Histolysain (EC 3.4.22.35, histolysin, Entamoeba histolytica cysteine proteinase, amebapain, Entamoeba histolytica cysteine protease, Entamoeba histolytica neutral thiol proteinase) is an enzyme. This enzyme catalyses the following chemical reaction Histolysain (EC 3.4.22.35, histolysin, Entamoeba histolytica cysteine proteinase, amebapain, Entamoeba histolytica cysteine protease, Entamoeba histolytica neutral thiol proteinase) is an enzyme. This enzyme catalyses the following chemical reaction This enzyme is present in the protozoan, Entamoeba histolytica.