FIG 1.

Alignment of deduced amino acid sequences of DPP4 from P. gingivalis (Pg; PGN_1469), T. forsythia (Tf; BFO_1659), and P. intermedia (Pi; GenBank accession number AB127116). Hyphens represent gaps introduced for maximal matching. Common amino acid residues are marked with asterisks, and those matched between two DPPs are indicated by dots. Potential sets of three residues (Ser⁵⁹³, Asp⁶⁶⁸, and His⁷⁰⁰ in PgDPP4), forming the essential triad of serine peptidases, are indicated in red. The conserved N-terminal motif with two adjacent essential Glu residues (Glu¹⁹⁵and Glu¹⁹⁶ in blue) is boxed.