Amino acid metabolism Flashcards
what causes maple syrup disease?
deficiency of the enzyme branched-chain alpha-keto acid dehydrogenase leading to a build-up of valine, leucine & isoleucine.
note: it’s autosomal recessive
what causes phenylketonuria?
absence or deficiency of the enzyme phenylalanine hydroxylase leading to a build-up of phenyalanine.
what causes alkaptonuria?
absence of the enzyme homogentisate oxidase leading to a build-up of homogentisate which is excreted in the urine (black urine)
what do these in-born errors of amino acid metabolism diseases mostly cause?
neurological disorders and mental retardation
Essential amino acids?
- Phenylalanine
- Valine
- Threonine
- Tryptophan
- Isoleucine
- Methionine
- Histidine
- Leucine
- Lysine
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Non-essential amino acids?
- Alanine
- Arginine
- Asparagine
- Glutamate
- Glutamine
- Cysteine
- Aspartate
- Glycine
- Tyrosine
- Proline
- Serine
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How is glutamine synthesized?
when a second amino group is added to glutamate using the energy from the hydrolysis of ATP
How is tyrosine synthesized?
from phenylalanine and O2 using phenylalanine hydroxylase
The carbon skeletons of 20 fundamental amino acids are funneled into which seven molecules?
- pyruvate
- acetyl CoA
- acetoacetyl CoA
- alpha-ketoglutarate
- succinyl CoA
- fumarate
- oxaloacetate
what is the rate limiting step of the urea cycle?
the 1st reaction: ammonium ions to carbamoyl phosphate
what is the urea cycle?
the conversion of ammonia (from amino acid degradation) to urea in the liver
note: the urea is excreted in the urine by the kidney
