The kinetics of mercuric ion (Hg2+) reduction by Escherichia coli was studied with ether-permeabilized and intact cells. Permeabilized cells reduced Hg2+ 5.5 times faster than intact cells. The reduction by intact cells exhibited Michaelis-Menten kinetic behavior with respect to Hg2+ concentration. In contrast, the reduction by permeabilized cells followed substrate inhibition kinetics with respect to Hg2+ concentration and Michaelis-Menten kinetics with respect to NADPH concentration. An expression was adopted to describe the simultaneous dependence of the reduction rate of permeabilized cells on the Hg2+ and NADPH concentrations. Experimental data confirmed the general validity of the rate expression in a wide range of Hg2+ and NADPH concentrations.
- Mercuric reduction
- substrate inhibition