutaminase

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10
Q

Glutamate is converted to α-keto glutarate by transamination, or through oxidative deamination by?

A

glutamate dehydrogenase

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11
Q

This amino acid is oxidized to glutamate. Glutamate is transaminated or oxidatively deaminated to form α-ketoglutarate.

A

Proline

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12
Q

This amino acid is cleaved by arginase to produce ornithine

A

Arginine

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13
Q

This amino acid is oxidatively deaminated by histidase to urocanic acid, which subsequently forms N-formimino glutamate (FIGlu).

A

Histidine

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14
Q

Histidine: This amino acid is oxidatively deaminated by histidase to urocanic acid, which subsequently forms?

A

N-formimino glutamate (FIGlu)

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15
Q

Amino acids that form α-ketoglutarate via glutamate

A
  1. Glutamine
  2. Proline
  3. Arginine
  4. Histidine
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16
Q

Amino acids that form pyruvate;

A
  1. Alinine
  2. Serine
  3. Glycine
  4. Cystine
  5. Threonine
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17
Q

The major gluconeogenic amino acid. This amino acid loses its amino group by reversible transamination to form pyruvate.

A

Alanine

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18
Q

An amino acid can be converted to glycine and N^5, N^10 methylenetetra hydrofolate

A

Serine

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19
Q

Serine can be converted to glycine and N^5, N^10 methylenetetra hydrofolate. It can also be converted to pyruvate by?

A

serine dehydratase

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20
Q

This amino acid can be converted to serine by the reversible addition of a methylene group from N^5, N^10-methylenetetrahydrofolic acid or oxidized to CO2 and NH3.

A

Glycine

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21
Q

Glycine can be converted to?

A

glyoxylate

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22
Q

This amino acid is reduced to cysteine, using NADH + H^+ as a reductant.

A

Cystine

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23
Q

Cysteine undergoes desulfuration to yield?

A

pyruvate

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24
Q

This amino acid is converted to pyruvate or to α-ketobutyrate, which forms succinyl CoA.

A

Threonine

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25
Q

Amino acids that form fumarate:

A
  1. Phenylalanine and tyrosine
  2. Inherited deficiencies
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26
Q

Hydroxylation of phenylalanine produces?

A

tyrosine

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27
Q

in the enzymes of phenylalanine and tyrosine metabolism lead to the diseases phenylketonuria and alkaptonuria, and the condition of albinism.

A

Inherited deficiencies

28
Q

Amino acids that form succinyl CoA:

A

methionine

29
Q

is one of four amino acids that form succinyl CoA.

A

Methionine

30
Q

This sulfur-containing amino acid deserves special attention because it is converted to S-adenosyl methionine (SAM), the major methyl-group donor in one-carbon metabolism.

A

Methionine

31
Q

Methionine is also the source of?

A

homocysteine

32
Q

a metabolite associated with atherosclerotic vascular disease.

A

homocysteine

33
Q

a high-energy compound that is unusual in that it contains no phosphate.

A

SAM

34
Q

is hydrolyzed to homocysteine and adenosine

A

SAH

35
Q

accepts a methyl group from N5-methyltetrahydrofolate (N5-methyl-THF) requiring methylcobalamin.

A

Homocysteine

36
Q

Homocysteine condenses with

A

serine

37
Q

These amino acids are branched-chain amino acids that generate propionyl CoA, which is converted to succinyl CoA by biotin- and vitamin B12–requiring reactions

A

Valine and isoleucine

38
Q

This amino acid is dehydrated to α-ketobutyrate, which is converted to propionyl CoA and then to succinyl CoA.

A

Threonine

39
Q

Amino acids that form acetyl CoA or acetoacetyl CoA:

A
  1. Leucine
  2. Isoleucine
  3. Lysine
  4. Trytophan
40
Q

This amino acid is exclusively ketogenic in its catabolism, forming acetyl CoA and acetoacetate.

A

Leucine

41
Q

This amino acid is both ketogenic and glucogenic, because its metabolism yields acetyl CoA and propionyl CoA.

A

Isoleucine

42
Q

An exclusively ketogenic amino acid, this amino acid is unusual in that neither of its amino groups undergoes transamination as the first step in catabolism.

A

Lysine

43
Q

This amino acid is both glucogenic and ketogenic because its metabolism yields alanine and acetoacetyl CoA.

A

Tryptophan

44
Q

Removal of the amino groups of all three amino acids is catalyzed by a single, vitamin B6–requiring enzyme, branched-chain amino acid aminotransferase.

A

Transamination

45
Q

Removal of the carboxyl group of the α-keto acids derived from leucine, valine, and isoleucine is catalyzed by a single multienzyme complex, branched-chain α-keto acid dehydrogenase complex.

A

Oxidative decarboxylation

46
Q

Oxidation of the products formed in the above reaction yields α-β-unsaturated acyl CoA derivatives.

A

Dehydrogenation

47
Q

a carrier of one-carbon units

A

Folic acid

48
Q

is produced from folate by dihydrofolate reductase in a two-step reaction requiring two NADPH.

A

tetrahydrofolic acid (THF)

49
Q

allows one-carbon compounds to be recognized and manipulated by biosynthetic enzymes.

A

tetrahydrofolic acid (THF),

50
Q

Most important disease of amino acid metabolism because it is relatively common and responds to dietary treatment. This is caused by a deficiency of phenylalanine hydroxylase. It is a common inborn amino acid metabolism error, characterized by phenylalanine accumulation and tyrosine deficiency.

A

Phenylketonuria (PKU)

51
Q

may also caused by enzyme deficiencies required to synthesize BH4, or in dihydropteridine reductase, which regenerates BH4 from BH2.

A

Hyperphenylalaninemia

52
Q

Characteristics of classic PKU:

A
  1. Elevated phenylalanine
  2. CNS symptoms
  3. Hypopigmentation
53
Q

is present in elevated concentrations in tissues, plasma, and urine.

A

Phenylalanine

54
Q

Mental retardation, failure to walk or talk, seizures, hyperactivity, tremor, microcephaly, and failure to grow are characteristic findings in

A

Phenylketonuria

55
Q

The hydroxylation of tyrosine by tyrosinase, which is the first step in the formation of the pigment melanin, is competitively inhibited by the high levels of phenylalanine present in?

A

Phenylketonuria

56
Q

is a treatable disease that requires early diagnosis due to its treatable nature

A

Phenylketonuria

57
Q

is a family of diseases caused by over 100 mutations in the phenylalanine hydroxylase (PAH) gene, with frequency varying among populations and often doubly heterozygous

A

Classic PKU

58
Q

is an essential amino acid and a key component of most natural proteins.

A

Phenylalanine

59
Q

When a woman with PKU who is not on a low-phenylalanine diet becomes pregnant, the offspring will be affected with?

A

maternal PKU syndrome

60
Q

is a rare autosomal recessive disorder characterized by a partial or complete deficiency in branched-chain α-keto acid dehydrogenase, an enzyme complex that decarboxylates amino acids.

A

Maple syrup urine disease (MSUD)

61
Q

is a disorder with a classic type and several variant forms.

A

Maple syrup urine disease (MSUD)

62
Q
  • Defect in tyrosine metabolism leads to melanin production deficiency.
  • Causes partial or full absence of pigment from skin, hair, and eyes.
A

Albinism

63
Q

also known as tyrosinase-negative oculocutaneous albinism, results from copper-requiring tyrosinase deficiency.

A

Complete albinism

64
Q

are inherited as autosomal recessive illnesses caused by a defect in the enzyme cystathionine β-synthase

A

Homocystinurias

65
Q

• A Rare Metabolic Condition
• Deficiency in homogentisic acid oxidase leads to accumulation of homogeneic acid.
• Symptoms include homogentisic aciduria, large joint arthritis, and black ochronotic pigmentation of cartilage and collagenous tissue.
• Usually asymptomatic until age 40, with occasional diaper staining.

A

Alkaptonuria

Biochemistry (10 decks)

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