Inhibition of coaggregation between Porphyromonas gingivalis and Streptococcus oralis by fibrinogen fragments Free

The localization of regions of fibrinogen that inhibit coaggregation between Porphyromonas gingivalis and Streptococcus oralis was investigated. The coagregation was inhibited by Aα and γ chains, but not by Bβ chain. The inhibitory activity of fragment D was more potent than that of fragment E. Some cyanogen bromide-treated fragments isolated from Aα and γ chains including the NH₂-terminal 148–207 amino acids residues of Aα chain (Aα 148–207) and γ1–78 showed inhibitory activities. Aα148–207 was further digested with lysyl endopeptidase. Aα158–206 which contained four and two arginine residues, respectively, retained the inhibitory activities. When the arginine residues of these two peptides were modified by phenylglyoxal, the inhibitory activities were much reduced. These findings suggest that the arginine residues of some specific regions of fibrinogen may play an important role in the inhibition of the coaggregation.