| Autor: |
Ilgenfritz, Georg, Schuster, Todd M. |
| Zdroj: |
Journal of Biological Chemistry; May 1974, Vol. 249 Issue: 9 p2959-2973, 15p |
| Abstrakt: |
The kinetics of oxygen binding to human hemoglobin at pH 7, 0.1 mphosphate, 20°, 2.5 x10-5to 10-3mheme has been investigated by chemical relaxation methods in order to obtain information about the elementary steps and the mechanism of the cooperative process of ligand binding. The temperature jump relaxation method allows the oxygen-binding reaction to be followed over its entire time range. The relaxation process is characterized by two phases which are well separated in time. Both the time constants and the relative amplitudes are dependent on protein and ligand concentration. The two relaxation phases can be understood qualitatively. The fast phase corresponds at low oxygen saturation mainly to the binding of the first ligand molecule and at high saturation mainly to the binding of the last ligand molecule. At intermediate oxygen saturation the fast phase is determined predominantly by the kinetics of both the first and the last step—the intermediate reaction steps do not contribute significantly. The slow relaxation phase involves all elementary binding reactions, but is determined mainly by the kinetics of the intermediate oxygen-binding steps. |
| Databáze: |
Supplemental Index |
| Externí odkaz: |
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