Patent ID: 7993650

Claim:
A polypeptide having a binding affinity for HER2, wherein the sequence of the polypeptide comprises the sequence of a protein Z, as set forth in SEQ ID NO:1, having from 4 to about 20 substitution mutations thereon, comprising at least four substitution mutations at the positions 13, 14, 28, 32 and 35 of SEQ ID NO:1, wherein the mutations comprise at least three of the following substitution mutations: (a) from phenylalanine to tyrosine at position 13 of SEQ ID NO:1, (b) from tyrosine to tryptophan at position 14 of SEQ ID NO:1, (c) from glutamine to arginine at position 32 of SEQ ID NO:1, and (d) from lysine to tyrosine at position 35 of SEQ ID NO:1.