Patent ID: 8617894

Claim:
A method of constructing a protein scaffold library, comprising the steps of: providing an isolated protein scaffold based on a fibronectin type III (FN3) domain, the isolated protein scaffold comprising: a backbone portion comprising the amino acid sequence of residues 1-21, 29-74, and 82-89 of SEQ ID NO:16; a B:C loop portion between the backbone portion residues corresponding to residues 21 and 29 of SEQ ID NO: 16, wherein the B:C loop portion has an amino acid sequence that has at least 75% identity to the amino acid sequence of SEQ ID NOs: 22, 23, 36, 41, 42, 44, 45, 52, 58, 63, or 64; and an F:G loop portion between the backbone portion residues corresponding to residues 74 and 82 of SEQ ID NO: 16, wherein the F:G loop portion has an amino acid sequence that has at least 75% identity to the amino acid sequence of SEQ ID NOs: 78, 80, 96, 97, 112, 114, 122, 127, 145, 157, or 167; and introducing mutations into copies of the isolated protein scaffold to form the protein scaffold library.