Effect of Ubal on the proteolysis of human Hb α-subunits in a β-thalassemic lysate. Each reaction mixture was incubated at 37°C for 2 hours with a dialyzed hemolysate from the blood cells of a β-thalassemic donor (S.O.) and either ³H-α-globin (□, ▪) or ³H-α-chains, stabilized with CO (▵, ▴) or unexposed to CO (○, •), as a proteolysis substrate. Protein degradation values are plotted for mixtures without (unfilled symbols) or with ATP, an ATP-regenerating system, and supplementary Ub (filled symbols).