Oxygen equilibrium of hemoglobin J Cape Town
Polycythemia in carriers of hemoglobin J Cape Town or hemoglobin Chesapeake is thought to be produced by increased oxygen affinity of their blood. Both hemoglobins involve substitution of amino acid residue α FG-4. Measurements reported here, of the oxygen equilibrium of purified hemoglobin J Cape Town, permit direct comparison of the two hemoglobins. J Cape Town exhibits lower oxygen affinity, and greater heme-heme interaction, than Chesapeake; both exhibit normal Bohr effects. Substitution of one polar amino acid residue for another of opposite charge (arginine → glutamic acid) thus appears to create less disruption of the interface between α- and β-chains than substitution of a nonpolar residue (arginine → leucine).