The effect of organic compounds on the crystal habit and crystallization of normal and sickle cell hemoglobin in phosphate buffer

Comparative studies were made on the effect of numerous organic compounds in promoting the crystallization of human hemoglobin in 1.9 m phosphate, pH 7.0. It was found that alicyclic or benzenoid structures are essential for promoting crystallization of hemoglobin under these conditions. Hemoglobin crystals prepared in the presence of toluene differed in habit from crystals prepared in its absence. It is suggested that steric factors determine the effectiveness of organic substances in promoting the crystallization of hemoglobin and that the heme group is the binding site involved in the complex formation.The solubility of homozygous sickle cell hemoglobin HbS was found to be less than the heterozygous hemoglobins AS and AC or normal hemoglobin HbA in the presence of organic substances promoting the crystallization of hemoglobin.