denaturant

Denaturant is a substance that disrupts the native structure of biological macromolecules or, in the case of alcohol products, a chemical added to ethanol to render it unfit for human consumption. In biochemistry, denaturants interfere with noncovalent interactions such as hydrogen bonds, ionic contacts, and hydrophobic packing that stabilize folded proteins or nucleic acids, causing denaturation and loss of function.

Common protein denaturants include chaotropic agents such as urea and guanidinium salts (guanidinium chloride, guanidinium thiocyanate) that destabilize hydrophobic cores and hydrogen-bond networks. Detergents such as sodium dodecyl sulfate (SDS) disrupt hydrophobic interactions and can unfold proteins. Other physical or chemical factors—heat, extreme pH, high salt—also promote denaturation. Denaturation can be reversible or irreversible, depending on conditions and the propensity of the unfolded state to aggregate or form new covalent bonds during exposure to the denaturant.

Applications include preparing proteins for purification or analysis, studying folding-unfolding equilibria, and denaturing nucleic acids in certain laboratory procedures (for example to separate strands in sequencing or hybridization assays).

Denatured alcohol is produced by adding denaturants such as methanol, isopropanol, or acetone, sometimes with bittering agents, to ethanol to prevent beverage use and to reduce taxation. Regulations typically specify acceptable denaturants and concentrations.

Safety and regulatory notes: Denaturants are often toxic or hazardous; handling requires appropriate procedures. The term denaturant therefore covers both laboratory reagents and consumer-avoidance additives, depending on context.