To obtain RgpA free of adhesin requires a means of separating the RgpA catalytic domain from the adhesins domains or adaptation of a method to prevent RgpA complex association.In this study, recombinant suicide plasmids were designed for use in homologous recombination with the rgpA locus so as to produce modified RgpA that would release from the P. gingivalis surface, thus enabling RgpA purification from the culture fluid.