[Kinetics of fumarate hydratase reaction catalyzed by free cells of Escherichia coli].

The kinetics of the fumarate hydratase (fumarase) reaction catalyzed by the cells of E. coli strain 85 at high concentrations of the substrate (potassium fumarate) were studied. An automatic procedure for determination of the reaction product--malonic acid--including the use of commercial malate dehydrogenase from porcine heart was developed. The fumarate activity of bacterial cells was studied at different concentrations of the substrate and at different pH values with intact and disrupted cells of E. coli 85 used as the enzyme source. The rate of the fumarase reaction in the E. coli cells was shown to depend on the diffusion and transport processes of the reagent transfer across the cell wall and the cytoplasmic membrane of bacterial cells. The pH optimum of the reaction in free E. coli cells (8-9) and the rate of malonic acid synthesis from potassium fumarate under optimal conditions, which varies within the concentration range of (6--13) x 10(-5) mkmole per mg of protein depending on the quality of cell, were determined.