Renaturation of dextranase activity from culture supernatant fluids of Streptococcus sobrinus after sodium dodecylsulfate polyacrylamide gel electrophoresis.

A rapid and reproducible method for the assay of individual fractions of the multicomponent dextranase activity of Streptococcus sobrinus after reduction/denaturation and electrophoresis in acrylamide gels is described. Multiple forms of dextranase, possible virulence factors in the formation of dental caries by oral Streptococci (S. mutans, S. sobrinus, S. sanguis, S. cricetus, and S. rattus), have been separated in sodium dodecylsulfate-polyacrylamide gels into which an indicator substrate, blue dextran, has been incorporated, and identified after renaturation to remove the reducing/denaturing agents of the Laemmli buffer system.