Patent ID: 8008453

Claim:
A composition of matter of the formula wherein: F 1 is a monomer of the monomeric or multimeric Fc domain; X 1 is covalently bound to the N-terminus of F 1 through the α-amino site of F 1 ; X 2 is covalently bound to the C-terminus of F 1 through the α-carboxy site of F 1 ; X 3 is covalently bound to the one or more specifically selected internal conjugation site(s) in F 1 through the side chain of a cysteine residue added to the Fc domain by substitution at an Fc site selected from the group consisting of Leu139, Gln143, Ser145, and Ser196, relative to reference sequence SEQ ID NO:599, or, if g>1, any combination of these members; X 1 , X 2 , and X 3 are each independently selected from -(L 1 ) c -P 0 , -(L 1 ) c -P 1 -(L 2 ) d -P 2 , -(L 1 ) c -P 1 -(L 2 ) d -P 2 -(L 3 ) e -P 3 , and -(L 1 ) c -P 1 -(L 2 ) d -P 2 -(L 3 ) e -P 3 -(L 4 ) f -P 4 ; P 0 , P 1 , P 2 , P 3 , and P 4 are each independently selected from the group consisting of: i) a pharmaceutically acceptable polymer or dextran; ii) a pharmacologically active polypeptide, peptide, peptidomimetic, or non-peptide organic moiety; iii) a radioisotope, an enzyme, a biotinyl moiety, a fluorophore, or a chromophore; and iv) an immobilized substrate, provided that in a chain comprising more than one additional functional moieties, the immobilized substrate is the moiety most distal from F 1 , and there can be no more than one immobilized substrate in the chain; L 1 , L 2 , L 3 , and L 4 are each independently linkers; a, b, c, d, e, and f are each independently 0 or 1; and g is 1, 2, 3, or 4.