Glutamine and Glutamate with Proline, Histidine, Arginine and Ornithine, comprise 25% of the dietary amino acid intake and constitute the "Glutamate family" of amino acids, which are disposed of through conversion to Glutamate. The carbon skeletons of these five amino acids enter the tricarboxylic acid cycle via Alpha-Ketoglutarate. The catabolism of Arginine begins within the context of the Urea cycle. It is hydrolyzed to Urea and Ornithine by Arginase. Ornithine, in excess of Urea cycle needs, is transaminated to form Glutamate Semialdehyde. Glutamate Semialdehyde can serve as the precursor for Proline biosynthesis or it can be converted to Glutamate. Proline catabolism is a reversal of its synthesis process. The Glutamate Semialdehyde generated from ornithine and proline catabolism is oxidized to [...]