Denaturation of proteins

Denaturation is the process by which a protein's carefully folded, specific three-dimensional shape is disrupted and destroyed by an external physical or chemical stress -- commonly high temperature, exposure to acid or base (i.e. a significant pH change from the protein's normal physiological environment), or even mechanical agitation (vigorous shaking or whipping). What denaturation specifically disrupts are the NON-COVALENT interactions responsible for holding the protein's secondary, tertiary or quaternary structure together -- the hydrogen bonds, electrostatic attractions, dipole-dipole attractions and dispersion forces described in sections 14.3.4b-d. Denaturation does NOT break the covalent peptide (amide) bonds that hold the primary structure -- the actual sequence of amino-acid residues -- together; the amino-acid sequence itself survives denaturation completely intact, even though the protein's overall folded shape does not. Because so much of a protein's biological function depends specifically on its correctly-folded three-dimensional shape (recall, for instance, how an enzyme's active site or haemoglobin's four-subunit assembly must have exactly the right geometry to work), disrupting the secondary/tertiary/quaternary structure through denaturation very often results in a substantial change in the protein's physical properties (a classic example being loss of water-solubility, since denaturation typically exposes a globular protein's pr …