Citrate synthase

Citrate synthase (E.C. 2.3.3.1) is purified from a recombinant E. coli strain. The enzyme exists in nearly all living cells and stands as a pace-making enzyme in the first step of the Krebs Cycle. Citrate synthase is localized within eukaryotic cells in the mitochondrial matrix, but is encoded by nuclear DNA rather than mitochondrial. It is synthesized using cytoplasmic ribosomes, then transported into the mitochondrial matrix. Citrate synthase is commonly used as a quantitative enzyme marker for the presence of intact mitochondria. Citrate synthase catalyses the condensation reaction of acetyl-CoA and oxaloacetate producing citrate. Oxaloacetate will be regenerated after the completion of one round of the Krebs Cycle. Oxaloacetate is the first substrate to bind to the enzyme. This induces the enzyme to change its conformation, and creates a binding site for the acetyl-CoA. Only when this citroyl-CoA has formed will another conformational change cause thioester hydrolysis and release coenzyme A. This ensures that the energy released from the thioester bond cleavage will drive the condensation. The enzyme is provided in 3.2 M ammonium sulphate.

Activity: 186 U/ml

Temperature and pH optimum/stability: The optimum pH and temperature are 8.0 and 25 °C, respectively.