Preparation of protein conjugates with alkoxypolyethylene glycols

Alkoxypolyethylene glycols can be converted to O-alkoxypolyethyleneglycoxy-S-carboxamidomethyldithiocarbonates. These dithiocarbonates are useful for the preparation of protein conjugates with alkoxypolyethylene glycols. Studies with model compounds suggest that sites of reaction are primarily the amino groups of proteins and, to a lesser extent, the aliphatic and phenolic hydroxyl groups. Antigen E, which is an allergenic protein from ragweed pollen, was modified with different alkoxypolyethylene glycols by the above procedure. The size and the hydrophobicity of alkoxypolyethylene glycols used were found to influence the reduction in antigenic activity of conjugates.