Synthesis of monomethoxypolyoxyethylene-bound haemoglobins

Monomethoxypolyoxyethylene (M?_w?5000) was chemically modified and activated in order to react with the amino-groups of human haemoglobin. The best active polymeric derivatives were obtained by substituting a carboxymethoxyl group for the hydroxyl function of the polymer and by converting the carboxyl function into a N-hydroxysuccinimide active ester. When such modified polyoxyethylene derivatives were allowed to react with haemoglobin, soluble conjugates were formed with relatively low molecular weights. Some of the polymer-bound haemoglobins exhibit good oxygen-binding properties relative to unbound haemoglobin and could be suitable for use as erythrocyte substitutes.