CHARACTERIZATION OF PROTEINS SEPARATED BY DISPLACEMENT CHROMATOGRAPHYUSING LOW-ANGLE LASER-LIGHT SCATTERING PHOTOMETRY

Beta-lactoglobulin A and B (beta-LACT) were separated by displacement chromatography (DSC) on an ion-exchange column using dextran sulfate a s the displacer. A LALLS photometer and a UV detector, in series, were used to determine the molecular weight (MW) of the proteins, on-line. The results indicate that both, beta-LACT A and B, were present as di mers in the buffer used for the mobile phase. The MWs of the proteins were about 6-8 % higher than the theoretical MW of a dimer (approximat ely 37,000). Additional control studies have shown the presence of a h igh molecular weight species in both the proteins, which could possibl y be an aggregate. This species was observed in the LALLS signal but w as nearly absent in the UV signal. Our work has demonstrated the feasi bility of interfacing LALLS with displacement chromatography for detec ting impurities or aggregates which may be difficult to detect by conv entional detectors used for chromatography.