Essential Amino Acids and Nonessential Amino Acids in Evolution

Abstract

Nomenclature of “essential” and “nonessential” amino acids has been argued, because the term “nonessential” is not accurate from biochemical and nutritional point of view. Essentiality of amino acids is mainly dependent on the carbon skeleton. Some nonessential amino acids become indispensable in certain disease states or certain developmental stage. Essential amino acids are synthesized through longer steps of enzyme reaction than nonessential amino acids in prokaryote. This may be a major reason that the ability of essential amino acids synthesis has been lost in some species including human. Although prokaryote, plants and fungi are able to synthesize all amino acids, animals and some of protozoa lose the ability of synthesis of essential amino acids. The origin of essential amino acid occurred during the evolution from protozoa to metazoa.