Figure 10.

α-Aminoisobutryric acid is an alternative substrate for ACCO producing acetone, ammonia and CO₂. In the presence of cyanide (CN⁻) and AIB, ACCO is activated and enzyme inactivation is prevented. Without CN⁻ and AIB, ACCO is inactivated. Cyanide or AIB alone only partially prevents inactivation. The ACCO fusion protein was incubated without cyanide and AIB (open circles), 250 µM KCN plus 250 µM AIB (open squares) or 500 µM KCN plus 250 µM AIB (open triangles) for up to 2 h in the standard assay without ACC. During this time, AIB was presumed to be oxidized to products. At the times indicated, aliquots of the assay mixture were assayed in the standard assay with ACC.