The Dependence of the Photocurrent on the Concentration of Electron Mediator (Para-Benzoquinone) in Thylakoids

Abstract

The photocurrent harvested from the isolated thylakoids has been investigated as a function of concentration of electron mediator. This photocurrent measured has been verified indeed from the photosynthesis on the thylakoid membranes. The photocurrent has a linear dependence on light intensity; the photocurrent shares similar frequency dependence as that of absorption spectrum of chlorophyll; the photocurrent decreases or disappears with the application of 3-(3',4'-dichlorophenyl)-1,1-dimethylurea as an inhibitor. A new finding of a peak in the photocurrent as a function of the concentration CBQ of electron mediator para-benzoquinone (p-BQ) has been reported here. It is found that the photocurrent measured increases at small CBQ, and a maximum current is obtained at CBQ approximately equal to 1.8-2 mM and decreases with further increase in CBQ. A simplistic model has been proposed to explain the peak. The effect of bias voltage applied between the electrodes on photocurrent is studied as well.