Abstract: Methods are provided for the synthesis of polymer conjugates of cytokines, chemokines, growth factors, polypeptide hormones and receptor-binding antagonists thereof, which conjugates retain unusually high receptor-binding activity. Preparation of polymer conjugates according to the methods of the present invention diminishes or avoids steric inhibition of receptor-ligand interactions that commonly results from the attachment of polymers to receptor-binding regions of cytokines, chemokines, growth factors and polypeptide hormones, as well as to agonistic and antagonistic analogs thereof. The invention also provides conjugates and compositions produced by such methods. The conjugates of the present invention retain a higher level of receptor-binding activity than those produced by traditional polymer coupling methods that are not targeted to avoid receptor-binding domains of cytokines, chemokines, growth factors and polypeptide hormones.

Abstract: A naturally occurring or recombinant protein, especially a mutein of porcine urate oxidase (uricase), that is essentially free of large aggregates can be rendered substantially non-immunogenic by conjugation with a sufficiently small number of strands of polymer such that the bioactivity of the protein is essentially retained in the conjugate. Such conjugates are unusually well suited for treatment of chronic conditions because they are less likely to induce the formation of antibodies and/or accelerated clearance than are similar conjugates prepared from protein preparations containing traces of large aggregates.

Abstract: A naturally occurring or recombinant urate oxidase (uricase) covalently coupled to poly(ethylene glycol) or poly(ethylene oxide) (both referred to as PEG), wherein an average of 2 to 10 strands of PEG are conjugated to each uricase subunit and the PEG has an average molecular weight between about 5 kDa and 100 kDa. The resulting PEG-uricase conjugates are substantially non-immunogenic and retain at least 75% of the uricolytic activity of the unmodified enzyme.

Abstract: A naturally occurring or recombinant protein, especially a mutein of porcine urate oxidase (uricase), that is essentially free of large aggregates can be rendered substantially non-immunogenic by conjugation with a sufficiently small number of strands of polymer such that the bioactivity of the protein is essentially retained in the conjugate. Such conjugates are unusually well suited for treatment of chronic conditions because they are less likely to induce the formation of antibodies and/or accelerated clearance than are similar conjugates prepared from protein preparations containing traces of large aggregates.

Abstract: A biologically persistent, water-soluble, substantially non-immunogenic, substantially non-antigenic conjugate of superoxide dismutase is prepared by coupling one to five strands of a polyalkylene glycol which is polyethylene glycol or polyethylene-polypropylene glycol copolymer, wherein said polyalkylene glycol has an average molecular weight of about 35,000-1,000,000.

Abstract: A biologically persistent, water-soluble, substantially non-immunogenic, substantially non-antigenic conjugate of superoxide dismutase is prepared by coupling one to five strands of a polyalkylene glycol which is polyethylene glycol or polyethylene-polypropylene glycol copolymer, wherein said polyalkylene glycol has an average molecular weight of about 35,000-1,000,000.

Abstract: A biologically persistent, water-soluble, substantially non-immunogenic, substantially non-antigenic conjugate of superoxide dismutase is prepared by coupling one to five strands of a polyalkylene glycol which is polyethylene glycol or polyethylene-polypropylene glycol copolymer, wherein said polyalkylene glycol has an average molecular weight of about 35,000-1,000,000.

Abstract: A biologically persistent, water-soluble, substantially non-immunogenic, substantially non-antigenic conjugate of superoxide dismutase is prepared by coupling one to five strands of a polyalkylene glycol which is polyethylene glycol or polyethylene-polypropylene glycol copolymer, wherein said polyalkylene glycol has an average molecular weight of about 35,000-1,000,000.