Nitrogen metabolism Flashcards
What is the rate-limiting step of nitrogen metabolism?
NH4+ => carbamoyl phosphate via carbamoyl phosphate sythetase (CPS) I
What amino acid is taken from the muscle converted to glutamate? Via what chemical transformation?
Alanine => glutamate via transamination
Transporters for what are defective in Hartnup’s disease?
Nonpolar amino acids
Transporters for what are defective in Cystinuria?
Dibasic amino acids
Where in the nephron does amino acid and glucose reabsorption occur?
proximal convoluted tubule
What 4 things is tryptophan a precursor for?
serotonin, melatonin, niacin, NAD
What disease is associated with tryptophan deficiency and what are other associated sxs?
Hartnup’s
failure to thrive, nystagmus, ataxis, tremor, pellegra-like dermatitis, photosensitivity
Hartnup treatment
Niacin supplementation
What is deficient in secondary/non-classical PKU?
THB (coenzyme for Tyr synthesis)
What is deficiency is primary/classical PKU?
phenylalanine hydroxylase (enzyme for Phe=>Tyr)
In PKU, what is Phe converted to?
phenylpyruvate
phenyllactate
phenylacetate
What results from PKU and why?
irreversible neurological damage resulting from phenylalanine toxicity
What enzyme is deficient in hereditary infantile tyrosinemia AKA tyrosinemia type I?
fumarylacetoacetate hydrolase - final step in conversion of Tyr => fumarate
What enzyme is deficient in Tyrosinemia type II
tyrosine aminotransferase
What enzyme is deficient is tyrosinemia type III
p-hydroxyphenyl-pyruvate oxidase
