Comparative studies of three proteases of Porphyromonas gingivalis

Three thiol-activated proteases, designated Qa, Ra, and Sa, in the soluble fraction of the cell extract of Porphyromonas gingivalis ATCC 33277 were purified by combinations of gel filtration, ion exchange chromatography and electrophoresis, and characterized. The molecular weights estimated by gel filtration method were 43 kDa (Sa), 87 kDa (Ra), and 170 kDa (Qa). However, they were found to have the same molecular weight (43 kDa), when estimated by SDS-PAGE, indicating that Sa is a monomeric, Ra is a dimeric and Qa is a tetrameric form. The 3 enzymes showed quite similar biochemical properties, and they could degrade not only the synthetic substrates but immunoglobulins, fibrinogen and albumin.