Determination by NMR analyses of acetone carboxylase reaction products with 2-butanone as the substrate. (A and B) Enzymatic reactions realized without substrates. (C, D, E, and F) Enzymatic reactions realized in the presence of 81.5 μg of pure Acx with 8 mM, 12 mM, 16 mM, and 24 mM ATP, respectively. (G) Enzymatic reaction realized with 16 mM ATP and 163 μg of pure Acx. ppm, parts per million.