Preparation of Soluble Proteins from Escherichia coli

Abstract

Purification of human IL‐1β is used in this unit as an example of the preparation of soluble proteins from E. coli . Bacteria containing IL‐1β are lysed, and IL‐1 β in the resulting supernatant is purified by anion‐exchange chromatography, salt precipitation and cation‐exchange chromatography, and then concentrated. Finally, the IL‐1 β protein is applied to a gel‐filtration column to separate it from remaining higher‐ and lower‐molecular‐weight contaminants, the purified protein is stored frozen or is lyophilized. The purification protocol described is typical for a protein that is expressed in fairly high abundance (i.e., >5% total protein) and accumulates in a soluble state.