Analysis of Lactosylated β-Lactoglobulin by Capillary Electrophoresis

Variously lactosylated species of β-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 β-lactoglobulin, most likely due to their larger molecular size and lower pI. By micellar electrokinetic chromatography using SDS as detergent the lactosylated forms of β-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 β-lactoglobulin. By all methods used, partial separation of at least five forms of β-lactoglobulin were obtained. However, baseline separation of β-lactoglobulin with varying number of lactose units attached was not obtained, probably due to the presence of both variants of β-lactoglobulin with various numbers of lactosyl groups at different sites.