Define the following as related to proteins (i) Primary structure (ii) Peptide linkage (iii) Denaturation.
Define the following as related to proteins (i) Primary structure (ii) Peptide linkage (iii) Denaturation.

(i) Primary structure

When we discuss the primary structure of a protein, we refer to the exact sequence in which the amino acids are present. For example, the sequence of amino acid linkages in a polypeptide chain. In each protein, the amino acids are organized in a particular order. A slight variation in the arranging sequence results in an entirely different protein.

(ii) Peptide Linkage
A peptide linkage is an amide formed as a result of the removal of a water molecule between the –COOH group of one amino acid molecule and the -NH2 group of another amino acid molecule.

(iii) Denaturation

Within a biological system, each protein has its own three-dimensional structure and biological activity. When we subject a protein to a physical change, such as a change in temperature, or a chemical change, such as a change in pH, its H – bonds are disrupted or altered.

This causes the globules to unfurl and the helixes to uncoil. And as a result of this alteration, the protein loses its biological activity. Denaturation refers to the loss of the biological activity of a protein. The primary structure is not altered during this process, but the tertiary and secondary structures are destroyed. 

The coagulation of egg white when an egg is boiled is an example of protein denaturation.