Oxygen-Linked Hydrogen Ion Binding of Human Hemoglobin. Effects of Carbon Dioxide and 2,3-Diphosphoglycerate I. Studies on Erythrolysate

Abstract

Acid-base titrations were performed on oxygenated and deoxygenated erythrolysates at constant PCO2. The Haldane coefficient, - (δHb-bound H+)/(δHb-bound O2), was determined as a function of pH and PCO2 for various concentrations of 2,3-diphosphoglycerate (DPG). At PCO2=0 DPG causes a decrease or increase in the coefficient for pH < 7.0 or pH > 7.0, respectively. The equilibrium constants Kz (acid-base) and Kc (carbamate) of the terminal -NH2 of the β-chains of deoxy-hemoglobin were evaluated. DPG decreases both constants, especially Kz.