Intracellular Concentrations of Coenzyme A and Its Derivatives from Clostridium acetobutylicum ATCC 824 and Their Roles in Enzyme Regulation

Abstract

Intracellular levels of coenzyme A (CoA) and its derivatives involved in the metabolic pathways for Clostridium acetobutylicum ATCC 824 were analyzed by using reverse-phase high-performance liquid chromatography (HPLC). During the shift from the acidogenic to the solventogenic or stationary growth phase, the concentration of butyryl-CoA increased rapidly and the concentrations of free CoA and acetyl-CoA decreased. These changes were accompanied by a rapid increase of the solvent pathway enzyme activity and a decrease of the acid pathway enzyme activity. Assays with several non-solvent-producing mutant strains were also carried out. Upon entry of the mutant strains to the stationary phase, the butyryl-CoA concentrations for these mutant strains were comparable to those for the wild type even though the mutants were deficient in solvent-producing enzymes. Levels of acetoacetyl-CoA, β-hydroxy-butyryl-CoA, and crotonyl-CoA compounds in both wild-type and mutant extracts were below HPLC detection thresholds (<21 μM).