CYCLIC VOLTAMMETRY MEASUREMENTS OF THE PHOTOELECTROGENIC REACTIONS OF THYLAKOID MEMBRANES

Abstract— In this paper, the technique of cyclic voltammetry has been used in a photoelectrochemical cell in order to follow the redox species formed in solution by the photo-induced electron transfer between the thylakoids and various acceptors and donors. The photoelectrochemical behavior of artificial electron acceptors (such as 2,5-dichlorobenzoquinone and methylviologen) and donors (such as sym -diphenylcarbazide and durohydroquinone) specific for either Photosystem I or Photosystem II has been investigated. The influence of inhibiting agents (such as 3-(3,4-dichlorophenyl)-1,1-dimethylurea and Tris) on the cell photoresponse has also been characterized, together with the capability of donors to restore the photocurrent. Evidence for H₂O₂ formation by way of a Mehler-type reaction has been provided and an electrochemical model of its coupled photochemical and electrochemical reactions in solution is reported.