General Veterinary Biochemistry

Classification of amino acids based on nutritional requirement

CLASSIFICATION BASED ON NUTRITIONAL EQUIREMENT

• There are two main classes based upon their requirement in the diet particularly for monogastric animals.

Essential amino acids

• They cannot be synthesized in the body. They have to be supplied in the diet.
• Eg: methionine, arginine, threonine, tryptophan, valine, isoleucine, leucine, phenylalanine, histidine and lysine. Of the ten listed above, two amino acids namely arginine and histidine can be partly synthesized by adult humans – hence called as Semi-essential amino acids .

Non-essential amino acids

• The other ten amino acids can be synthesized in the body – hence called as Non-essential amino acids.
• Eg: glycine, alanine, serine, tyrosine, cysteine, glutamic acid, aspartic acid, asparagine, glutamine and proline.