Living systems are made up of Proteins .They are the dehydration polymers of amino acids.Each amino acid residue is joined by a peptide linkage to form proteins. Proteins are the molecular instruments in which genetic information is expressed, Hormones, Antibodies,transporters, the lens protein, the architectural framework of our tissues and a myriad of substances having distinct biological activities are derived. The type, nature and number of amino acids impart characteristic properties to the proteins.There are about 300 amino acids, but only 20 are coded by DNA of higher organisms. Acid-base properties of amino acids are important to the individual physical and chemical nature of the protein. The structural organization of proteins could be primary, secondary, tertiary and quaternary. The three dimensional structure is the most biologically active one.The unfolding and disorganization of the proteins results in denaturation, the process is mostly irreversible. Such a protein may lose its biological function. Many amino acid derived peptides are of biological importance and special products formed from them are of critical importance to the body.