(i) A peptide linkage is an amide (—CO— NH —) linkage formed between —COOH group of one aamino acid and —NH2 group of other a-amino acid by loss of a water molecule.
(ii) The specific sequence in which various a-amino acids present in a protein are linked to one another is called its primary structure. Any change in its primary structure creates a new protein.
(iii) Denaturation of Proteins: When a protein in its native form is subjected to a change, such as change in temperature or change in pH, the hydrogen bonds are *****. Due to this, globules unfold and helix get uncoiled and protein loses its biological activity. This is called denaturation of protein. During denaturation, 2° and 3° structures are destroyed but 1° structures remain intact, e.g., coagulation of egg while on boiling, curdling of milk, etc.
