Purification, and comparison, of two forms of dextransucrase from Streptococcus sanguis

A procedure has been developed whereby native and proteolyzed forms of dextransucrase have been purified; it involves gel filtration, and hydroxylapatite chromatography in the presence of 0.10% sodium dodecyl sulfate. This procedure is highly reproducible, and permits approximately 30% recovery of high purity (94% homogeneous) enzyme as an inactive, SDS complex that can be reactivated by the addition of Triton X-100. The purified enzymes have been compared with regard to amino acid compositions, and isoelectric and catalytic properties. An analysis of the structure of their product D-glucans was also made. Although the structural characteristics of the enzyme forms differ, proteolysis does not cause alterations in their catalytic properties.