Nitrogen Metabolism Flashcards
what is the final step to nitrogen removal?
oxidative deamination (glutamate dehydrogenase will oxidatively deaminate glutamate to form ammonia
how are amino acids converted to glutamate?
via transamination reactions
what do transamination reactions require?
PLP
what is the role of CPSaseI?
it uses the free ammonium to form carbamoyl phosphate which then feeds into the urea cycle
Hartnup disease affects membrane transport of what amino acids?
neutral amino acids
Cystinuria affects the membrane transport of what amino acids?
dibasic amino acids
as filtrate passes through the PCT, transport proteins from what gene superfamily mediate the reuptake of amino acids and glucose?
from the SLC (solute carrier) gene superfamily
what specific amino acid is not reabsorbed in Hartnup’s disease?
tryptophan
what specific amino acids are not absorbed in Cystinuria?
COAL (cystine, ornithine, arginine, and lysine
what is tryptophan a precursor of?
serotonin, melatonin, and niacin
what is niacin a really important precursor for?
formation of NAD
what is the inheritance like of cystinuria?
it is autosomal recessive- males
what does cystinuria result in?
the formation of cystine renal calculi
What causes PKU?
a defect in the reaction that converts Phe–> Tyr (defect in phenylalanine hydroxylase
what is secondary (non-classical PKU)?
a dihydrobiopterin reductase deficiency
what are the toxic substances associated with PKU?
phenyllactate and phenylacetate
what causes the musty odor associated with PKU?
phenyllactate
what is the essential cofactor of phenylalanine hydroxylase?
tetrahydrobiopterin
what is used in treatment of secondary PKU?
synthetic THB
what causes transient tyrosinemias in newborns?
delayed expression of 4-HPPD
what causes tyrosinemia type 1?
defect in fumarylacetoacetate hydrolase
what is the go to treatment for tyrosinemia type 1?
nitisinone
what is tyrosinemia type 2 caused by?
defective tyrosine aminotransferase
clinical signs of tyrosemia type 2?
occular manifestations including excessive tearing, redness, pain, and photophobia
what causes tyrosinemia type 3?
defective 4-HPPD
what causes alkaptonuria?
defective homogentisate oxidase
what accumulates in alkaptonuria?
homogentisic acid
what is the characteristic triad of alkaptonuria?
homogentisic aciduria, dark sclera, and arthritis
what enzyme is responsible for converting glutamate into alpha ketoglutarate?
glutamate dehydrogenase
what enzyme is responsible for converting amino acids into alpha keto aicd?
amino transferases
what enzyme is responsible for converting glutamate into glutamine?
glutamine synthase
what enzyme is responsible for converting glutamine into glutamate?
glutaminase
