Polypeptide ligands specific for plasma kallikrein

A peptide ligand specific for plasma kallikrein comprising a polypeptide comprising at least three cysteine residues, separated by at least two loop sequences, and a molecular scaffold which forms covalent bonds with the cysteine residues of the polypeptide such that at least two polypeptide loops are formed on the molecular scaffold, wherein the peptide ligand comprises a peptide sequence selected from any of:

• ((06-550) HArg5)
• (SEQ ID NO:
• 56)
• -Ci-S-F-P-Y-[hR]-Cii-V-Y-Y-P-D-I-Ciii-;
• (SEQ ID NO:
• 57)
• -Ci-S-F-[Aze]-Y-R-Cii-V-Y-Y-P-D-I-Ciii;
• ((06-550) Aze3 HArg5)
• (SEQ ID NO:
• 58)
• -Ci-S-F-[Aze]-Y-[hR]-Cii-V-Y-Y-P-D-I-Ciii-;
• ((06-550) NMeArg5)
• (SEQ ID NO:
• 59)
• -Ci-S-F-P-Y-[NMeR]-Cii-V-Y-Y-P-D-I-Ciii-;
• ((06-550) Aze3 NMeArg5)
• (SEQ ID NO:
• 60)
• -Ci-S-F-[Aze]-Y-[NMeR]-Cii-V-Y-Y-P-D-I-Ciii-;
• ((06-259-02 (Sar3-(D-Arg)2)
• (SEQ ID NO:
• 61)
• -Ci-N-T-W-N-P-W-Cii-P-W-D-A-P-L-Ciii-A-Sar3-(D-Arg)2;
• ((06-550)-Sar3-(DArg2))
• (SEQ ID NO:
• 62)
• -Ci-S-F-P-Y-R-Cii-V-Y-Y-P-D-I-Ciii-A-Sar3-(D-Arg)2;
• and
• ((06-550)-Sar3-(DArg2) Aze3 HArg5)
• (SEQ ID NO:
• 63)
• -Ci-S-F-[Aze]-Y-[hR]-Cii-V-Y-Y-P-D-I-Ciii-A-Sar3-
• (D-Arg)2;
• wherein Aze represents an L-azetidine carboxylic acid residue, hR and HArg represents an L-homoarginine residue, NMeR and NMeArg represents an N-α-methyl arginine residue, Sar3 represents 3 sarcosine spacers and (D-Arg)2 represents 2 D-arginine residues.