Immunoadsorbents: non-specific binding of proteins to albumin-sepharose

Human serum albumin-Sepharose was prepared by coupling human serum albumin to cyanogen bromide activated Sepharose 4B. This immunoadsorbent showed considerable non-specific protein adsorption. The adsorbed proteins were mainly immunoglobulins which could not be separated from required antibody. It is suggested that basic groups formed in the preparation of the albumin-Sepharose are responsible for this non-specific protein adsorption. Non-specific protein adsorption could be completely eliminated by neutralizing the basic groups of the albumin-Sepharose with the anionic dye blue dextran. The resultant blue dextran-albumin-Sepharose allowed purification of anti-albumin-antibody with high yield. It is shown that the isolated antibody is pure and retains its native properties.