INTERACTION BETWEEN PHOSPHOLIPID ASSEMBLIES AND HEMOGLOBIN (HB)

In order to prepare Hb-vesicles having a high oxygen-transporting abil ity, it is important to encapsulate concentrated Hb with a mixed lipid membrane having low lamellarity (n). The concentration of Hb in the H b-vesicles ([Hb](in)) increased with the Hb concentration used for the preparation of Hb-vesicles. Hb-vesicles with smaller lamellarity coul d be obtained y lowering the preparation temperature. The encapsulatio n of Hb was significantly influenced by the ionic strength and the sol ution pH because lipids and Hb are electrolytes. The lamellarity decre ases with increasing solution pH because of electrostatic repulsion be tween the surfaces of lipid membranes. On the other hand, [Hb](in) inc reases when the solution pH is lowered below the pI of Hb (7.0 at 25 d egrees C) due to electrostatic interaction between Hb and the surface of the membrane. This interaction decreases with the ionic strength of the Hb solution, leading to a lower [Hb](in).