Analysis of lactosylated β-lactoglobulin by capillary electrophoresis

Variously lactosylated species of beta-lactoglobulin AB were analysed by capillary electrophoresis at low pH and high pH with and without buffer additives. By simple capillary zone electrophoresis at either low or high pH the lactosylated forms had longer migration times than the native beta-lactoglobulin, most likely due to their larger molecular size and lower pI. By micellar electrokinetic chromatography using SDS as detergent the lactosylated forms of beta-lactoglobulin had shorter migration times than the native species, due to less interaction with the micelles. The methods used were also able to distinguish between more or less lactosylated forms of beta-lactoglobulin. By all methods used, partial separation of at least five forms of beta-lactoglobulin were obtained. However, baseline separation of beta-lactoglobulin with varying number of lactose units attached was not obtained, probably due to the presence of both variants of beta-lactoglobulin with various numbers of lactosyl groups at different sites. (C) 1999 Elsevier Science Ltd. All rights reserved.