Discovery of a single molecule transistor in photosystem II

Quantum theory is used to rationalize the results of recent high-precision X-ray diffraction studies of photosystem II. It is proposed that a single molecule transistor regulates the flow of electrons through this remarkable system. At the core of the device, electrons flow through an iron(II) d-orbital by a process of superexchange, at a rate which is gated by the ambient ligand field. The transistor operates in the negative feedback mode, and its existence suggests that man-made molecular logic gates are technologically feasible. We believe this is the first recorded example of a single molecule electronic transistor in a living system.