So we want to eliminate ammonium, and we want to attach an oxygen. And so this is catalyzed by glutaminase, which uses water to basically remove this ammonium, and we form this oxygen as shown in this molecule. So we form our glutamate. So in metabolizing glutamine to alpha ketoglutrate, we have to first form glutamate. And then the glutamate is transformed into alpha ketoglutrate by the activity of this enzyme. Now let's move on to five histidine.