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 (By similarity). Endopeptidase with strict specificity for lysyl bonds. Proteolytically cleaved into a catalytic subunit and three adhesins. Arg-gingipain is involved in this post-translational processing. Several forms of kgp with differences at the C-terminus exist in different P.gingivalis strains. Belongs to the peptidase C25 family.