1. An isolated zymogen-activating peptide (ZAP) containing the amino acid sequence XX-X-X-X-B (SEQ ID NO: 2), where Χ denotes a large hydrophobic amino acid, denotes a large hydrophobic amino acid or aromatic amino acid, denotes G, D, Ε, Ν, Q, D-Gly, D-Asp, D-Glu, D-Asn or D-Gln, X is G or A, B is any amino acid, and n is a number from 0 to 46.2. The isolated ZAP of claim 1, wherein M, L, I, V or norleucine (SEQ ID NO: 4). The isolated ZAP of claim 2, wherein Χ means L, I or V (SEQ ID NO: 5). 4. The isolated ZAP according to claim 3, in which means I (SEQ ID NO: 7). 5. Isolated ZAP according to any one of paragraphs. 1-4, in which means M, L, I, V, norleucine, F or Y (SEQ ID NO: 8) .6. The isolated ZAP of claim 5, wherein X is I, V, L, or F (SEQ ID NO: 9). 7. The isolated ZAP of claim 6, wherein X is I or V (SEQ ID NO: 10). Isolated ZAP according to any one of paragraphs. 1-4, 6-7, in which means G, D or N (SEQ IDNO: 11) .9. The isolated ZAP of claim 8, wherein X is G, (SEQ ID NO: 12). 10. Isolated ZAP according to any one of paragraphs. 1-4, 6-7, 9, in which X is G (SEQ IDNO: 13) .11. Isolated ZAP according to any one of paragraphs. 1-4, 6-7, 9, in which X-X-X-X (SEQ ID NO: 14) means IVGG (SEQ ID NO: 15), IVDG (SEQ ID NO: 16), IVdG, IVGG (SEQ ID NO: 17), IIGG (SEQ ID NO: 18), VVNG (SEQ ID NO: 19), VVGG (SEQ ID NO: 20), IVGG (SEQ ID NO: 21), LIDG (SEQ ID NO: 22) , IVEG (SEQ ID NO: 23), ITGG (SEQ ID NO: 24), IVNG (SEQ ID NO: 25), IFNG (SEQ ID NO: 26), IYGG (SEQ ID NO: 27), ILGG (SEQ ID NO: 28) or IKGG (SEQ ID NO: 29), and where d is D-aspartic acid. 12. Isolated ZAP according to any one of paragraphs. 1-4, 6-7, 9, in which ZAP specifically binds a polypeptide containing a serine protease domain or a domain similar to a serine protease and activates a polypeptide containing a zymogen domain of a serine protease or a zymogen domain similar to a zymogen of a serine protease. 13. The isolated ZAP of claim 12, wherein the ZAP specifically binds to the β-domain of the pro1
