Magnetic protein conjugates, a process for the preparation thereof, and the use thereof

A process for the preparation of a magnetic protein conjugate of the formula I ##STR6## comprising:

• reacting magnetic particles M carrying amino groups with a maleimido-spacer, which reacts with amino groups, wherein X is selected from the group consisting of --(CH.sub.2).sub.3 --, phenylene, cyclohexane--CH.sub.2 --, and --CH.sub.2 --CH.sub.2 --CH.sub.2 --phenylene and said reaction forms an amide linkage between said maleimido-spacer and said amino groups to give a compound of the formula II ##STR7## and finally reacting said compound of the formula II with an immunoglobulin Ig having mercapto groups present in its hinge region, said mercapto groups produced by the reduction of interchain disulfide linkages, to give a compound of the formula I.