Patent ID: 7625564

Claim:
An isolated fusion protein having a prolonged half-life in vivo in comparison to naturally occurring or recombinant native human erythropoietin comprising: (a) a naturally occurring human erythropoietin molecule having a cysteine residue proximate to a C terminal thereof; and (b) a human IgG Fc fragment comprising a hinge region, wherein an N terminal of said hinge region is directly linked to said C terminal of said erythropoietin molecule and wherein said hinge region is naturally occurring except for a mutation at amino acid position 6, measured from said N terminal, replacing a cysteine residue with a non-cysteine residue, whereby the first cysteine residue of said hinge region located nearest said N terminal is spaced at least 17 amino acids apart from said cysteine residue of said erythropoietin molecule, wherein said protein has the amino acid sequence present in SEQ ID NO: 2 or a sequence having at least 98% sequence identity thereto, said protein having a non-cysteine amino acid residue at residue 172.