Ligand Exchange Reaction of Carbonylhemoglobin to Oxyhemoglobin in a Hemoglobin Liquid Membrane

In order to change carbonylhemoglobin (HbCO) to oxyhemoglobin (Hb0₂), the photodissociation of HbCO and 02-binding to hemoglobin were studied using Hb liquid membrane system in O2 atmosphere. The reduction rate of HbCO increased with illuminance and saturated nearly at 2.0 • 10⁵ lx. under a constant O2 pressure of 760 Torr. The reduction rate of HbCO was a 5-fold low when the partial O2 pressure was decreased from 760 to 0 Torr under the illuminance. In the static liquid membrane the exchanging rate of CO ligand in HbCO was decreased with the increment of the thickness of the liquid membrane, while the stirred liquid membrane showed a reverse result. The ligand exchange apparatus was made based on the obtained results, and the high flow rate of Hb solution enhanced the reduced amount of HbCO. Moreover, when the ligand exchange of Hb-vesicle dispersion was compared with an Hb solution, it proceeded more efficiently due to the encapsulation of concentrated Hb into a small compartment dispersed in a buffer solution.