Flashcards in Amino Acid Metabolism EC Deck (21):
Nitrogen containing substances are used in the synthesis of what compounds?
Nonessential amino acids
What are the essential amino acids?
Which amino acids are acidic?
Tremor, slurred speech, somnolence, vomiting, cerebral edema, and blurred vision
Liver disease or urea cycle enzyme deficiency
NH4 accumulates and depletes a-ketoglutarate (blocks TCA)
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
DOPA (dopamine, NE/Epi, melanin)
S-Adenosylmethionine (SAM) - methyl group transfers
Tyrosine (dopa, thyroid hormones)
What does phenylalanine hydroxylase do?
Convert Phenylalanine to Tyrosine
Man presents with knee and back pain. Dark spots on conjunctiva and nasal bridge. Urine turns dark if forgets to flush.
Defective homogentisic acid oxidase (degrades tyrosine)
Tyrosine, Phenylalanine, and Homogentisic acid build up
Presents to ER with sudden severe, intermittent right flank pain w/ n/v. Urinalysis shows hematuria. Kidney stones with cysteine crystals found.
Defective transport of Cysteine, Ornithine, Arginine, & Lysine "COAL"
*Cystosis* - intralysosomal accumulation of cysteine
Renal proximal tubule dysfunction (hypophosphatemia, glycosuria, amino aciduria, hypokalemia)
Growth retardation, rickets, polyuria, dehydration, metabolic acidosis, photophobia.
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.
Mutation in neutral a.a. transporter
Tryptophan excreted in urine and not absorbed in gut
Leads to niacin deficiency-pellagra
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.
Cystathionine synthase (or PP/B6 cofactor affinity). Homocysteine methyltransferase
toxic to vascular endothelium (atherosclerosis),
interferes with collagen formation (ocular/skeletal)
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