Human Isoionic Hemoglobin: Preparation and Kinetic Properties

Abstract

Much of the data on hemoglobin-gas interactions which have accumulated in the literature is difficult to interpret because the hemoglobin preparations contained extraneous ligands and salts. In order to obtain hemoglobin which is completely free of 2, 3-DPG and other ionic substances, we have developed a method for isolating isoionic hemoglobin. These data serve as a baseline against which other data obtained with added ligands and salts can be compared. Specifically, isoionic hemoglobin had these properties: Second-order rate constant for combination with 0₂: 2.2 × 10⁷ M⁻¹S⁻¹; p₅₀ at 20^[ddot] was 0.87mm Hg at heme concentration of 10⁻⁴ M.