The amino acids are the fundamentals units of protein structure. All amino acids contain at least one amino group (-NH2) in the alpha position and one carboxyl, and all (except Glycine) contain an asymmetric carbon atom. For this reason, they may exist as isomers.
The term amino acid might mean any molecule containing both an amino group and any type of acid group; however, the term is almost always used to refer to an carboxylic acid. The simplest acid is aminoacetic acid, called glycine.
Amino acids play major role in regulating multiple processes related to gene expression, including modulation of the function of the proteins that mediate messenger RNA (mRNA) translation.
Most naturally occurring amino acids are of the L-configurations, although D-amino acids are not uncommon in some microorganisms. The presence of a D-amino acid oxidase in mammalian tissue, however, suggests that the D-forms may play some yet unrecognized role in mammalian protein metabolism.
Based on their nutritional/physiological roles, amino acids can be differentiated as:
• Essential amino acids: Valine, leucine, isoleucine, phenylalanine, tryptophan, methionine, threonine, histidine (essential for infants), lysine and arginine (“semi-essential”).
• Nonessential amino acids: Glycine, alanine, proline, serine, cysteine, tyrosine, asparagine, glutamine, aspartic acid and glutamic acid.
Amino acids are utilized in formation of protein. If amino acids are deficient, then protein synthesis does not occur. As a result protein deficiency disease may occur. It is necessary to take balanced diet containing all essential amino acids.
Amino acids – fundamental units of protein
