Alteration of immunological properties of bovine serum albumin by covalent attachment of polyethylene glycol.

TLDR

Methoxypolyethylene glycols (1900–5000 Da) were covalently conjugated to bovine serum albumin via cyanuric chloride, and the resulting PEGylated proteins were iodinated or radiolabeled for intravenous injection in rabbits. PEGylated bovine serum albumin lost immunogenicity, eliciting no antibodies against itself or native BSA, maintained a circulation half‑life comparable to unmodified protein, was not cleared by antibody formation, and showed altered solubility, electrophoretic mobility, ion‑exchange behavior, and sedimentation, with both 125I and 14C labels appearing almost quantitatively in urine after 30 days.

Abstract

Methoxypolyethylene glycols of 1900 and 5000 daltons have been attached covalently to bovine serum albumin using cyanuric chloride as the coupling agent. When sufficient polymer is attached, the modified bovine serum albumin appears to lose its immunogenicity in the rabbit and, on intramuscular or intravenous injection, elicits antibodies neither to itself nor to native bovine serum albumin. It does not react with antibodies raised against native bovine serum albumin. Bovine serum albumin to which methoxypolyethylene glycol has been attached exhibits a blood circulating life in the rabbit rather similar to native bovine serum albumin, except that it is not removed from circulation by the eventual development of antibodies. Modified bovine serum albumins which had been iodinated with 125I, or prepared with [14C]cyanuric chloride, were injected intravenously in rabbits. Both labels appeared almost quantitatively in the urine after 30 days. The modified bovine serum albumins showed substantial changes in properties, such as solubility, electrophoretic mobility in acrylamide gel, ion exchange chromatography, and sedimentation, as compared with the unmodified protein.