Effect of dextran benzene polycarboxylates on the functional properties of human hemoglobin

The present study deals with the fixation of benzene polycarboxylates such as benzene hexacarboxylate (BHC) or benzene tetracarboxylate (BTC) onto dextran, with the aim of obtaining polyanionic polymers capable of decreasing the oxygen affinity of Hb by interacting with its phosphate binding site. The synthesis was carried out according to several reaction schemes. The polyanionic polymers presented the strongest effector properties, when the polyanionic molecule (BHC or BTC) were directly fixed onto the hydroxyl functions of dextran in the presence of a carbodiimide or by means of the benzene tetracarboxylic anhydride. The introduction of a spacer arm between the polymer and the polyanionic molecule led to the formation of crosslinking between chains of dextran. Among the synthesized polymers those which possess effector properties similar to those of 2,3-diphosphoglycerate (2,3-DPG) were bound onto oxyHb. The resulting covalent conjugates exhibited a low oxygen affinity and a molecular size quite fitted to a potential use as blood substitutes.