Electrophoresis of purified β-globin chain variants β16 Gly→Asp, β95 Lys→Glu, β120 Lys→Glu, β16 Gly→Asp, 120 Lys→Glu and β112 Cys→Asp and in vitro assembled tetramers. Purified β-globin chain variants β16 Gly→Asp, β95 Lys→Glu, β120 Lys→Glu, β16 Gly→Asp, 120 Lys→Glu and β112 Cys→Asp (A) and in vitro assembled tetramers (B) formed by mixing with α-globin chains isolated from human red blood cells and incubating in 10 mmol/L potassium phosphate buffer pH 7.0 at 25°C were analyzed by electrophoresis on cellulose acetate membranes at pH 8.6 using Supre-Heme buffer (Helena Lab, Beaumont, TX). (A) Lane 1, β^A chain (purified from human red blood cells); lane 2, β112 Cys→Asp chain; lane 3, β16 Gly→Asp chain; lane 4, β95 Lys→Glu chain; lane 5, β120 Lys→Glu chain; lane 6, β16 Gly→Asp, 120 Lys→Glu chain; and lane 7, β^S chain (purified from human red blood cells). (B) Lane 1, Hb A (α₂β₂ purified from human red blood cells); lane 2, in vitro assembled α₂β₂ (β112 Cys→Asp); lane 3, in vitro assembled α₂β₂ (β16 Gly→Asp); lane 4, in vitro assembled α₂β₂ (β95 Lys→Glu); lane 5, in vitro assembled α₂β₂ (β120 Lys→Glu); lane 6, in vitro assembled α₂β₂ (β16 Gly→Asp, 120 Lys→Glu); and, lane 7, Hb S (α₂β₂^S purified from human sickle red blood cells).