The name “Protein” is given by Berzelius in 1938. The word protein is derived from the Greek word, “proteios” which means primary or of prime importance because proteins are the most important chemical substances which are necessary for growth, repair and development of life.
Proteins are found in all living cells. Main sources of proteins are milk, cheese, pulses, peanuts, fish, meat, etc. They occur in every part of the body and form the fundamental basis of structure and functions of life. In humans, hair, skin, haemoglobin, nails, enzymes and cells etc., are made of proteins.
Composition of Proteins:
Proteins are the high molecular mass complex biopolymers of amino acids and organic compounds that are most important for life. Chemically, all proteins are nitrogen-containing carbon compounds. All proteins contain the elements carbon, hydrogen, oxygen, nitrogen and sulphur some of these may also contain phosphorus, iodine and traces of metals like iron, copper, zinc and manganese. Amino acids are liberated when proteins are hydrolyzed. Proteins are the polymers of α – amino acids.
On partial hydrolysis of proteins, peptides of different molecular weight are obtained which on complete hydrolysis gives α – amino acids. This means that proteins are polypeptides of α – amino acids. Their molecular weight is more than 10,000. These are monodisperse natural polymers.
