Envelysin (EC 3.4.24.12, sea-urchin-hatching proteinase, hatching enzyme, chorionase, chorion-digesting proteinase, chymostrypsin, sea urchin embryo hatching enzyme) is an enzyme. This enzyme catalyses the following chemical reaction Envelysin (EC 3.4.24.12, sea-urchin-hatching proteinase, hatching enzyme, chorionase, chorion-digesting proteinase, chymostrypsin, sea urchin embryo hatching enzyme) is an enzyme. This enzyme catalyses the following chemical reaction This enzyme is a glycoprotein from various members of the class Echinoidea.