Charge of the β-globin chain with different variants on in vitro assembly of the abnormal hemoglobin

In these in vitro experiments, equal amounts of normal and variant beta globin chains were incubated with limiting quantities of normal alpha chains. The fraction of total hemoglobin represented by the variant hemoglobin is plotted here versus the net charge of the variant beta chain. Separate experiments for 72 stable beta globin variants are each represented by a single open circle. The normal beta chain, which has a net charge of -2.5 at pH 7.2, is shown as the red circle at the 50 percent point. Under the same conditions, the normal alpha chain has a net charge of +2.4.