The interaction of methanol dehydrogenase and its cytochrome electron acceptor

Abstract

A fluorescence method is described for direct measurement of the interaction between methanol dehydrogenase (MDH) and its electron acceptor cytochrome c(L). This has permitted a distinction to be made between factors affecting electron transfer and those affecting the initial binding or docking process. It was confirmed that the initial interaction is electrostatic, but previous conclusions with respect to the mechanism of EDTA inhibition have been modified. It is proposed that the initial 'docking' of MDH and cytochrome c(L) is by way of ionic interactions between lysyl residues on its surface and carboxylate groups on the surface of cytochrome c(L). This interaction is not inhibited by EDTA, which we suggest acts by binding to nearby lysyl residues, thus preventing movement of the 'docked' cytochrome to its optimal position for electron transfer, which probably involves interaction with the hydrophobic funnel in the surface of MDH.