Protein crystal regulation and harvest via electric field-based method

Electric field is a critical issue for the migration and assembly of molecules during protein crystallization. This article covers the effects of external and internal electric field on the regulation and harvest of high-quality protein crystals. Emphasis is placed on contributions from electric fields strength, direction, frequency, and distribution, aiming to improve the crystal quality, such as crystal size, number, and diffraction. In addition, the application of electric field is beneficial as it reveals the solution fluctuation, crystal nucleation, and crystal growth mechanisms due to the migration of protein molecules towards one electrode side with opposite charge, which was facilely observed by an on-line camera. The motion of high-density solution cluster and micro-crystal driven by electric field extends the supersaturated regions suitable for crystal construction, thus altering the crystallization phase diagram. Lastly, we review the promising developments on further crystallization mechanism revelation and novel electric field-induced protein crystallization such as the synergy of electric field and typical crystallizers.