PURIFICATION OF a-LACTALBUMIN AND b-LACTOGLOBULIN FROM WHEY PROTEIN ISOLATE USING TWO-STAGE ULTRAFILTRATION SYSTEMS

摘要

Recent studies have demonstrated that membrane ultrafiltration can be used to separate proteins with very similar size, but these investigations have been performed with model binary mixtures. This study examined the use of a two-stage tangential flow filtration system for the purification of both -LA and -LG from whey protein isolate. Separation was achieved using 100-kD and 30-kD membranes in series, with the buffer concentration and filtration velocity for each stage adjusted to give optimal separation. Two purification strategies were examined: one using the 100-kD membrane followed by the 30-kD and one with the reverse order. In both cases, the -LA purification was greater than 10-fold at 90 % yield. The recovery of -LG was more challenging since it was obtained in the permeate from one stage and the retentate from the other. The results provide important insights into the development of staged membrane systems for the purification of complex protein mixtures.