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.

Key Words:

• Acid-base equilibrium
• Bohr effect
• carbamino CO₂
• carbon dioxide
• 2,3-diphosphoglycerate
• erythrocyte
• Haldane effect
• hemoglobin
• hydrogen ion concentration
• oxygen