Denaturation of Protein

Loss of primary structure REF: Lehninger Principles of Biochemistry, 4th Edition, page 147

“Protein denaturation leads to loss of Quaternary, Tertiary & Secondary functions, but the primary structure is preserved”

Denaturation is a phenomenon that involves transformation of a well-defined, folded structure of aprotein, formed underphysiological conditions, to an unfolded state under non-physiological conditions

Types of Denaturation: Temperature, Organic solvents, Surface, pH, Shear

Consequences of Denaturation:

• Loss of enzymatic activity/Function (death)
• Destruction of toxins
• Improved digestibility
• Loss of solubility
• Changes in texture

Protein denaturation is defined as the partial or complete disorganization of a proteins characteristic three dimensional shape as a result of disruption of its secondary, tertiary, and quarternary structural interactions.

Protein denaturation doesn not affect the primary structure of proteins.

Consequences of Denaturation:

• Loss of enzymatic activity/Function (death)
• Destruction of toxins
• Improved digestibility
• Loss of solubility
• Changes in texture

D i.e. Biological activity is retained

Protein denaturation

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).