[Theoretical studies on the influence of binding constants of hemoglobin for ATP and 2,3-diphosphoglycerate on erythrocyte glycolysis].

In the red blood cell exist a binding equilibrium of ATP and 2,3-DPG with hemoglobin. For the metabolism only the free active levels of organic phosphates are relevant. The binding constants of hemoglobin increase with decreasing temperature and pH. Using a stoichometric model of glycolysis, the change of free concentrations by altered binding constants and its import on the energy metabolism of the erythrocyte was theoretically studied. The results are: 1. Total ATP-content (bound plus free ATP) does not depend on the binding properties of hemoglobin. 2. Total 2,3-DPG-content is changed by altered binding constants of hemoglobin. The direction of change depends on the ratio energy-consumption/substrate-uptake. 3. In the case of strong binding of organic phosphates to hemoglobin the experimentally measurable total ATP-content does not reflect the free ATP-concentration in the cell water. As a result of binding, free ATP may be low even if total ATP is unchanged. 4. The free concentration of 2,3-DPG always parallels the total content.