ABSTRACT
Nonessential amino acids are those that can be synthesized, essential amino acids have to be taken in the diet. The 20 standard amino acids can be grouped into six biosynthetic families depending on the metabolic intermediate from which their carbon skeleton is derived. Amino acids are degraded by the removal of the a-amino group and the conversion of the resulting carbon skeleton into one or more metabolic intermediates. Prior to the metabolism of their carbon skeletons into a major metabolic intermediate, the a-amino group of the amino acid has first to be removed by a process known as transamination. The amino acid is then hydrolyzed to form an a-keto acid and pyridoxamine phosphate, the a-amino group having been temporarily transferred from the amino acid substrate on to pyridoxal phosphate. The major route for the deamination of amino acids is transamination followed by the oxidative deamination of glutamate.
