precipitation protein precipitation CHMO:0002466 https://orcid.org/0000-0001-5985-7429 2009-09-28T11:55:08Z The sedimentation of a solid protein (a 'precipitate') from an aqueous solution caused by the addition of an organic solvent (e.g. methanol), a polyelectrolyte (e.g. alginate) or a salt (e.g. ammonium sulfate) in a process known as 'salting out'.