Using the dextran-binding domain (DBD) of a type of glucosyltransferase (GTF) from Streptococcus sobrinus, we have developed a novel method for purifying recombinant proteins. DBD-tagged green and red fluorescent proteins as well as the parent GTF and DBD moiety were adsorbed well to commercially available cross-linked dextran (such as Sephadex beads and Sephacryl beads), and eluted efficiently with water-soluble dextran. The purity of the eluted proteins after this one-step affinity purification was ∼90% or better. The results suggest that DBD can be used as a powerful carrier for purification of various recombinant proteins.
