African clawed frog
Oviductin (, "oviductal protease") is an enzyme found in the Japanese toad ("Bufo japonicus") and in the African clawed frog ("Xenopus laevis)". Ovulated coelomic egg cells are not fertilisable in these species until they pass through the oviduct, where Oviductin is located. Oviductin catalyses the following chemical reaction in Xenopus laevis: