Selective heat precipitability or reduced human hemoglobins in alkaline urea

Solutions of reduced hemoglobins from patients with either SS, SC, or CC hemoglobinopathies precipitated when heated for two minutes at 100 degrees C at pH 9.20 in the presence of 3.64 M urea, while hemolysates of normal adult AA and newborns (FA hemoglobin) remained clear. In patients with hemoglobin C trait (AC) having 30% or more C hemoglobin, precipitation also occurred. The conditions of pH and urea concentration affording precipitation of hemoglobin S approximated those observed for hemoglobin C.