Influence of Certain Cations on Activity of Acetic Thiokinase from Spinach Leaves.

The first evidence for a cofactor necessary in acetate metabolism was provided by Nachmansohn and Machado (13) who discovered a soluble enzyme system in extracts of brain tissue which catalyzed the acetylation of choline in the presence of adenosine triphosphate (ATP). Lipmann (8) and Kaplan and Lipmann (5) described an enzyme system in extracts of pigeon liver which catalyzed the ATP and coenzyme A (CoA) dependent acetylation of sulfanilamide. These investigators were the first to identify CoA as a necessary factor in acetate activation. Final proof of the constitution of active acetate was provided when Lynen and Reichert (10) isolated and identified acetyl CoA. Enzyme extracts were obtained from pig heart and rabbit heart by Beinert et al (1) and pigeon liver and yeast by Jones et al (4) which catalyzed the reversible reaction of ATP, acetate, and CoA to yield acetyl CoA, adenosine monophosphate (AMP), and inorganic pyrophosphate (PP). The overall reaction is formulated in the following equation: