Cysteine proteinase with a strong preference for substrates with Lys in the P1 position. Hydrolyzes bovine hemoglobin, bovine serum albumin, casein, human placental type I collagen and human IgA and IgG. Disrupts the functions of polymorphonuclear leukocytes. May act as a virulence factor in the development of peridontal disease. Involved in the coaggregation of P.gingivalis with other oral bacteria. Endopeptidase with strict specificity for lysyl bonds. Activated by the thiol-reducing agents cysteine, 2-mercaptoethanol and dithiothreitol. Inhibited by idoacetamide, idoacetic acid, leupeptin, tosyl-L-lysine and tosyl-L-phenylalanine. Not inhibited by elastatinal, chymostatin, cystatins, alpha1-antichymotrypsin or the serine protease inhibitors phenylmethylsulfonyl fluoride and diisopropylfluorophosphate. Not inhibited by metal ion chelators. Inhibited by the heavy metal ions Fe(3+), Zn(2+), Cu(2+) and Mn(2+). Optimum pH is 7.5. Activity remains high from pH 6.5 to 9.5. Loses 60% of its activity following incubation at pH 3.5 for 5 minutes. Only retains 40% of activity after incubation at 60 degrees Celsius for 10 minutes. Proteolytically cleaved into a catalytic subunit and three adhesins. Arg-gingipain is involved in this post-translational processing (By similarity). Several forms of kgp with differences at the C-terminus exist in different P.gingivalis strains. Belongs to the peptidase C25 family.