Polymerization and Solubility of Recombinant Hemoglobins α₂β₂^6VAL (HB S) and α₂β₂^6LEU (HB LEU)

Abstract

In an effort to clarify the role of amino acid hydrophobicity at the β6 position in sickling we have made recombinant hemoglobin tetramers containing β6 Val (Hb S) and β6 Leu (Hb Leu). Recombinant Hb S and Hb Leu had the same electrophoretic mobility, chromatographic behavior, and absorption spectrum. The deoxy form of both tetramers polymerized in high phosphate buffer (1.8 M) and exhibited distinct delay times prior to polymerization. The kinetics of polymerization.for recombinant and native Hb S were similar, while recombinant Hb Leu polymerized more readily. The solubility of deoxy Hb Leu was less than deoxy Hb S, indicating that rapid polymerization and decreased solubility of deoxyhemoglobin is accelerated with increasing hydrophobicity at the β6 position.