Effect of organic and inorganic phosphates on the oxygen equilibrium of human erythrocytes

The effect of organic and inorganic phosphates on the functional properties of purified adult human hemoglobin has been investigated. Adenosine triphosphate, guanosine triphosphate, and 2,3-diphosphoglycerate are particularly effective in decreasing the oxygen affinity of hemoglobin and are responsible for a small change in heme-heme interaction. The di- and mononucleotides have a neglibigle effect on the log p 1 2 and n values. Hexametaphosphate causes marked changes in both the oxygen affinity and the oxygen equilibrium curve, but tripolyphosphate, tetrametaphosphate, and pyrophosphate are less effective. The oxygen affinity of hemoglobin is decreased in the presence of 2,3-diphosphoglycerate over a wide pH range. At high concentrations of phosphate buffer, diphosphoglycerate has practically no effect on the log p1 2 and n values. The results are discussed in relation to the changes in the oxyhemoglobin dissociation curve of stored blood.