Direct Measurement of Light Induced Currents and Potentials Generated by Bacterial Reaction Centers

Abstract

Reaction centers (RC) isolated from Rhodopseudomonas sphaeroides have been incorporated into planar phospholipid bilayers separating two aqueous phases by three methods: By fusion of RC containing vesicles with preformed planar bilayers (1); through apposition of phospholipid monolayers containing RCs (2); and through bilayer formation from RC-phospholpid-alkane solutions (3). In a previous report using the last method, we demonstrated by flash activation that the bilayers contain two populations of RCs with opposite orientation (3). Light excitation elicits net electrical currents and potentials only if one of these two populations is blocked either by the absence of electron donors or by chemical oxidation.