Glutamate: Central Role

As we saw, in amino acid metabolism, glutamic acid or glutamate is central to the balancing of the amines and the ammonium ions that are produce during amino acid metabolism. And we're going to see how that happens in the body as well with this slide. Now this is a complicated slide, so I'm going to step you through it sequentially and fairly carefully to make sure all the points are made. First of all, glutamic acid can be converted to glutamine by the enzyme glutamine synthetase. That reaction is important from a nitrogen balance perspective because ammonium ions are produced as a byproduct of amino acid metabolism. They have to be sopped up as it were. And they're sopped up partly by this reaction. Glutamine could be converted back to glumatic acid, but you'll notice this is not the exact reverse of the reaction that produced the glutamine. Instead the amine that was put on to glutamine, the ammonium that was put on to glutamine to make the amine is converted back onto an alanine. So that what is happened in the process of going up and the then down in this reaction is the ammonium ion on the left has been converted into an amine that is carried on an alanine. Ammonium ion is toxic. The amine on alanine is not. Now alanine as we will see plays into the glucose alanine cycle. Glutamic acid can also be converted into alpha-ketoglutarate as we have seen in the amino acid metabolism and the byproduct to that reaction is the release of an ammonium ion. Now there are places in the body where we want to sop up ammonium that place in the body being the brain. And there are places in the body where we want to release ammonium...