The egress of oxygen from human HbO2 in solution and in the erythrocyte

Publisher Website
Google Scholar
Abstract
Spectrophotometric measurements, using the rapid-mixing constant-flow and stopped-flow techniques, have been made of the rate of egress of oxygen from human HbO2 in solution and in erythrocytes. By 120 dilution in a medium containing a high concentration of carbon monoxide k4, the rate constant of the reaction Hb4O8 [forward arrow] Hb4O6+O2 has been determined. At pH 7.4 and 20[degree] C, k4 in solution was 42.0 sec-1 and within the intact cell 41.4 sec-1. The respective activation energies were 19.3 and 18 kcal. The rate of dissociation of HbO2 to Hb, after mixing an erythrocyte suspension with Na2S2O4, was identical, over at least 50% of the reaction, with the change of HbO2 to HbCO above. An analysis of the data Indicates that the cell Membrane has little or no resistance to the passage of oxygen and the internal contents are effectively mixed.