Characterization of Porphyromonas (bacteroides) gingivalis hemagglutinin as a protease.

A hemagglutinin (HA) was purified to homogeneity from the membrane fraction of the oral bacterium Porphyromonas gingivalis. The HA possessed protease activity hydrolyzing proteins and arginine-containing synthetic substrates. The protease activity was inhibited by thiol-blocking reagents, and hence the HA can be characterized as a cystein protease. The HA functions as an attachment factor and its substrate-binding site is responsible for the attachment to an erythrocyte.