Nitrogen Metabolism Flashcards
(11 cards)
Outline the ENDOGENOUS synthesis of nucleotides.
Purines: Requires Glutamine, glycine, aspartate via inosine
Pyrimidines; AAs via carbomyl phosphate (synthesised in cytosol)
Thermodynamically costly!!
What is the structure of pyrodoxal phosphate and what is it a cofactor of?
pyridoxine is B6
OHmethyl group of cofactor at position 4 oxidised to ALDEHYDE which is its functional group.
Transaminase (specific for each AA except thr and leu)
What essential molecules does nitrogen make?
ribonucleic acid (genetic continuity, development). proteins
where is glutamate dehydrogenase and why is it important?
primarily in liver mitochondria (IMM)
responsible for around 75% nitrogen flux
irreversible reaction.
where is glutamate dehydrogenase and why is it important?
primarily in liver mitochondria (IMM)
responsible for around 75% nitrogen flux
irreversible reaction.
Briefly outline renal excretion of urea.
around 40% is passively reabsorbed by diffusion in renal tubules.
renal excretion is not efficient!!
What is the sodium benzoate alternative excretion pathway?
activated by CoA
conjugates with glycine in the liver
forms hippuric acid
efficiently excreted by filtration and active transporter for organic acids - efficient.
1 amino nitrogen.
what is the sodium phenylbutyrate alternative excretion pathway?
activated by CoA
metabolised to phenyacetate
conjugates with glu in liver and kidney
phenylacetylglutamine
excreted by filtration and tubular secretion
2 amino nitrogens.
why is arginosuccinate lyase deficiency less severe than OTC and arginosuccinate synthetase deficiency?
arginosuccinate is actively secreted by kidneys and has 2 amino nitrogens so excretion of N better than as urea!
What enzymes do succinylacetone form strong schiff bases with?
Lys side chain amino groups in active site of tyrosine aminotranferase and porphobilinogen synthase.
from fumarylacetoacetase deficiency!
What results from alpha-amino adipic semi-aldehyde dehydrogenase deficiency?
piperidine 6 carboxylate accumulates
condenses with pyridoxal phosphate
(treat with pyridoxine, pyridoxal phosphate is replenished and fits cease!!)
