MBIO 2370 Lecture Notes - Lecture 9: Transamination, Tyrosinase, Tetrahydrofolic Acid
1 Mar 2017
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Document Summary
Muscle makes alanine and glutamine to transport nh3 to the liver: makes glutamate. What happens to excess nh3: nh3 is toxic - must be removed- especially in brain cells. High nh3 - activates glutamate deh2ase/glutamine synthetase and produces glutamate and glutamine, which uses atp and nadh, causing low energy and damage to the brain. Also, high levels of glutamate draws water into brain cells by osmosis, causes swelling of brain and coma: nh3 converted to urea - non toxic and water soluble, and excreted. Part of this series of reaction is also the biosynthesis pathway for arginine, but only those organisms that have arginase can produce urea. Occur in two compartments: carbonyl phosphate acts as a carrier in the mitochondrial matrix, the nh2 enters the urea cycle in the cytosol through the conversion of ornithine into citrulline. Citrulline diffuses out of mitochondria to cytosol: two nh2 are required for urea.
