Patent ID: 7105638

Claim:
A fused polypeptide produced by an organism by expression of a recombinant DNA, said polypeptide comprising a combination of: a first sequence of amino acids comprising a leader sequence, a hinge region, and at least one amino acid defining a cleavage site recognizable and cleavable by a selected enzymatic cleavage agent, said hinge region being a cysteine-free flexible amino acid sequence not normally associated with said leader sequence and comprising at least two amino acids defining a secondary structure which promote cleavage by said cleavage agent at said cleavage site, and a second sequence of amino acids linked to said first sequence defining a selected target polypeptide, whereby said cleavage site is a favored site for cleavage upon treatment of said fused polypeptide with said cleavage agent when said fused polypeptide is disposed in solution and said second amino acid sequence defining said selected target polypeptide is disposed in its three-dimensional conformation said second sequence of amino acids comprising an antigen-binding fragment of an antibody.