T-kininogen and a 45 kda proteinase from Porphyromonas gingivalis

To clarify the pathogenic role of proteinases from Porphyromonas gingivalis, a 45 kDa proteinase was isolated from P. gingivalis culture medium by a combination of gel filtration (Bio-Gel A-0.5 m) and ion-exchange chromatographies (DEAE-Sephacel and SP-Sepharose FF). The enzyme was found to have a molecular mass of 45 kDa by SDS-PAGE and to require mercaptoethanol for its activation. The 45 kDa proteinase cleaved T-kininogen into small fragments, but failed to release kinin. In contrast, T-kininogen inhibited the Arg-amidolytic activity of the 45 kDa proteinase with a Ki of 2 nM. On the other hand, the 45 kDa proteinase did not stimulate the production of PGE2, IL-1beta, and TNF-alpha from the macrophages.