What is the overall flow of nitrogen in amino acid catabolism?
Four steps = transamination, oxidative deamination, ammonia transport, urea cycle..
Why is glutamate important in amino acid catabolism?
Transamination is the process which interconverts a pair of amino acids and a pair of keto acids by transfer of the alpha amino group. Transaminases are specific for one pair, but not for the other. For e.g. alanine transaminase is specific for pyruvate to alanine and vice versa, the other pair being any amino acid - keto acid pair. The reaction below can be catalyzed by either alanine transaminase or glutamate transaminase.
Of the various transaminases, glutamate transaminase is the most important one in urea synthesis. It is the only amino acid that undergoes oxidative deamination (the next step, see above) at an appreciable rate. Thus the nitrogen from amino acids towards urea is channeled through glutamate. Alpha ketoglutarate accepts the amino group to form L-glutamate.
How does ammonia cause toxicity in the brain OR how does the brain handle ammonia under ordinary circumstances and when the ammonia levels are high?
How are the steady state amino acid levels maintained in the blood OR what are the interactions of amino acid metabolism with carbohydrate metabolism?
What is the algorithm for diagnosis in a patient with hyperammonemia?
