FIG. 7.

Acetoacetyl-CoA thiolase proceeds via a ping-pong mechanism. (A) Acetoacetyl-CoA thiolysis (reaction 2). Assays employed the indicated concentrations of CoA and either 11 (•), 23 (○), 34 (▪), or 45 μM (□) acetoacetyl-CoA. Inset: the Y intercepts were plotted versus the reciprocal of acetoacetyl-CoA concentration. (B) CoA competes with acetyl-CoA during synthesis of acetoacetyl-CoA. The reaction employed 0 (•), 30 (○), or 60 mM (□) CoA, the indicated concentrations of acetyl-CoA, and otherwise standard conditions.