Protein word is taken from a Greek word “prota†which means “primary importanceâ€. Jons Jakob Berzelius, a Swedish scientist gave it a name in 1838 but the important role of protein was fully appreciated after 1926.
Proteins are the primary substance of living organisms as it provides the molecular machinery to the cells of living organisms. Some proteins have structural and mechanical roles in the body like they form struts and joint of cytoskeleton. Protein is a source of nutrition for all the living organisms that are not able to produce or make energy through direct sunlight. It is the most important constituent of the body tissues which are very useful in the growth and repair of cells. It is also very useful in supplying energy when carbohydrates and fats are not available.
Structure
They are made up of amino acids and these amino acids are found in different three dimensional shapes. These shapes depend on the sequence of amino acids in the proteins. Biochemist says about four types of proteins structure
1) Primary structure
2) Secondary structure
3) Tertiary structure
4) Quaternary structure
Proteins may form several similar structures for the better performance of their function. For this tertiary and quaternary are referred as “conformationsâ€. Primary structure is firmed by covalent peptide bond while tertiary are formed by hydrogen bonds.
When the long chain of amino acids is formed then they are called as the proteins and short ones are known as polypeptides or peptides. Polypeptides may not have the tertiary structure and can act as a hormone instead of acting as an enzyme or structural element.
