3.4.21.99	hydrolyses arginyl bonds, preferably with Pro in the P2 position	the enzyme from the ascidian -Prochordate- Halocynthia roretzi is localised in the sperm head, and released during sperm activation. A proline-rich region is involved in binding to the vitelline coat of the egg. Belongs in peptidase family S1, trypsin family	-