Amino acid: Brief overview

Proteins have an amazing range of structural and catalytic properties as a result of  their varying amino acid composition. Because of this versatility, proteins serve an astonishing variety of functions in living organisms.

Amino acids are the building blocks of proteins; they contain a carboxylic acid group and an amino group on the alpha (α) carbon, the carbon adjacent to the C=O; because they have both a weak acid and weak base present, they actually exist as a salt.

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.

The physical and chemical properties of a protein are determined by its constituent amino acids. The individual amino acid subunits are joined by amide linkages called peptide bonds.

The simplest acid is α-amino acetic acid, called glycine. Other common amino acids have side chains (symbolized by R) substituted on the carbon atom. For example, alanine is the amino acid with a methyl side chain.

Unlike most organic compounds, amino acids are soluble in water, have either high melting points or decompose upon heating. They act more like inorganic materials than organic compounds.

The standard amino acids are 20 common α-amino acids that are found in nearly all  proteins. The standard amino acids differ from each other in the structure of the side chains bonded to their carbon atoms. All the standard amino acids are L-amino acids.

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 acid: Brief overview