- Chaotropic agent
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A denaturating agent is a substance which disrupts the three dimensional structure in macromolecules such as proteins, DNA, or RNA and denatures them. A denaturating agent is a chaotropic agent, but chaotropic agents aren't necessarily denaturating agents. Chaotropic agents disrupt the intermolecular forces between water molecules, allowing proteins and other macromolecules to dissolve more easily. Chaotropic agents interfere with stabilizing intramolecular interactions mediated by non-covalent forces such as hydrogen bonds, van der Waals forces, and hydrophobic effects.
Often structural features, as detected by means such as circular dichroism can be titrated in a chaotrope concentration-dependent fashion.
Chaotropic reagents include:
- Urea 6 - 8 mol/l
- Thiourea 2 mol/l
- Guanidinium chloride 6 mol/l
- Lithium perchlorate 4.5 mol/l
High generic salts can have chaotropic properties, by shielding charges and preventing the stabilization of salt bridges. Hydrogen bonding is stronger in nonpolar media, so salts, which increase the chemical polarity of the solvent, can also destabilize hydrogen bonding. Mechanistically this is because there are insufficient water molecules to effectively solvate the ions. This can result in ion-dipole interactions between the salts and hydrogen bonding species which are more favorable than normal hydrogen bonds.
See also
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