Patent ID: 7960140

Claim:
A dual-chain avidin (dcAvd) comprising a fusion of two circularly permuted avidin monomers (cpAvd), the avidin monomers selected from the group consisting of: circularly permuted avidin monomer comprising a new N-terminus that is before β-strand 5 and a new C-terminus that is after β-strand 4 (cpAvd5→4); circularly permuted avidin monomer comprising a new N-terminus that is before β-strand 6 and a new C-terminus that is after β-strand 5 (cpAvd6→5); and circularly permuted avidin monomer comprising a new N-terminus that is before β-strand 4 and a new C-terminus that is after β-strand 3 (cpAvd4→3), wherein in the cpAvd, the original C-terminal amino acid and the original N-terminal amino acid are joined directly or via a linker, thus creating the new C-terminus and the new N-terminus, and the dual-chain avidin binds biotin or other ligand.