Editing Chaotropic agent (section)

{{Short description|Molecules that disrupt hydrogen bonding}}
A '''chaotropic agent''' is a molecule in water solution that can disrupt the [[hydrogen bonding]] network between water molecules (i.e. exerts [[chaotropic activity]]). This has an effect on the stability of the [[native state]] of other molecules in the solution, mainly [[macromolecules]] ([[protein]]s, [[nucleic acid]]s) by weakening the [[hydrophobic effect]]. For example, a chaotropic agent reduces the amount of order in the structure of a [[protein]] formed by water molecules, both in the bulk and the hydration shells around [[hydrophobic]] [[amino acids]], and may cause its [[denaturation (biochemistry)|denaturation]].

Conversely, an '''antichaotropic agent''' ([[kosmotropic]]) is a molecule in an aqueous solution that will increase the hydrophobic effects within the solution.<ref name=Moelbert>{{cite journal |last1=Moelbert |first1=S |last2=Normand |first2=B |last3=De Los Rios |first3=P |title=Kosmotropes and chaotropes: modelling preferential exclusion, binding and aggregate stability |journal= Biophysical Chemistry |volume=112 |issue=1 |year=2004 |pages=45–57 |doi=10.1016/j.bpc.2004.06.012|pmid=15501575 |arxiv=cond-mat/0305204 |s2cid=9870865 }}</ref> Antichaotropic salts such as [[ammonium sulphate]] can be used to precipitate substances from the impure mixture. This is used in protein purification processes, to remove undesired proteins from solution.