Discovery of a single molecule transistor in photosystem II

Abstract

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.

Isotropic exchange interaction between Mo and the proximal FeS center in the xanthine oxidase family member aldehyde oxidoreductase from Desulfovibrio gigas on native and polyalcohol inhibited samples: an EPR and QM/MM study

“…This means that the intraenzyme electron transfer process should be regulated by the catalytic labile ligand of molybdenum first coordination sphere. A ligand-based regulatory mechanism was also proposed for the electron transfer reaction between the two quinone moieties (Q A and Q B ) of photosystem II in bacteria, in which a bicarbonate ligand of the Fe(II) ion situated midway between Q A and Q B would regulate the electron flow [55].…”

The future tasks of electrochemistry: a personal view

“…Accordingly, the second important task of electrochemistry is to search for, and catalog, unequivocal examples of superexchange in electrochemical systems. I've already done this myself in the cases of polysulfide reduction [9] and photosystem II [10] but many more examples surely await discovery. Indeed, I suspect that superexchange is widespread in interfacial kinetics, but is currently "hiding in plain sight" due to the femtosecond timescale on which it operates.…”

Twenty years of the Journal of Solid State Electrochemistry

“…Regular readers of the journal will also be aware that we are publishing papers in the field of electroanalysis. Progress in electroanalysis and electrochemical sensors is currently certainly slower than progress in power sources and storage devices, but some spectacular developments are occurring: the development of dating procedures for metals (see the [34], voltammetry at three-phase junction [35], DOCC site concept [36], voltammetry at three-phase junction [5], corrosion current densities [37], non-Marcus model for electrostatic fluctuations in long-range electron transfer [38], electron transfer [39,40], Tafel slopes [41], convolution [42], IL double layer [43], equivalent circuit for C-based supercapacitors [44], single molecule transistor [45], steady-state voltammetry [46], capillarity and electrocapillarity of solid interfaces [47], normally rather rare in all journals, is another topic which will continue to be cultivated in our journal. We will also continue to draw the attention of our readers to the history of electrochemistry, e.g., history of platinum single crystal electrochemistry [48], double layer effects in electrode kinetics [49], electrochemical phase formation [50], nonaqueous media in electrochemistry [51,52], lithium batteries [53], free energy relationships [54], solid electrolyte fuel cells [55], glass electrode [56], electrochemical stripping techniques [57], electrode kinetics [58], osmotic theory [59], and theories of electrochemical double layer [60], ionic strength and electrode kinetics [61], Nernst equation [62], as we believe that this is a prerequisite for knowing where we have come from and where we have to go.…”