Effect of glycosylation on the partition behavior of a human antibody in aqueous two-phase systems.

Human proteins are expressed in some hosts wrongly glycosylated or nonglycosylated. Although it is accepted that glycosylation contributes to the stability of the protein in solution, the effect of glycosylation on the stability of human antibodies is not fully understood. In this work, we present solubility studies of two human antibodies that have the same primary structure but different glycosylation pattern. The studies were done by monitoring the partitioning behavior of both proteins in a series of aqueous two-phase systems at and away the isoelectric point of the proteins and at different temperatures. Our studies show that in the absence of direct electrostatic forces, the partitioning behavior of the antibodies depends on the presence or absence of the polysaccharide chains. Overall, the nonglycosylated protein is less soluble than the glycosylated one. The potential of aqueous two-phase systems for the separation of the glycosylated and nonglycosylated proteins was also explored. A simple series of extractions seems to be enough to separate the glycosylated variety from the nonglycosylated one at high purity but low yields.