The Enzyme Kinetics of NADH Dehydrogenase After the Addition of the Inhibitory Molecules, EDTA and Mg2+

Abstract

The oxidation of NADH to NAD+ is done by NADH dehydrogenase, a component of the electron transport chain in Escherichia coli. It has been demonstrated that when E. coli K12 cells were lysed by the lysozyme lysis method, NADH dehydrogenase activity was inhibited. On the contrary, when cells were lysed by French press, NADH dehydrogenase activity was not inhibited. In our investigation, some common components used in cell lysis were examined for their effect on purified NADH dehydrogenase activity. Attempts to partially purify the enzyme to eliminate contaminating factors were unsuccessful and potential causes were examined. It was found that individually, EDTA and MgCl both 2 inhibited the activity of NADH dehydrogenase. However, the pattern in the kinetics of inhibition of EDTA and MgCl were different and MgCl appeared to be a stronger 2 2 inhibitor of the enzyme at lower concentrations and limiting substrate levels.