Human hemoglobin conjugated to carboxylate dextran as a potential red blood cell substitute. I. Further physico-chemical characterization.

In a previous paper, we described the preparation of a conjugate by reaction of benzene tetracarboxylate-substituted dextran (dex-BTC) with oxyhemoglobin. The first biological experiments carried out on animals showed that a solution of this type of product could be regarded as an oxygen-carrying fluid. The physico-chemical properties of this conjugate have been further characterized in view of its potential application in clinical experiments. Its molecular size distribution and the fraction of intramolecularly cross-linked hemoglobin were determined by elution on various types of chromatographic columns. Moreover the conjugate's oxygen-binding properties were studied in the presence of effectors and of Cl- ions, and the results showed that the allosteric site and the Val 1 alpha residues of conjugated hemoglobin were occupied by dex-BTC. Finally, the fractions obtained after gel filtration exhibited a similar P50 whatever their molecular sizes. So far, all the results obtained are compatible with the use of the conjugate solution as a blood substitute.