Which structure is not affected by protein denaturation?
Ans. is 'a' i.e., Primary * The term denaturation refers to disruption of higher order (secondary, tertiary and quaternary) structure of protein.* All non-covalent bonds that maintain higher order structure are disrupted, but peptide bond (covalent bond) remains intact. Thus, the primary structure is not altered during denaturation, i.e., amino acid sequence is not altered, but denaturation may completely disrupt secondary, tertiary and quaternary structure, e.g., denaturated oligomeric proteins dissociated into subunits, each with a randam coil formation.* Thus denaturation is randamization of conformation of polypeptide chain without disruption of primary structure (amino acid sequence).* Denaturation is always accompanied by a loss of biological function, e.g., enzymes are inactivated and antibodies fail to act with antigens.* Denaturation is generally irreversible, e.g., boiled egg does not regain its original form when kept in cold.* Denatured proteins are less soluble and in many cases they precipitate.* Denaturation causing agents may be heat, detergents and organic solvents, strong acid and bases, 8M urea or 6 M guanidine chloride, heavy metal ions, trichloroacetic acid, and physical agents (X-rays, UV rays, high pressure).
Primary
Secondary
Tertiary
Quartenary
Structure & Function of Protein