Ion exchange chromatography, one of the major procedures for protein purification, seldom provides single-step purification due to a lack of specific affinity. In this work, a novel and simple method called “back flush” (i.e., reversing the flow direction of elution relative to that of sample loading) was developed to achieve single-step purification on an ion exchanger. Tips for the conditions and operation by back flush are presented. Our study demonstrates, for the first time, the feasibility and dramatic improvement for protein purification by the back-flush method.
