Amino acids are the building blocks of proteins and their numbers found to be twenty. Out of which eight are essential for animals and used as essential food supplements. General skeleton of amino acids:

Amino acids is distinguished by substitution of R-group on the carbon atom which influences the activity of the amino acid and divided into the following groups: amino acids with aliphatic R groups, non-aromatic amino acids with hydroxyl R groups, amino acids with sulfur containing R groups, amino acids with acidic R groups, amino acids with basic R groups, amino acids with aromatic R groups and amino acids with imino acids as the R groups. Thus, the hydrophilic amino acids have hydroxyl groups in their R substituent (e.g. serine) tend to interact with the aqueous environment and often involved in the formation of H-bonds which in turn predominantly found on the exterior surfaces proteins or in the reactive regions of enzymes. However, the hydrophobic amino acids do not have hydroxyl groups in the R substituent (e.g. methionine) and usually repelling the aqueous environment as well as reside predominantly in the interior of proteins. This class of amino acids does not ionize nor participate in the formation of hydrogen bonds. All the amino acids, except glycine have two optically active isomers, the D and L forms. Most of natural proteins are usually made up of L-amino acids (natural amino acids.)

Role of amino acids
Amino acids have important role in food & pharmaceutical industries, therapeutic purposes, preparation of cosmetics and in the synthesis of chemicals too.
1.Use as nutritional supplementation: Most of absorbed amino acids are used to replace body proteins during their metabolism. Eight amino acids are known to be essential in diet. Foods such as plant proteins lacking in these essential amino acids are fortified with their addition. Most cereals are considerably low in lysine and hence cereal food is improved by the addition of essential amino acids determined by the PER (protein equivalency ration). The PER is logistic scale of comparing the amino acid contents of protein with that of hen's egg or human milk. An animal feed is improved by addition of lysine and methionine resulting in higher growth rates in the animals.

2.Flavoring of foods stuffs: Amino acids are commonly used to influence the taste of meats. Some are used to sweeten the foodstuffs and beverages such as glycine, L- aspartyl, L - phenylalanine methyl ester and aspartame. Other amino acids e.g. valine, L- isomers of leucine, phenylalanine, tyrosine, and tryptophan are bitter while their D-isomers are sweet. Thus, combination of various amino acids influences the taste and flavor of foods and drinks. Thus cheese flavor also influenced by using the combined effect of glutamic acid, valine, leucine and methionine as well.

3.Medical uses: The marvelous application of amino acids in medicine is the uses of these amino acids as food supplements as protein rich diet and administered orally after operation/critical surgery. Various amino acids are used for ammonia detoxification in blood in liver diseases, in the treatment of heart failure, in cases of peptic ulcer and to treat the male sterility.

4.Use as industrial raw materials: Although numerous studies have been concluded on the use of amino acids as raw materials in the chemical industry and best example in the manufacturing of artificial silk. However amino acids are used as surface-active agents, synthesis of polymers, synthetic leather, fire-resistant fabrics and anti-static materials as well as in preparation of antidandruff shampoos too.

About Author / Additional Info:
Dr. Kirti Rani Sharma,
Assistant Professor (II),
Amity Institute of Biotechnology,
Amity University, sec-125, Gautam Buddha Nagar, Noida-201303 (UP), India.
Office Phone no: +91-120-4392946
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