BIOLOGICALLY ACTIVE PROTEIN HAVING IMPROVED RETENTIVITY IN BLOOD AND METHOD FOR PREPARING THE SAME

摘要

PROBLEM TO BE SOLVED: To provide a modified biologically active protein having a long retention time in blood. SOLUTION: The modified biologically active protein has dextran sulfate bonded on it, and it is prepared by reacting a biologically active protein with dextran sulfate under an alkaline condition. As the dextran sulfate, it is preferable to use dextran sulfate sodium sulfur 5. As the biologically active protein, a cytokine such as erythropoietin or a tumor cell obstruction factor can be used. This enables the extension of retention time of the biologically active protein in blood.