Biochem Lec 5A - Amino acid: Disposal of Nitrogen Flashcards
second phase of amino acid catabolism
-carbon skeletons of the a-keto acids are converted to common intermediates of energy producing, metabolic pathways
-these compounds can be metabolized to CO2 and water, glucose, fatty acids, or ketone bodies by the central pathways of metabolism
how does nitrogen leave the body
as urea, ammonia, etc
digestion of dietary proteins (stomach)
-HCL denature proteins and kill some bacteria
-pepsin - hydrolze proteins
digestion of dietary proteins small intestine - what does pancreatic proteases and aminopeptidases do
pancreatic proteases - cleave polypeptides
aminopeptidases - produce even smaller peptides and free amino acids
free amino acids are taken where
to enterocytes
peptides are hydroylzed where to aa that are released into the portal system by facilitated diffusion
in the cytosol
presense of what keeps aa safely locked away from oxidative breakdown
a-amino group
if this group removed, produces energy (obligatory step in catabolism of all aa)
one removed, N can be incorporated into other compounds or excreted with the carbon skeleton being metabolized
amonia produced by catabolism of aa is transported where
to the liver
where is urea excreted from where and how did it get there
from liver via blood to kidneys
portion of urea diffuses from blood into intestines and is cleaved to CO2 and NH3 by
bacterial urase
ammonia partly lost in feces and partly reabsorbed into the blood T/F
T
what happens in patients w kidney failure where plasma urea levels are elevated - this promotes a greater transfer of urea from
blood to gut (which contribtute to hyperammonemia)
