FIG. 6.

Effect of hydrogen ion concentration on activity. All assays were conducted in a solution containing 50 mM sodium acetate, 50 mM glycine, 50 mM Tris, 50 mM 2-(N-morpholino)ethanesulfonic acid at the indicated pH under otherwise standard conditions. (A) Reaction 1, synthesis of acetoacetyl-CoA (•), and reaction 2, thiolysis of acetoacetyl-CoA (○); (B) reaction 3, reductive deacylation of HMG-CoA to mevalonate (▪), and reaction 4, reduction of mevaldehyde to mevalonate (□); (C) reaction 5, oxidative acylation of mevaldehyde to HMG-CoA (◊), and reaction 6, oxidative acylation of mevalonate to HMG-CoA (⧫).