A proteolytically active polypeptide comprising an acid sequence having at least 50% sequence identity with the sequence of SEQ ID NO: 1 with the proviso that the polypeptide does not comprise the amino acid sequence of SEQ ID NO: 1. A nucleic acid encoding the polypeptide. An antibody specifically binding to the polypeptide. A method for the manufacture of a proteolytically processed polypeptide comprising contacting a first polypeptide having at least 50% sequence identity to SEQ ID NO: 1 with a second polypeptide that is susceptible to proteolysis by said first polypeptide.