Self-assembled light-driven photosynthetic-respiratory electron transport chain hybrid proton pump

Abstract

One of the fundamental biochemical reactions providing the foundation of life is photosynthesis occurring in plants and cyanobacteria. Photon energy is converted into stored chemical energy which flows through various metabolic processes that in the case of most aerobic organisms, terminates in the electron transport chain. In this study we demonstrate a synthetic hybrid photosynthetic-respiratory chain based on ruthenium(II)-terpyridine linked to cytochrome c and coupled with cytochrome c oxidase. Upon irradiation at an initial pH of 7.2, we observe proton pumping at a rate of ≈3.3 × 10³ H⁺ per s across the polymer bilayer generating a gradient up to ΔpH ≈ 0.2. Remarkably, cytochrome c oxidase appears to have a greater than 50% native mitochondrial orientation in the polymersome membrane. Our photoactive hybrid electron-proton chain generates a proton gradient that can store chemical energy which is a step towards the development of a model artificial protocell.