Purification of ovalbumin and lysozyme from a commercial product by recycling isotachophoresis.

The aim of this work was to test the suitability of using recycling isotachophoresis (RITP) for the purification of ovalbumin (OVA) and/or lysozyme (LYSO) from a commercial OVA product containing LYSO and conalbumin (CAL) as major proteinaceous impurities. The search for suitable electrolyte systems and spacers was carried out by capillary isotachophoresis. RITP was performed in a recycling free-flow focusing apparatus in the batch mode with immobilization of the advancing zone structure via a controlled counterflow. Typically 700 mg of the commercial product were processed within 2 h. Enhancement of the sample load was achieved by a feed of sample under counterflow control. The collected fractions were analysed separately for conductivity, pH and ultraviolet absorption, and selected fractions were characterized by analytical capillary electrophoretic methods. All three proteins could be separated and fractionated using suitable spacers. Depending on the chosen conditions either OVA or LYSO could be purified in amounts larger than milligrams per hour (OVA 300 mg/h; LYSO 10 mg/h). The instability of CAL in solution prevented its isolation in the investigated configurations.