The interaction of 2,3-diphosphoglycerate with various human hemoglobins

number of human hemoglobins, which had been "stripped " of organic phosphates and isolated by col-umn chromatography. In the presence of 2 X 10A M 2,3-diphosphoglycerate (2,3-DPG), the P50 of hemoglo-bins A, As, S, and C increased about twofold, signifying a substantial and equal decrease in oxygen affinity. Furthermore, hemoglobins Chesapeake and MMilwaukee-i which have intrinsically high and low oxygen affinities, respectively, also showed a twofold increase in P50 in the presence of 2 X 10 ' M 2,3-DPG. In comparison to these, hemoglobins Axc and F were less reactive with 2,3-DPG while hemoglobin Fi showed virtually no reactivity. The N-terminal amino of each P-chain of hemoglobin Aic is linked to a hexose. In hemoglobin FI the N-terminal amino of each ay-chain is acetylated. These results suggest that the N-terminal amino groups of the non-a-chains are involved in the binding of 2,3-DPG to hemoglobin