The Rates of Combination of the Isolated Chains of Human Hemoglobin with Oxygen

R W Noble,Q H Gibson,M Brunori,E Antonini,J Wyman

doi:10.1016/s0021-9258(17)36435-9

R W Noble, Q H Gibson + Show 3 more

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https://doi.org/10.1016/s0021-9258(17)36435-9

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Journal: The Journal of biological chemistry	Publication Date: Jul 1, 1969
Citations: 61	License type: cc-by

Affiliation: Cornell University

Abstract

Abstract The rates of combination of the isolated chains of human hemoglobin with oxygen have been measured by flash photolysis and stopped flow methods. The two experimental methods give similar results, and furthermore the data compare well with those obtained recently by the temperature jump relaxation method. The measured association rates are compared with the values predicted from the previously measured equilibrium and dissociation rate constants. A significant discrepancy is noted in the case of the β chains. In addition, the rates of replacement of oxygen by carbon monoxide as functions of the relative ligand concentrations have been measured, and the observed dependences are compared to those predicted from the equilibrium and kinetic constants for the individual liganding reactions.

Highlights

The rates of combination of the isolated chains of human hemoglobin with oxygen have been measured by flash photolysis and stopped flow methods
The measured association rates are compared with the values predicted from the previously measured equilibrium and dissociation rate constants
A significant discrepancy is noted in the case of the : chains

Summary

Methods

Human hemoglobin was prepared from fresh blood by the toluene method [3] or alternatively by merely lysing the washed red cells with 1 to 1.5 volumes of water followed by high speed (27,000 X g) centrifugation for 20 min to remove the stroma. These were prepared as previously described [2, 4] by following essentially the original procedure of Bucci and Fronticelli [5]. It is expected that the reactions of the isolated chains of hemoglobin with oxygen and carbon monoxide can be described by the following equations k'. Where K and L are the equilibrium constants for the reactions; k' and 1' are the association rate constants; and k and 1 the dissociation rate constants. Previous studies on the equilibrium and kinetics of these reactions [1, 2] have included the direct determination of all of the equilibrium and kinetic constants

Results

Discussion

Conclusion