Amino Acid Metabolism EC Flashcards Preview

Evan's Step 1 Prep Material > Amino Acid Metabolism EC > Flashcards

Flashcards in Amino Acid Metabolism EC Deck (21):
1

Nitrogen containing substances are used in the synthesis of what compounds?

Nucleotides
Neurotransmitters
Hormones
Porphyrins
Nonessential amino acids

2

What are the essential amino acids?

Phenylalanine
Valine
Tryptophan
Threonine
Isoleucine
Methionine
Histidine
Leucine
Lysine

3

Which amino acids are acidic?

Aspartate
Glutamate

4

Tremor, slurred speech, somnolence, vomiting, cerebral edema, and blurred vision

Ammonia intoxication
Liver disease or urea cycle enzyme deficiency
NH4 accumulates and depletes a-ketoglutarate (blocks TCA)

5

What happens to carbon skeletons of amino acids after the ammonia has been removed?

They are degraded and become intermediates in the TCA cycle

Some are ketogenic: Lysine & Leucine
Some are both: Isoleucine, Phenylalanine, Typrtophan, & Tyrosine
Some are glucogenic: rest

6

Tyrosine derivatives

Thyroid hormones
DOPA (dopamine, NE/Epi, melanin)

7

Methionine

S-Adenosylmethionine (SAM) - methyl group transfers
Homocysteine
Cysteine

8

Tryptophan

Niacin
Serotonin
Melatonin

9

Glutamate

GABA
Glutathione

10

Glycine

Porphyrin (heme)

11

Arginine

Creatine
NO
Urea

12

Histidine

Histamine

13

Phenylalanine

Tyrosine (dopa, thyroid hormones)

14

What does phenylalanine hydroxylase do?

Convert Phenylalanine to Tyrosine

15

Man presents with knee and back pain. Dark spots on conjunctiva and nasal bridge. Urine turns dark if forgets to flush.

Alkaptonuria
Defective homogentisic acid oxidase (degrades tyrosine)
Tyrosine, Phenylalanine, and Homogentisic acid build up

16

Presents to ER with sudden severe, intermittent right flank pain w/ n/v. Urinalysis shows hematuria. Kidney stones with cysteine crystals found.

Cystinuria
Defective transport of Cysteine, Ornithine, Arginine, & Lysine "COAL"

*Cystosis* - intralysosomal accumulation of cysteine

17

Fanconi Syndrome

Renal proximal tubule dysfunction (hypophosphatemia, glycosuria, amino aciduria, hypokalemia)

Growth retardation, rickets, polyuria, dehydration, metabolic acidosis, photophobia.

18

Man complaining of photosensitive rash on face and neck and extensor surfaces. Has been feeling more irritable than normal and is somewhat ataxic. Eats healthy with a well balanced diet.

Hartnup disease
Mutation in neutral a.a. transporter
Tryptophan excreted in urine and not absorbed in gut
Leads to niacin deficiency-pellagra

19

7 yo boy presents complaining of diminished visual acuity. On p/e, lenticular dislocation found along with abnormally long fingers. Has mild mental retardation. Labs reveal elevated serum methionine and urine homocysteine.

Homocystinuria

Defects:
Cystathionine synthase (or PP/B6 cofactor affinity). Homocysteine methyltransferase

Homocysteine accumulates-
toxic to vascular endothelium (atherosclerosis),
interferes with collagen formation (ocular/skeletal)

20

4 day old infant presents because vomiting and urine smells sweet. Moro reflex absent and rigid. Labs show metabolic acidosis.

Maple Syrup Urine Disease
Defect in BCKD (branched chain ketoacid dehydrogenase)
Diminished breakdown of Isoleucine, Leucine, & Valine
"I Love Vermont Maple Syrup"

Ketoacids toxic to brain
Branched chain a.a.'s in urine lead to sweet smell

21

2 y/o blonde haired blue eyes immigrant presents with possible developmental delays. Hypertonia and hyperreflexia and smells "musky". Guthrie test positive, phenylketones in urine.

PKU (phenylketonuria)
Defect in Phenylalanine Hydroxylase or tetrahydrobiopterin cofactor (converts phenylalanine to tyrosine)
Phenylalanine buildup causes brain damage (and becomes deficient in tyrosine derivatives)
Avoid foods w/ phenylalanine (aspartame)

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