Net Charge and Oxygen Affinity of Human Hemoglobin Are Independent of Hemoglobin Concentration

I N T R O D U C T I O N Gary-Bobo and Solomon (1) have proposed that the anomalous osmotic behavior of the erythrocyte is due to a decrease of the net charge of hemoglobin which occurs when the hemoglobin concentration inside the erythrocyte is raised. Employing Donnan equilibrium studies, they subsequently (2) produced evidence to show that a hemoglobin charge dependence on hemoglobin concentration also exists in vitro. This phenomenon, which has been interpreted by GaryBobo and Solomon (1, 2) in terms of aggregation of hemoglobin molecules, is often quoted as an example of altered functional properties of hemoglobin at high concentrations (3, 4), and has been the subject of two Letters to the Editor in this Journal (5, 6). During recent studies on the diffusivity of hemoglobin, whose dependence on hemoglobin concentration increases sharply above a concentration of 30 g/dl (7), we became interested in the behavior of other functional properties o f hemoglobin when the hemoglobin concentration rises up to and above the values found inside erythrocytes. In this paper, we report J. GEN. PHYSIOL. @ The Rockefeller University Press 0022-1295/78/12/0765-0951.00 765 Volume 72 December 1978 765-773 on Jne 0, 2017 D ow nladed fom Published December 1, 1978