Nitrogen 1-3 Flashcards
Where is nitrogen found in the body?
Ammonia
Amino acids
Urea
What enzymes required for nitrogen from plants (nitrogen fixation)
Nitrogenase
Nitrogenase
Live anaerobically
Burn off oxygen in cells
form heterocytes whose cell wall prevents oxygen entering
What do leguminous plants produce to keep oxygen concentration low?
leghemoglobin
What is the only amino acid that obtains nitrogen directly from NH4?
Glutamate
Keto acid amino acid
Amino group added or taken away eg glutamate to CAC intermediate alpha keto glutarate
Transamination
Transfer amino groups
Readily available and no loss of nitrogen
L-glutamine
Temporary store of nitrogen
Amino transferases
rely on PLP from vitamin B
Presence indicates cell damage
3 times amino acids are oxidised
- left over
- dietary
- proteins in body eg starvation
Stomach degradation
Pepsin in acidic environment to peptides
Small intestine
large peptides - trypsin
Small peptide - ammopeptidase
Ubiquitin
Linked to protein and fed into proteasome - degradation and leave carbon skeleton
Fates of nitrogen
- aquatic = release ammonia, diffusion in gills
- plant = conserve nitrogen
- terrestrial vertebrate = excrete ammonia as urea
- birds and reptiles = uric acid
- humans and apes = urea and uric acid
What is ammonia safely transported in blood as?
Glutamine
Where is excess glutamine processed?
Liver, kidneys and intestine
Why must alanine or glutamate used to transport nitrogen in blood?
No charge - cross membrane
Urea cycle forms
Carbamoyl phosphate
Amino acids form glucose/glycogen
Gluconeogenic
Aminoa cids feed into acetyl coA/acetoacetate
Ketogenic
PKU
Deficient in PAH so increased phenylalanine levels
Heel prick on Guthrie card
