A peptide selected from to as follows: a peptide consisting of (a) a peptide consisting of the amino acid residues No. 1 to No. 10 from the N-terminal of SEQ ID NO:1 and (b) a peptide selected from peptides consisting of the amino acid residues No. 28 to No. 36, No. 28 to No. 37, No. 28 to No. 38, No. 28 to No. 39, No. 28 to No. 40, No. 28 to No. 41, No. 28 to No. 42 from the N-terminal of SEQ ID NO:1, the peptide (a) and the peptide (b) being bound to each other, wherein cysteine or a cysteine analogue is bound to the C-terminal of the resulting combination of the peptide (a) and the peptide (b); a peptide consisting of (a) a peptide consisting of the amino acid residues No. 2 to No. 10,, No. 2 to No. 9, from the N-terminal of SEQ ID NO:1 and (b) a peptide consisting of the amino acid residues No. 28 to No. 37 from the N-terminal of SEQ ID NO:1, the peptide (a) and the peptide (b) being bound to each other, wherein cysteine or a cysteine analogue is bound to the C-terminal of the resulting combination of the peptide (a) and the peptide (b); a peptide consisting of (a) a peptide consisting of the amino acid residues No. 1 to No. 18 from the N-terminal of SEQ ID NO: 1 and (b) a peptide consisting of the amino acid residues No. 28 to No. 42 from the N-terminal of SEQ ID NO:1, the peptide (a) and the peptide (b) being bound to each other, wherein cysteine or a cysteine analogue is bound to the C-terminal of the resulting combination of the peptide (a) and the peptide (b); a peptide consisting of the amino acid residues No. 1 to 26 from the N-terminal of SEQ ID NO:1 wherein cysteine or a cysteine analogue is inserted between the amino acid residues Nos. 18 and 19 from the N-terminal; a peptide consisting of the amino acid residues No. 1 to No. 28 from the N-terminal of SEQ ID NO:1, wherein cysteine or a cysteine analogue is inserted between the amino acid residues Nos. 18 and 19 from the N-terminal, and wherein cysteine or a cysteine analogue is bound to the C-terminal of said peptide; a peptide consisting of the amino acid residues No. 1 to No. 18 from the N-terminal of SEQ ID NO:1 to the C-terminal of which cysteine or a cysteine analogue is bound, to which a peptide consisting of the amino acid residues No. 28 to No. 37 from the N-terminal of SEQ ID NO:1 is further bound; a peptide consisting of the amino acid residues No. 1 to No. 28 from the N-terminal of SEQ ID NO:1, to the C-terminal of which a cysteine analogue is bound; a peptide consisting of two of a peptide consisting of the amino acid residues No. 1 to No. 28 from the N-terminal of SEQ ID NO:1, to the C-terminal of which cysteine or a cysteine analogue is bound, said two of the peptides being bound to each other via a disulfide bond between said cysteines or said cysteine analogues. a peptide consisting of (a) a peptide consisting of the amino acid residues No. 1 to No. 10 from the N-terminal of SEQ ID NO:1 and (b) a peptide selected from peptides consisting of the amino acid residues No. 28 to No. 36, No. 28 to No. 37, No. 28 to No. 38, No. 28 to No. 39, No. 28 to No. 40, No. 28 to No. 41, No. 28 to No. 42 from the N-terminal of SEQ ID NO:1, the peptide (a) and the peptide (b) being bound to each other, wherein cysteine or a cysteine analogue is bound to the C-terminal of the resulting combination of the peptide (a) and the peptide (b); a peptide consisting of (a) a peptide consisting of the amino acid residues No. 2 to No. 10,, No. 2 to No. 9, from the N-terminal of SEQ ID NO:1 and (b) a peptide consisting of the amino acid residues No. 28 to No. 37 from the N-terminal of SEQ ID NO:1, the peptide (a) and the peptide (b) being bound to each other, wherein cysteine or a cysteine analogue is bound to the C-terminal of the resulting combination of the peptide (a) and the peptide (b); a peptide consisting of (a) a peptide consisting of the amino acid residues No. 1 to No. 18 from the N-terminal of SEQ ID NO: 1 and (b) a peptide consisting of the amino acid residues No. 28 to No. 42 from the N-terminal of SEQ ID NO:1, the peptide (a) and the peptide (b) being bound to each other, wherein cysteine or a cysteine analogue is bound to the C-terminal of the resulting combination of the peptide (a) and the peptide (b); a peptide consisting of the amino acid residues No. 1 to 26 from the N-terminal of SEQ ID NO:1 wherein cysteine or a cysteine analogue is inserted between the amino acid residues Nos. 18 and 19 from the N-terminal; a peptide consisting of the amino acid residues No. 1 to No. 28 from the N-terminal of SEQ ID NO:1, wherein cysteine or a cysteine analogue is inserted between the amino acid residues Nos. 18 and 19 from the N-terminal, and wherein cysteine or a cysteine analogue is bound to the C-terminal of said peptide; a peptide consisting of the amino acid residues No. 1 to No. 18 from the N-terminal of SEQ ID NO:1 to the C-terminal of which cysteine or a cysteine analogue is bound, to which a peptide consisting of the amino acid residues No. 28 to No. 37 from the N-terminal of SEQ ID NO:1 is further bound; a peptide consisting of the amino acid residues No. 1 to No. 28 from the N-terminal of SEQ ID NO:1, to the C-terminal of which a cysteine analogue is bound; a peptide consisting of two of a peptide consisting of the amino acid residues No. 1 to No. 28 from the N-terminal of SEQ ID NO:1, to the C-terminal of which cysteine or a cysteine analogue is bound, said two of the peptides being bound to each other via a disulfide bond between said cysteines or said cysteine analogues.