Large‐scale fractionation of proteins by isoelectric focusing in a multi‐compartment electrolysis apparatus

Abstract A preparative electrolysis apparatus for isoelectric focusing of large amounts of proteins is described. It contains 46 separation compartments, and its total volume is about 7.6 liters. The compartments are closed, and internal cooling and stirring are effected by slow rotation of the whole apparatus in a tank filled with cold water. The apparatus can be run with an electric load of up to 5 kW, and an isoelectric focusing takes 2–3 days. It has been shown that crude pepsin can be purified in this apparatus. Preparations of hemoglobin and bovine whey have also been run in the apparatus. Fourteen grams of whey protein has been completely separated into its main components, serum albumin (pI 4.60), α‐lactalbumin (pI 5.01), and β‐lactoglobulin (pI 5.13–5.23), whereas the latter component was partially separated into its subcomponents A and B.