Influence of molecular structure on O2-binding properties and blood circulation of hemoglobin?albumin clusters

Abstract

A hemoglobin wrapped covalently by three human serum albumins, a Hb-HAS3 cluster, is an artificial O2-carrier with the potential to function as a red blood cell substitute. This paper describes the synthesis and O2-binding properties of new hemoglobin?albumin clusters(i) bearing four HSA units at the periphery(Hb-HSA4, large-size variant) and(ii) containing an intramolecularly crosslinked Hb in the center(XLHb-HSA3, high O2-affinity variant). Dynamic light scattering measurements revealed that the Hb-HSA4 diameter is greater than that of either Hb-HSA3 or XLHb-HSA3. The XLHb-HSA3 showed moderately high O2-affinity compared to the others because of the chemical linkage between the Cys-93(β) residues in Hb. Furthermore, the blood circulation behavior of 125I-labeled clusters was investigated by assay of blood retention and tissue distribution after intravenous administration into anesthetized rats. The XLHb-HSA3 was metabolized faster than Hb-HSA3 and Hb-HSA4. Results suggest that the molecular structure of the protein cluster is a factor that can influence in vivo circulation behavior.