PURPOSE: To obtain the titled conjugated protein having improved efficiency as a carcinostatic agent, by bonding an immunoglobulin capable of being selectively linked to a specific antigen of the target cell or its fragment to neocarcinostatin through a specified bifunctional organic group.
CONSTITUTION: A thiol group is produced in an immunoglobulin which is capable of being selectively linked to a specific antigen possessed by a cell to be killed (the target cell for short) or its fragment, or the thiol group is introduced to the immunoglobulin or its fragment, while a maleimide group is introduced to neocarcinostatin, a carcinostatic agent. Both of them are reacted to give the desired conjugated protein wherein they are bonded through a bifunctional organic group shown by the formula [X1 and X2 are bifunctional organic group; m is 0, or 1; with the proviso that the immunoglobulin or its fragment is bonded in the (X1)m side, and neocarcinostatin is bonded in the X2 side]. Since the toxic part of the cell and a carrier part are bonded by a safe chemical bond, the toxicity of the cell on the target cell can be manifested selectively with improved efficiency.
KATOU YOSHINORI
SAITOU MASAHIKO
HARA TAKESHI
