SCAN:Driving force vs electrostatic interactions - Which plays the main role in collisional electron transfer?

ITQB Scan Seminar

Title: Driving force vs electrostatic interactions - Which plays the main role in collisional electron transfer?

Speaker: Teresa catarino

From: Cell Physiology and NMR

Abstract:

Some organisms with potential applications in bioremediation and energy production rely on a great number of multihaem cytochromes in their periplasm that are involved in electron transfer to the extracellular space. The detailed characterization of these proteins is essential for the understanding of the molecular mechanisms underlying the bioenergetics of the organisms and also their application. We developed a method to characterize individual centres in multihaem proteins both kinetically and thermodynamically. The thermodynamic model relies on NMR data to distinguish the centres and on visible spectroscopy to calibrate reduction potentials and interactions. The kinetic characterization is based on Marcus Theory for Electron Transfer and assumes that driving force alone controls the rate of electron transfer, neglecting the effect of electrostatic interactions between the redox partners. The reduction kinetics of cytochrome c” from Methylophilus methylotrophus was studied as a function of ionic strength to test the relative importance of driving force and electrostatic interactions in collisional electron transfer and validate the kinetic model.