Protein structure not lost in denaturation is ?

Ans. is 'a' i.e., Primary structure The term denaturation refers to disruption of higher order (secondary, teiary 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, teiary and quaternary structure, e.g., denaturated oligomeric proteins dissociated into subunits, each with a randam coil formation.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.