Kinetic studies of cytoplasmic and mitochondrial aconitate hydratases from rat liver

The kinetic properties of the cytoplasmic and mitochondrial aconitate hydratases of rat liver have been studied by measuring the formation of the two products from each of the three tricarboxylic acids used as substrate. The kinetic properties of the two enzymes are very similar; the similarity of the Km values for each of the three substrates is particularly remarkable. The results are discussed with particular reference to a possible role of the cytoplasmic aconitate hydratase in the process of gluconeogenesis. With both aconitate hydratases, substrate activation by citrate and D-isocitrate has been observed.